title: Newark, New Jersey

text: Link Community School is a non-denominational coeducational day school that serves approximately 128 students in seventh and eighth grades. The Newark Boys Chorus School was founded in the 1960s. University Heights Charter School, which opened in 2006, taught 614 students in grades Pre-K–8 in 2014–2015.


title: Newark, New Jersey

text: University Hospital EMS (UH-EMS) operates the EMS system for the city. The department operates a fleet of six BLS units staffed with two EMTs 24/7, supplemented by four 12-hour "power" units (operated during peak demand time hours), five ALS units staffed with two paramedics (one of which is stationed at Newark International Airport and covers the airport and Port Newark-Elizabeth, and frequently responds into the City of Elizabeth), and a critical care unit staffed by a paramedic and an RN. With distinction they also staff the only hospital based heavy rescue truck in the country, known as University EMS Rescue 1. The EMS system is one of the busiest systems per unit in the nation. On average, a BLS unit may be sent to 20–25 dispatches in a 12-hour shift. They also provide the medical staffing for Northstar and Southstar, which are the two NJ State Police medevac helicopters, staffing one flight nurse and a flight medic around the clock. The EMS system in Newark handles upwards of 125,000 requests for service annually. The Ironbound Volunteer Ambulance Squad helps by handling BLS calls in the East Ward when members are on duty and has been in operation since 1969. The Vailsburg Volunteer Rescue Squad helps by handling BLS calls in the West Ward when members are on duty and has been in operation since 2019.


title: Newark, New Jersey

text: The city is protected by more than 700 full-time, paid firefighters of the Newark Fire Department (NFD). Founded in 1863, the NFD operates out of 16 firehouses throughout the city that are organized into 4 firefighting battalions (Battalions 1,3,4, and 5), with each Battalion Chief under the command of a deputy chief/tour commander. There is also a Safety Battalion Chief, Battalion 2, and a Special Operations Battalion Chief, Battalion 6, on duty 24/7. The NFD operates 16 engine companies, 8 ladder companies, 1 rescue company, an Urban Search and Rescue (USAR) Collapse Rescue Unit (Rescue 2), a USAR Collapse Rescue Shoring Unit, 2 fire boats, a scuba diving unit, a mobile medical ambulance bus, an air cascade unit, a foam unit, a quick attack response vehicle (QRV 1), a mobile command unit, 3 HazMat units, and numerous special, support, and reserve units. The NFD responds to approximately 45,000 emergency calls annually. In 2006, the NFD responded to 2,681 fire and hazardous condition calls. The department is a member of the Metro USAR Strike Team, which is composed of nine North Jersey fire departments.


title: Newark, New Jersey

text: The Newark Police Department is a city-operated law enforcement agency. As of January 2014, the force had 1,006 officers in its ranks. The Director of Public Safety is Brian A. O’Hara.


title: Newark, New Jersey

text: The Essex County Sheriff's Office, the New Jersey Transit Police Department (headquartered in Penn Plaza East) and the Port Authority of New York and New Jersey Police Department are also within their jurisdiction in the city, as are the New Jersey State Police. In April 2014, it was announced that the State Police would play a more prominent role in patrolling the streets of the city under the "TIDE-TAG" program. The Essex County College Police Department, New Jersey Institute of Technology Police Department and Rutgers University Police Department patrol their respective college campuses in the city. Conrail and Amtrak Police patrol their respective rail yards and property.


title: Newark, New Jersey

text: In 2018, the Newark Police began a de-escalation training program, which they credit for the achievement of no officer firing their weapon on duty in all of 2020.


title: Newark, New Jersey

text: In 1996, "Money" magazine ranked Newark "The Most Dangerous City in the Nation." By 2007, the city recorded a total of 99 homicides for the year, representing a significant drop from the record of 161 murders set in 1981. The number of murders in 2008 dropped to 65, a decline of 30% from the previous year and the lowest in the city since 2002 when there were also 65 murders.


title: Newark, New Jersey

text: In 2010, Newark recorded 90 homicides. March 2010 was the first calendar month since 1966 in which the city did not record a homicide. Overall, there was a 6% increase in crime numbers over the previous year, including a rise in carjackings for the third straight year, with the 337 incidents raising concerns that the city was returning to its status as the "car theft capital of the world". Along with the increase in crime, the Newark Police Department increased its recovery of illegally owned guns in 2011 to 696, up from 278 in 2010. The Federal Bureau of Investigation recorded 94 homicides in 2011 and 95 in 2012. In 2012 CNNMoney ranked Newark as the 6th most dangerous city in the United States, based on numbers by FBI Crime in the United States 2011 report. The city had 10 murders in 10 days during the period ending September 6, 2013, a statistic largely attributed to the reduction of the police force. In 2013 Newark recorded 111 homicides, the first year ending in triple digits in seven years and the highest tally since 1990, accounting for 27% of all murders statewide. In 2014, the total number of homicides in Newark was 93, while Essex County as a whole had 117 murders. "The Star-Ledger" reported that there were 105 homicides in the city in 2015. The city had 72 homicides in 2017, a statistic described as a "historic low", and a sharp drop from the 96 murders recorded in the city in 2016. The Newark Police reported 69 homicides for 2018. As of August 13, 2019, after a period of 50 consecutive days without a homicide, a total of 34 had been recorded.


title: Newark, New Jersey

text: In Newark, lead concentrations in water accumulated for several years in the 2010s as a result of inaccurate testing and poor leadership. Newark's problem came from a negligence of officials who the city relied on to ensure clean water. The decrease in the quality of the water was due to several factors that were all somewhat interconnected. Lead service pipes that carry water were installed in Newark.


title: Newark, New Jersey

text: When this was realized, the city had CDM Smith, a construction company that specializes in water systems, conduct a study to determine whether or not the water quality was safe enough to drink. The results revealed that the water was in fact safe to drink, but the results were severely skewed. This is because the city receives water from two water supplies: the Pequannock Treatment Plant and the Wanaque Treatment Plant. In some sampling rounds, only areas served by Pequannock were sampled, and in other rounds, only areas served by Wanaque were sampled, and each had different contaminant control systems in place that varied in their effectiveness. The Pequannock supply uses pH adjustments and silica for its corrosion control method, which worked for two decades before losing its effectiveness in 2016, while the Wanaque supply uses orthophosphate, a much more effective precaution.


title: Newark, New Jersey

text: In addition to this, the EPA requires that samples of drinking water be taken after no one has turned on a faucet for at least eight hours. Therefore, if high levels of lead do not show up in that initial sample, no further samples are required. This sample only represents the water closest to the faucet, that has not been stagnant in lead service lines, whereas the stagnant water in the lead piping may not be drawn until much later.


title: Newark, New Jersey

text: Top officials in Newark denied that their water system had a widespread lead problem, declaring on their website that the water was absolutely safe to drink. Even after municipal water tests revealed the severity of the problem Mayor Ras Baraka mailed a brochure to the cities residents that the water meets all federal standards. Although the city called an emergency declaration to allow them to purchase and distribute water filters for faucets but many of these were faulty. The city has received three noncompliance notices for exceeding lead levels since 2017 and continues to fight its lead problem.


title: Newark, New Jersey

text: Newark is a hub of air, road, rail, and ship traffic, making it a significant gateway into the New York metropolitan area and the mid-Atlantic United States.


title: Newark, New Jersey

text: Newark Liberty International Airport is the second-busiest airport in the New York metro area and the 15th-busiest in the United States (in terms of passenger traffic). Newark Airport was the New York City area's first commercial airport, opened in 1928 on land reclaimed by the Port Authority.


title: Newark, New Jersey

text: Port Newark, on Newark Bay, is the 15th-busiest port in the world and the largest container port on the East Coast of the United States. In 2003, the port moved over $100 billion in goods.


title: Newark, New Jersey

text: The Morris Canal, stretching to Newark from Phillipsburg on the Delaware River, was completed in 1831 and allowed coal and other industrial and agricultural products from Pennsylvania to be transported cheaply and efficiently to the New York metropolitan area. The canal's completion led to increased settlement in Newark, vastly increasing the population for years to come. After the canal was decommissioned, its right of way was converted into the Newark City Subway, now known as the Newark Light Rail. Many of the subway stations still portray the canal in its original state, in the form of mosaic works.


title: Newark, New Jersey

text: As the city became increasingly congested further means of transportation were sought, eventually leading to horse-drawn trolleys. These, in turn, were replaced by electric trolleys that traveled down the main streets of downtown Newark, including Broad Street, and up Market Street near the courthouse. The trolley cars did not last long as the personal motor vehicle quickly gained popularity and slowly made the trolley system seem like a burden.


title: Newark, New Jersey

text: , the city had a total of of roadways, of which were maintained by the municipality, by Essex County, by the New Jersey Department of Transportation and by the New Jersey Turnpike Authority.


title: Newark, New Jersey

text: Newark is served by numerous highways including the New Jersey Turnpike (Interstate 95), Interstate 280, Interstate 78, the Garden State Parkway, U.S. Route 1/9, U.S. Route 22, and Route 21. Newark is connected to the Holland Tunnel and Lower Manhattan by the Pulaski Skyway, spanning both the Passaic and Hackensack Rivers, which was first constructed in 1938 and recently underwent a $900 million renovation project.


title: Newark, New Jersey

text: Local streets in Newark conform to a quasi-grid form, with major streets radiating outward (like spokes on a wheel) from the downtown area. Some major roads in the city are named after the towns to which they lead, including South Orange Avenue, Springfield Avenue, and Bloomfield Avenue, as well as Broadway, which had been renamed from Belleville Avenue.


title: Newark, New Jersey

text: In a city extensively served by mass transit, 44.2% of Newark residents did not have a car as of the 2000 Census, ranked second in the U.S. to New York City in the proportion of households without an automobile among cities with more than 250,000 people. According to the 2016 American Community Survey, the number of households without an automobile has decreased to 39.2%. The same year, the average Newark household owned .89 cars compared to a national average of 1.8 cars per household.


title: Newark, New Jersey

text: Newark Penn Station, situated just east of downtown, is the city's major train station. It is served by the PATH's interurban Newark–World Trade Center line to Jersey City and Manhattan, three NJ Transit Rail Operations (NJT) commuter rail lines, and Amtrak intercity rail service. It was designed by McKim, Mead & White and completed in 1935. One mile north, the Newark Broad Street Station is served by two NJT commuter rail lines. The two train stations are linked by the Newark Light Rail system, which also provides services from Newark Penn Station to Newark's northern communities and into the neighboring towns of Belleville and Bloomfield. Built in the bed of the Morris Canal, the light rail cars run underground in Newark's downtown area. The city's third train station, Newark Liberty International Airport, connects the Northeast Corridor to the airport via AirTrain Newark.


title: Newark, New Jersey

text: Bus service in Newark is provided by NJ Transit, CoachUSA contract operators and DeCamp in North Newark. Newark is served by NJ Transit bus routes 1, 5, 11, 13, 21, 25, 27, 28, 29, 34, 37, 39, 40, 41, 42, 43, 59, 62, 65, 66, 67, 70, 71, 72, 73, 74, 75, 76, 78, 79, 90, 92, 93, 94, 96, 99, 107, and 108. The 107 and 108 routes run to New York City. Bus route 308 is an express bus route to Six Flags Great Adventure from Newark Penn Station while 319 is an express service to Atlantic City.


title: Newark, New Jersey

text: The "go bus 25" and "go bus 28" are bus rapid transit lines through the city to Irvington, Bloomfield and Newark Liberty International Airport.


title: Newark, New Jersey

text: According to the 2016 American Community Survey, 53.7% of working city of Newark residents commuted by driving alone, 9.3% carpooled, 27.3% used public transportation, and 6.5% walked. About 5% used all other forms of transportation, including taxicab, motorcycle, and bicycle. About 5.7% of working Newark residents worked at home.


title: Newark, New Jersey

text: Newark is home to five hospitals. University Hospital, an independent institution that is a teaching hospital of Rutgers Biomedical and Health Sciences, has been the busiest Level I trauma center in the state. Newark Beth Israel Medical Center is the largest hospital in the city and is a part of Barnabas Health, the state's largest system of hospital and health care facilities. Beth Israel is also one of the oldest hospitals in the city, dating back to 1901. This 669-bed regional facility is also home to the Children's Hospital of New Jersey. Catholic Health East operates Saint Michael's Medical Center. Columbus Hospital LTACH is a longterm acute care hospital designed to focus on patients with serious and complex medical conditions that require intense specialized treatment for an extended period of recovery time. Hospitals which have been closed in recent years include the Saint James Hospital, Mount Carmel Guild Hospital and the United Hospitals Medical Center.


title: Newark, New Jersey

text: In 2016, annual testing of the water in Newark's public schools revealed elevated lead levels; more than 30 schools shut off their water fountains and turned to bottled water. In August 2019 the crisis over lead contamination in drinking water resurfaced because of new warnings from federal environmental officials. It is believed that the contamination was caused by aging lead pipes and changes in the water supply that makes the water more corrosive, causing lead from the pipes to be spread to the water inside. In August 2019, New Jersey began supplying water bottles to Newark residents in certain designated neighborhoods. On August 26, 2019, Newark officials announced a $120 million plan to expedite replacing the city's lead service lines in under three years. The 29,000 families affected by the contaminated water were provided with filters and bottled water. After testing in September, it was found that the filters were successful in 97% of homes tested, though bottled water would still be made available to those who request it. Long term-plans include the replacement of lead service lines from the water supply to homes.


title: Newark, New Jersey

text: The Consulate-General of Ecuador in New Jersey is at 400 Market Street. The Consulate-General of Portugal in Newark is at the main floor of the Newark Legal Center at One Riverfront Plaza. The Consulate-General of Colombia is at 550 Broad Street. The Vice Consulate of Italy was at 1 Gateway Center, until it was closed in 2014 for economic reasons.


title: Newark, New Jersey

text: Pope John Paul II visited the city in 1995, at which time he elevated the city's cathedral to a basilica to become the Cathedral Basilica of the Sacred Heart. In 2011, the Dalai Lama was guest of honor at the Newark Peace Education Summit.


title: Prednisone

text: Prednisone is a glucocorticoid medication mostly used to suppress the immune system and decrease inflammation in conditions such as asthma, COPD, and rheumatologic diseases. It is also used to treat high blood calcium due to cancer and adrenal insufficiency along with other steroids. It is taken by mouth.


title: Prednisone

text: Common side effects with long-term use include cataracts, bone loss, easy bruising, muscle weakness, and thrush. Other side effects include weight gain, swelling, high blood sugar, increased risk of infection, and psychosis. It is generally considered safe in pregnancy and low doses appear to be safe when breastfeeding. After prolonged use, prednisone needs to be stopped gradually.


title: Prednisone

text: Prednisone is a prodrug and must be converted to prednisolone by the liver before it becomes active. Prednisolone then binds to glucocorticoid receptors, activating them and triggering changes in gene expression.


title: Prednisone

text: Prednisone was patented in 1954 and approved for medical use in the United States in 1955. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2020, it was the 30th most commonly prescribed medication in the United States, with more than 19million prescriptions.


title: Prednisone

text: Prednisone is used for many different autoimmune diseases and inflammatory conditions, including asthma, gout, COPD, CIDP, rheumatic disorders, allergic disorders, ulcerative colitis and Crohn's disease, granulomatosis with polyangiitis, adrenocortical insufficiency, hypercalcemia due to cancer, thyroiditis, laryngitis, severe tuberculosis, hives, eczema, lipid pneumonitis, pericarditis, multiple sclerosis, nephrotic syndrome, sarcoidosis, to relieve the effects of shingles, lupus, myasthenia gravis, poison oak exposure, Ménière's disease, autoimmune hepatitis, giant-cell arteritis, the Herxheimer reaction that is common during the treatment of syphilis, Duchenne muscular dystrophy, uveitis, and as part of a drug regimen to prevent rejection after organ transplant.


title: Prednisone

text: Prednisone has also been used in the treatment of migraine headaches and cluster headaches and for severe aphthous ulcer. Prednisone is used as an antitumor drug. It is important in the treatment of acute lymphoblastic leukemia, non-Hodgkin lymphomas, Hodgkin's lymphoma, multiple myeloma, and other hormone-sensitive tumors, in combination with other anticancer drugs.


title: Prednisone

text: Prednisone is often also prescribed as a form of treatment for Sudden Sensorineural Hearing Loss (SSNHL).


title: Prednisone

text: Prednisone can be used in the treatment of decompensated heart failure to increase renal responsiveness to diuretics, especially in heart failure patients with refractory diuretic resistance with large doses of loop diuretics. In terms of the mechanism of action for this purpose: prednisone, a glucocorticoid, can improve renal responsiveness to atrial natriuretic peptide by increasing the density of natriuretic peptide receptor type A in the renal inner medullary collecting duct, thereby inducing a potent diuresis.


title: Prednisone

text: Short-term side effects, as with all glucocorticoids, include high blood glucose levels (especially in patients with diabetes mellitus or on other medications that increase blood glucose, such as tacrolimus) and mineralocorticoid effects such as fluid retention. The mineralocorticoid effects of prednisone are minor, which is why it is not used in the management of adrenal insufficiency, unless a more potent mineralocorticoid is administered concomitantly.


title: Prednisone

text: Long-term side effects include Cushing's syndrome, steroid dementia syndrome, truncal weight gain, glaucoma and cataracts, diabetes mellitus type 2, and depression upon dose reduction or cessation. Long-term steroids can also increase the risk of osteoporosis, but research has found that few of these people were taking medications to protect bones. Prednisone also results in leukocytosis.


title: Prednisone

text: When used as treatment for sudden deafness or sudden sensorineural hearing loss, it can cause or exacerbate Tinnitus or a ringing in the ears.


title: Prednisone

text: Adrenal suppression will begin to occur if prednisone is taken for longer than seven days. Eventually, this may cause the body to temporarily lose the ability to manufacture natural corticosteroids (especially cortisol), which results in dependence on prednisone. For this reason, prednisone should not be abruptly stopped if taken for more than seven days; instead, the dosage should be gradually reduced. This weaning process may be over a few days if the course of prednisone was short, but may take weeks or months if the patient had been on long-term treatment. Abrupt withdrawal may lead to an Addisonian crisis. For those on chronic therapy, alternate-day dosing may preserve adrenal function and thereby reduce side effects.


title: Prednisone

text: Glucocorticoids act to inhibit feedback of both the hypothalamus, decreasing corticotropin-releasing hormone (CRH), and corticotrophs in the anterior pituitary gland, decreasing the amount of adrenocorticotropic hormone (ACTH). For this reason, glucocorticoid analogue drugs such as prednisone down-regulate the natural synthesis of glucocorticoids. This mechanism leads to dependence in a short time and can be dangerous if medications are withdrawn too quickly. The body must have time to begin synthesis of CRH and ACTH and for the adrenal glands to begin functioning normally again.


title: Prednisone

text: Prednisone may start to result in the suppression of the hypothalamic-pituitary-adrenal (HPA) axis if used at doses 7–10 mg or higher for several weeks. This is approximately equal to the amount of endogenous cortisol produced by the body every day. As such, the HPA axis starts to become suppressed and atrophy. If this occurs the patient should be tapered off prednisone slowly to give the adrenal gland enough time to regain its function and endogenous production of steroids. Supplemental doses, or "stress doses" may be required in those with HPA axis suppression who are experiencing a higher degree of stress (e.g., illness, surgery, trauma, etc.). Failing to do so in such situations could be life-threatening.


title: Prednisone

text: The magnitude and speed of dose reduction in corticosteroid withdrawal should be determined on a case-by-case basis, taking into consideration the underlying condition being treated, and individual patient factors such as the likelihood of relapse and the duration of corticosteroid treatment. Gradual withdrawal of systemic corticosteroids should be considered in those whose disease is unlikely to relapse and have:


title: Prednisone

text: Systemic corticosteroids may be stopped abruptly in those whose disease is unlikely to relapse and who have received treatment for 3 weeks or less and who are not included in the patient groups described above.


title: Prednisone

text: During corticosteroid withdrawal, the dose may be reduced rapidly down to physiological doses (equivalent to prednisolone 7.5 mg daily) and then reduced more slowly. Assessment of the disease may be needed during withdrawal to ensure that relapse does not occur.


title: Prednisone

text: Prednisone is a synthetic glucocorticoid used for its anti-inflammatory and immunosuppressive properties. Prednisone is a prodrug; it is metabolised in the liver by 11-β-HSD to prednisolone, the active drug. Prednisone has no substantial biological effects until converted via hepatic metabolism to prednisolone.


title: Prednisone

text: Prednisone is absorbed in the gastrointestinal tract and has a half life of 2–3 hours. it has a volume of distribution of 0.4–1 L/kg. The drug is cleared by hepatic metabolism using cytochrome P450 enzymes. Metabolites are excreted in the bile and urine.


title: Prednisone

text: "Lodotra" is the brand name of an oral formulation, which releases prednisone four hours after ingestion. It is indicated for rheumatoid arthritis with morning stiffness. Taken at 10 p.m., it releases the drug at around 2 a.m.. The plasmic peak level is reached at 4 a.m., which is considered to be the optimal time for relieving morning stiffness. The drug was approved in the European Union, in January 2009.


title: Prednisone

text: The pharmaceutical industry uses prednisone tablets for the calibration of dissolution testing equipment according to the United States Pharmacopeia (USP).


title: Prednisone

text: Prednisone is a synthetic pregnane corticosteroid and derivative of cortisone and is also known as δ-cortisone or 1,2-dehydrocortisone or as 17α,21-dihydroxypregna-1,4-diene-3,11,20-trione.


title: Prednisone

text: The first isolation and structure identifications of prednisone and prednisolone were done in 1950 by Arthur Nobile. The first commercially feasible synthesis of prednisone was carried out in 1955 in the laboratories of Schering Corporation, which later became Schering-Plough Corporation, by Arthur Nobile and coworkers. They discovered that cortisone could be microbiologically oxidized to prednisone by the bacterium "Corynebacterium simplex." The same process was used to prepare prednisolone from hydrocortisone.


title: Prednisone

text: The enhanced adrenocorticoid activity of these compounds over cortisone and hydrocortisone was demonstrated in mice.


title: Prednisone

text: Prednisone and prednisolone were introduced in 1955 by Schering and Upjohn, under the brand names Meticorten and Delta-Cortef, respectively. These prescription medicines are now available from a number of manufacturers as generic drugs.


title: Supernova

text: A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the "progenitor", either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.


title: Supernova

text: Supernovae are more energetic than novae. In Latin, "nova" means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word "supernova" was coined by Walter Baade and Fritz Zwicky in 1929.


title: Supernova

text: The last supernova to be directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not long after the also naked-eye visible SN 1572, but the remnants of more recent supernovae have been found. Observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. These supernovae would almost certainly be observable with modern astronomical telescopes. The most recent naked-eye supernova was SN 1987A, which was the explosion of a blue supergiant star in the Large Magellanic Cloud, a satellite of the Milky Way.


title: Supernova

text: Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star such as a white dwarf, or the sudden gravitational collapse of a massive star's core. In the first class of events, the object's temperature is raised enough to trigger runaway nuclear fusion, completely disrupting the star. Possible causes are an accumulation of material from a binary companion through accretion, or a stellar merger. In the massive star case, the core of a massive star may undergo sudden collapse once it is unable to produce sufficient energy from fusion to counteract the star's own gravity. While some observed supernovae are more complex than these two simplified theories, the astrophysical mechanics are established and accepted by the astronomical community.


title: Supernova

text: Supernovae can expel several solar masses of material at velocities up to several percent of the speed of light. This drives an expanding shock wave into the surrounding interstellar medium, sweeping up an expanding shell of gas and dust observed as a supernova remnant. Supernovae are a major source of elements in the interstellar medium from oxygen to rubidium. The expanding shock waves of supernovae can trigger the formation of new stars. Supernova are a major source of cosmic rays. Supernovae might produce gravitational waves, though thus far, gravitational waves have been detected only from the mergers of black holes and neutron stars.


title: Supernova

text: Compared to a star's entire history, the visual appearance of a supernova is very brief, sometimes spanning several months, so that the chances of observing one with the naked eye is roughly once in a lifetime. Only a tiny fraction of the 100 billion stars in a typical galaxy have the capacity to become a supernova, being restricted to those having high mass and rare kinds of binary stars containing white dwarfs.


title: Supernova

text: The earliest possible recorded supernova, known as HB9, could have been viewed by unknown prehistoric people of the Indian subcontinent, then recorded on a rock carving found in Burzahama region in Kashmir, dated to . Later, SN 185 was documented by Chinese astronomers in 185 AD. The brightest recorded supernova was SN 1006, which occurred in 1006 AD in the constellation of Lupus. This event was described by observers across China, Japan, Iraq, Egypt, and Europe. The widely observed supernova SN 1054 produced the Crab Nebula.


title: Supernova

text: Supernovae SN 1572 and SN 1604, the latest to be observed with the naked eye in the Milky Way galaxy, had a notable influence on the development of astronomy in Europe because they were used to argue against the Aristotelian idea that the universe beyond the Moon and planets was static and unchanging. Johannes Kepler began observing SN 1604 at its peak on 17 October 1604, and continued to make estimates of its brightness until it faded from naked eye view a year later. It was the second supernova to be observed in a generation, after SN 1572 seen by Tycho Brahe in Cassiopeia.


title: Supernova

text: There is some evidence that the youngest galactic supernova, G1.9+0.3, occurred in the late 19th century, considerably more recently than Cassiopeia A from around 1680. Neither supernova was noted at the time. In the case of G1.9+0.3, high extinction from dust along the plane of our galaxy could have dimmed the event sufficiently for it to go unnoticed. The situation for Cassiopeia A is less clear; infrared light echos have been detected showing that it was not in a region of especially high extinction.


title: Supernova

text: With the development of the astronomical telescope, observation and discovery of fainter and more distant supernovae became possible. The first such observation was of SN 1885A in the Andromeda Galaxy. A second supernova, SN 1895B, was discovered in NGC 5253 a decade later. Early work on what was originally believed to be simply a new category of novae was performed during the 1920s. These were variously called "upper-class Novae", "Hauptnovae", or "giant novae". The name "supernovae" is thought to have been coined by Walter Baade and Zwicky in lectures at Caltech during 1931. It was used, as "super-Novae", in a journal paper published by Knut Lundmark in 1933, and in a 1934 paper by Baade and Zwicky. By 1938, the hyphen had been lost and the modern name was in use.


title: Supernova

text: American astronomers Rudolph Minkowski and Fritz Zwicky developed the modern supernova classification scheme beginning in 1941. During the 1960s, astronomers found that the maximum intensities of supernovae could be used as standard candles, hence indicators of astronomical distances. Some of the most distant supernovae observed in 2003 appeared dimmer than expected. This supports the view that the expansion of the universe is accelerating. Techniques were developed for reconstructing supernovae events that have no written records of being observed. The date of the Cassiopeia A supernova event was determined from light echoes off nebulae, while the age of supernova remnant RX J0852.0-4622 was estimated from temperature measurements and the gamma ray emissions from the radioactive decay of titanium-44.


title: Supernova

text: The most luminous supernova ever recorded is ASASSN-15lh, at a distance of 3.82 gigalight-years. It was first detected in June 2015 and peaked at , which is twice the bolometric luminosity of any other known supernova. However, the nature of this supernova continues to be debated and several alternative explanations have been suggested, e.g. tidal disruption of a star by a black hole.


title: Supernova

text: Among the earliest detected since time of detonation, and for which the earliest spectra have been obtained (beginning at 6 hours after the actual explosion), is SN 2013fs, which was recorded 3 hours after the supernova event on 6 October 2013 by the Intermediate Palomar Transient Factory (iPTF). The star is located in a spiral galaxy named NGC 7610, 160 million light-years away in the constellation of Pegasus.


title: Supernova

text: The supernova SN 2016gkg was detected by amateur astronomer Victor Buso from Rosario, Argentina on 20 September 2016. It was the first time that the initial 'shock breakout' from an optical supernova had been observed. The progenitor star has been identified in Hubble Space Telescope images from before its collapse. Astronomer Alex Filippenko noted: "Observations of stars in the first moments they begin exploding provide information that cannot be directly obtained in any other way."


title: Supernova

text: Because supernovae are relatively rare events within a galaxy, occurring about three times a century in the Milky Way, obtaining a good sample of supernovae to study requires regular monitoring of many galaxies. Today, amateur and professional astronomers are finding several hundred every year, some when near maximum brightness, others on old astronomical photographs or plates. Supernovae in other galaxies cannot be predicted with any meaningful accuracy. Normally, when they are discovered, they are already in progress. To use supernovae as standard candles for measuring distance, observation of their peak luminosity is required. It is therefore important to discover them well before they reach their maximum. Amateur astronomers, who greatly outnumber professional astronomers, have played an important role in finding supernovae, typically by looking at some of the closer galaxies through an optical telescope and comparing them to earlier photographs.


title: Supernova

text: Toward the end of the 20th century, astronomers increasingly turned to computer-controlled telescopes and CCDs for hunting supernovae. While such systems are popular with amateurs, there are also professional installations such as the Katzman Automatic Imaging Telescope. The Supernova Early Warning System (SNEWS) project uses a network of neutrino detectors to give early warning of a supernova in the Milky Way galaxy. Neutrinos are particles that are produced in great quantities by a supernova, and they are not significantly absorbed by the interstellar gas and dust of the galactic disk.


title: Supernova

text: Supernova searches fall into two classes: those focused on relatively nearby events and those looking farther away. Because of the expansion of the universe, the distance to a remote object with a known emission spectrum can be estimated by measuring its Doppler shift (or redshift); on average, more-distant objects recede with greater velocity than those nearby, and so have a higher redshift. Thus the search is split between high redshift and low redshift, with the boundary falling around a redshift range of "z"=0.1–0.3—where "z" is a dimensionless measure of the spectrum's frequency shift.


title: Supernova

text: High redshift searches for supernovae usually involve the observation of supernova light curves. These are useful for standard or calibrated candles to generate Hubble diagrams and make cosmological predictions. Supernova spectroscopy, used to study the physics and environments of supernovae, is more practical at low than at high redshift. Low redshift observations also anchor the low-distance end of the Hubble curve, which is a plot of distance versus redshift for visible galaxies.


title: Supernova

text: Supernova discoveries are reported to the International Astronomical Union's Central Bureau for Astronomical Telegrams, which sends out a circular with the name it assigns to that supernova. The name is formed from the prefix "SN", followed by the year of discovery, suffixed with a one or two-letter designation. The first 26 supernovae of the year are designated with a capital letter from "A" to "Z". Afterward pairs of lower-case letters are used: "aa", "ab", and so on. Hence, for example, "SN 2003C" designates the third supernova reported in the year 2003. The last supernova of 2005, SN 2005nc, was the 367th (14 × 26 + 3 = 367). Since 2000, professional and amateur astronomers have been finding several hundred supernovae each year (572 in 2007, 261 in 2008, 390 in 2009; 231 in 2013).


title: Supernova

text: Historical supernovae are known simply by the year they occurred: SN 185, SN 1006, SN 1054, SN 1572 (called "Tycho's Nova") and SN 1604 ("Kepler's Star"). Since 1885 the additional letter notation has been used, even if there was only one supernova discovered that year (e.g. SN 1885A, SN 1907A, etc.)—this last happened with SN 1947A. "SN", for SuperNova, is a standard prefix. Until 1987, two-letter designations were rarely needed; since 1988, however, they have been needed every year. Since 2016, the increasing number of discoveries has regularly led to the additional use of three-digit designations.


title: Supernova

text: Astronomers classify supernovae according to their light curves and the absorption lines of different chemical elements that appear in their spectra. If a supernova's spectrum contains lines of hydrogen (known as the Balmer series in the visual portion of the spectrum) it is classified "Type II"; otherwise it is "Type I". In each of these two types there are subdivisions according to the presence of lines from other elements or the shape of the light curve (a graph of the supernova's apparent magnitude as a function of time).


title: Supernova

text: Type I supernovae are subdivided on the basis of their spectra, with type Ia showing a strong ionised silicon absorption line. Type I supernovae without this strong line are classified as type Ib and Ic, with type Ib showing strong neutral helium lines and type Ic lacking them. The light curves are all similar, although type Ia are generally brighter at peak luminosity, but the light curve is not important for classification of type I supernovae.


title: Supernova

text: A small number of type Ia supernovae exhibit unusual features, such as non-standard luminosity or broadened light curves, and these are typically classified by referring to the earliest example showing similar features. For example, the sub-luminous SN 2008ha is often referred to as SN 2002cx-like or class Ia-2002cx.


title: Supernova

text: A small proportion of type Ic supernovae show highly broadened and blended emission lines which are taken to indicate very high expansion velocities for the ejecta. These have been classified as type Ic-BL or Ic-bl.


title: Supernova

text: Calcium-rich supernovae are a rare type of very fast supernova with unusually strong calcium lines in their spectra. Models suggest they occur when material is accreted from a helium-rich companion rather than a hydrogen-rich star. Because of helium lines in their spectra, they can resemble type Ib supernovae, but are thought to have very different progenitors.


title: Supernova

text: The supernovae of type II can also be sub-divided based on their spectra. While most type II supernovae show very broad emission lines which indicate expansion velocities of many thousands of kilometres per second, some, such as SN 2005gl, have relatively narrow features in their spectra. These are called type IIn, where the 'n' stands for 'narrow'.


title: Supernova

text: A few supernovae, such as SN 1987K and SN 1993J, appear to change types: they show lines of hydrogen at early times, but, over a period of weeks to months, become dominated by lines of helium. The term "type IIb" is used to describe the combination of features normally associated with types II and Ib.


title: Supernova

text: Type II supernovae with normal spectra dominated by broad hydrogen lines that remain for the life of the decline are classified on the basis of their light curves. The most common type shows a distinctive "plateau" in the light curve shortly after peak brightness where the visual luminosity stays relatively constant for several months before the decline resumes. These are called type II-P referring to the plateau. Less common are type II-L supernovae that lack a distinct plateau. The "L" signifies "linear" although the light curve is not actually a straight line.


title: Supernova

text: Zwicky defined additional supernovae types based on a very few examples that did not cleanly fit the parameters for type I or type II supernovae. SN 1961i in NGC 4303 was the prototype and only member of the type III supernova class, noted for its broad light curve maximum and broad hydrogen Balmer lines that were slow to develop in the spectrum. SN 1961f in NGC 3003 was the prototype and only member of the type IV class, with a light curve similar to a type II-P supernova, with hydrogen absorption lines but weak hydrogen emission lines. The type V class was coined for SN 1961V in NGC 1058, an unusual faint supernova or supernova impostor with a slow rise to brightness, a maximum lasting many months, and an unusual emission spectrum. The similarity of SN 1961V to the Eta Carinae Great Outburst was noted. Supernovae in M101 (1909) and M83 (1923 and 1957) were also suggested as possible type IV or type V supernovae.


title: Supernova

text: These types would now all be treated as peculiar type II supernovae (IIpec), of which many more examples have been discovered, although it is still debated whether SN 1961V was a true supernova following an LBV outburst or an impostor.


title: Supernova

text: Supernova type codes, as summarised in the table above, are "taxonomic": the type number is based on the light observed from the supernova, not necessarily its cause. For example, type Ia supernovae are produced by runaway fusion ignited on degenerate white dwarf progenitors, while the spectrally similar type Ib/c are produced from massive stripped progenitor stars by core collapse.


title: Supernova

text: A white dwarf star may accumulate sufficient material from a stellar companion to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it. There are three avenues by which this detonation is theorised to happen: stable accretion of material from a companion, the collision of two white dwarfs, or accretion that causes ignition in a shell that then ignites the core. The dominant mechanism by which type Ia supernovae are produced remains unclear. Despite this uncertainty in how type Ia supernovae are produced, type Ia supernovae have very uniform properties and are useful standard candles over intergalactic distances. Some calibrations are required to compensate for the gradual change in properties or different frequencies of abnormal luminosity supernovae at high redshift, and for small variations in brightness identified by light curve shape or spectrum.


title: Supernova

text: There are several means by which a supernova of this type can form, but they share a common underlying mechanism. If a carbon-oxygen white dwarf accreted enough matter to reach the Chandrasekhar limit of about 1.44 solar masses (for a non-rotating star), it would no longer be able to support the bulk of its mass through electron degeneracy pressure and would begin to collapse. However, the current view is that this limit is not normally attained; increasing temperature and density inside the core ignite carbon fusion as the star approaches the limit (to within about 1%) before collapse is initiated. In contrast, for a core primarily composed of oxygen, neon and magnesium, the collapsing white dwarf will typically form a neutron star. In this case, only a fraction of the star's mass will be ejected during the collapse.


title: Supernova

text: Within a few seconds of the collapse process, a substantial fraction of the matter in the white dwarf undergoes nuclear fusion, releasing enough energy (1–) to unbind the star in a supernova. An outwardly expanding shock wave is generated, with matter reaching velocities on the order of 5,000–20,000 km/s, or roughly 3% of the speed of light. There is also a significant increase in luminosity, reaching an absolute magnitude of −19.3 (or 5 billion times brighter than the Sun), with little variation.


title: Supernova

text: The model for the formation of this category of supernova is a close binary star system. The larger of the two stars is the first to evolve off the main sequence, and it expands to form a red giant. The two stars now share a common envelope, causing their mutual orbit to shrink. The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion. At this point, it becomes a white dwarf star, composed primarily of carbon and oxygen. Eventually, the secondary star also evolves off the main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass. The exact details of initiation and of the heavy elements produced in the catastrophic event remain unclear.


title: Supernova

text: Type Ia supernovae produce a characteristic light curve—the graph of luminosity as a function of time—after the event. This luminosity is generated by the radioactive decay of nickel-56 through cobalt-56 to iron-56. The peak luminosity of the light curve is extremely consistent across normal type Ia supernovae, having a maximum absolute magnitude of about −19.3. This is because typical type Ia supernovae arise from a consistent type of progenitor star by gradual mass acquisition, and explode when they acquire a consistent typical mass, giving rise to very similar supernova conditions and behaviour. This allows them to be used as a secondary standard candle to measure the distance to their host galaxies.


title: Supernova

text: A second model for the formation of type Ia supernovae involves the merger of two white dwarf stars, with the combined mass momentarily exceeding the Chandrasekhar limit. This is sometimes referred to as the double-degenerate model, as both stars are degenerate white dwarfs. Due to the possible combinations of mass and chemical composition of the pair there is much variation in this type of event, and, in many cases, there may be no supernova at all, in which case they will have a broader and less luminous light curve than the more normal SN type Ia.


title: Supernova

text: Abnormally bright type Ia supernovae occur when the white dwarf already has a mass higher than the Chandrasekhar limit, possibly enhanced further by asymmetry, but the ejected material will have less than normal kinetic energy. This super-Chandrasekhar-mass scenario can occur, for example, when the extra mass is supported by differential rotation.


title: Supernova

text: There is no formal sub-classification for non-standard type Ia supernovae. It has been proposed that a group of sub-luminous supernovae that occur when helium accretes onto a white dwarf should be classified as type Iax. This type of supernova may not always completely destroy the white dwarf progenitor and could leave behind a zombie star.


title: Supernova

text: One specific type of supernova originates from exploding white dwarfs, like type Ia, but contains hydrogen lines in their spectra, possibly because the white dwarf is surrounded by an envelope of hydrogen-rich circumstellar material. These supernovae have been dubbed type Ia/IIn, type Ian, type IIa and type IIan.


title: Supernova

text: The quadruple star HD 74438, belonging to the open cluster IC 2391 the Vela constellation, has been predicted to become a non-standard type Ia supernova.


title: Supernova

text: Very massive stars can undergo core collapse when nuclear fusion becomes unable to sustain the core against its own gravity; passing this threshold is the cause of all types of supernova except type Ia. The collapse may cause violent expulsion of the outer layers of the star resulting in a supernova. However, if the release of gravitational potential energy is insufficient, the star may instead collapse into a black hole or neutron star with little radiated energy.


title: Supernova

text: Core collapse can be caused by several different mechanisms: exceeding the Chandrasekhar limit; electron capture; pair-instability; or photodisintegration.


title: Supernova

text: The table below lists the known reasons for core collapse in massive stars, the types of stars in which they occur, their associated supernova type, and the remnant produced. The metallicity is the proportion of elements other than hydrogen or helium, as compared to the Sun. The initial mass is the mass of the star prior to the supernova event, given in multiples of the Sun's mass, although the mass at the time of the supernova may be much lower.


title: Supernova

text: Type IIn supernovae are not listed in the table. They can be produced by various types of core collapse in different progenitor stars, possibly even by type Ia white dwarf ignitions, although it seems that most will be from iron core collapse in luminous supergiants or hypergiants (including LBVs). The narrow spectral lines for which they are named occur because the supernova is expanding into a small dense cloud of circumstellar material. It appears that a significant proportion of supposed type IIn supernovae are supernova impostors, massive eruptions of LBV-like stars similar to the Great Eruption of Eta Carinae. In these events, material previously ejected from the star creates the narrow absorption lines and causes a shock wave through interaction with the newly ejected material.


title: Supernova

text: When a stellar core is no longer supported against gravity, it collapses in on itself with velocities reaching 70,000 km/s (0.23"c"), resulting in a rapid increase in temperature and density. What follows next depends on the mass and structure of the collapsing core, with low-mass degenerate cores forming neutron stars, higher-mass degenerate cores mostly collapsing completely to black holes, and non-degenerate cores undergoing runaway fusion.


title: Supernova

text: The initial collapse of degenerate cores is accelerated by beta decay, photodisintegration and electron capture, which causes a burst of electron neutrinos. As the density increases, neutrino emission is cut off as they become trapped in the core. The inner core eventually reaches typically 30 km in diameter with a density comparable to that of an atomic nucleus, and neutron degeneracy pressure tries to halt the collapse. If the core mass is more than about 15 solar masses then neutron degeneracy is insufficient to stop the collapse and a black hole forms directly with no supernova.


title: Supernova

text: In lower mass cores the collapse is stopped and the newly formed neutron core has an initial temperature of about 100 billion kelvin, 6,000 times the temperature of the sun's core. At this temperature, neutrino-antineutrino pairs of all flavours are efficiently formed by thermal emission. These thermal neutrinos are several times more abundant than the electron-capture neutrinos. About 10 joules, approximately 10% of the star's rest mass, is converted into a ten-second burst of neutrinos, which is the main output of the event. The suddenly halted core collapse rebounds and produces a shock wave that stalls in the outer core within milliseconds as energy is lost through the dissociation of heavy elements. A process that is is necessary to allow the outer layers of the core to reabsorb around 10 joules (1 foe) from the neutrino pulse, producing the visible brightness, although there are other theories that could power the explosion.


title: Supernova

text: Some material from the outer envelope falls back onto the neutron star, and, for cores beyond about , there is sufficient fallback to form a black hole. This fallback will reduce the kinetic energy created and the mass of expelled radioactive material, but in some situations, it may also generate relativistic jets that result in a gamma-ray burst or an exceptionally luminous supernova.


title: Supernova

text: The collapse of a massive non-degenerate core will ignite further fusion. When the core collapse is initiated by pair instability, oxygen fusion begins and the collapse may be halted. For core masses of , the collapse halts and the star remains intact, but collapse will occur again when a larger core has formed. For cores of around , the fusion of oxygen and heavier elements is so energetic that the entire star is disrupted, causing a supernova. At the upper end of the mass range, the supernova is unusually luminous and extremely long-lived due to many solar masses of ejected Ni. For even larger core masses, the core temperature becomes high enough to allow photodisintegration and the core collapses completely into a black hole.


title: Supernova

text: Stars with initial masses less than about never develop a core large enough to collapse and they eventually lose their atmospheres to become white dwarfs. Stars with at least (possibly as much as ) evolve in a complex fashion, progressively burning heavier elements at hotter temperatures in their cores. The star becomes layered like an onion, with the burning of more easily fused elements occurring in larger shells. Although popularly described as an onion with an iron core, the least massive supernova progenitors only have oxygen-neon(-magnesium) cores. These super-AGB stars may form the majority of core collapse supernovae, although less luminous and so less commonly observed than those from more massive progenitors.


title: Supernova

text: If core collapse occurs during a supergiant phase when the star still has a hydrogen envelope, the result is a type II supernova. The rate of mass loss for luminous stars depends on the metallicity and luminosity. Extremely luminous stars at near solar metallicity will lose all their hydrogen before they reach core collapse and so will not form a supernova of type II. At low metallicity, all stars will reach core collapse with a hydrogen envelope but sufficiently massive stars collapse directly to a black hole without producing a visible supernova.


title: Supernova

text: Stars with an initial mass up to about 90 times the sun, or a little less at high metallicity, result in a type II-P supernova, which is the most commonly observed type. At moderate to high metallicity, stars near the upper end of that mass range will have lost most of their hydrogen when core collapse occurs and the result will be a type II-L supernova. At very low metallicity, stars of around will reach core collapse by pair instability while they still have a hydrogen atmosphere and an oxygen core and the result will be a supernova with type II characteristics but a very large mass of ejected Ni and high luminosity.


title: Supernova

text: These supernovae, like those of type II, are massive stars that undergo core collapse. However, the stars which become types Ib and Ic supernovae have lost most of their outer (hydrogen) envelopes due to strong stellar winds or else from interaction with a companion. These stars are known as Wolf–Rayet stars, and they occur at moderate to high metallicity where continuum driven winds cause sufficiently high mass-loss rates. Observations of type Ib/c supernova do not match the observed or expected occurrence of Wolf–Rayet stars. Alternate explanations for this type of core collapse supernova involve stars stripped of their hydrogen by binary interactions. Binary models provide a better match for the observed supernovae, with the proviso that no suitable binary helium stars have ever been observed. Since a supernova can occur whenever the mass of the star at the time of core collapse is low enough not to cause complete fallback to a black hole, any massive star may result in a supernova if it loses enough mass before core collapse occurs.


title: Supernova

text: Type Ib supernovae are the more common and result from Wolf–Rayet stars of type WC which still have helium in their atmospheres. For a narrow range of masses, stars evolve further before reaching core collapse to become WO stars with very little helium remaining, and these are the progenitors of type Ic supernovae.


title: Supernova

text: A few percent of the type Ic supernovae are associated with gamma-ray bursts (GRB), though it is also believed that any hydrogen-stripped type Ib or Ic supernova could produce a GRB, depending on the circumstances of the geometry. The mechanism for producing this type of GRB is the jets produced by the magnetic field of the rapidly spinning magnetar formed at the collapsing core of the star. The jets would also transfer energy into the expanding outer shell, producing a super-luminous supernova.


title: Supernova

text: Ultra-stripped supernovae occur when the exploding star has been stripped (almost) all the way to the metal core, via mass transfer in a close binary.


title: Supernova

text: As a result, very little material is ejected from the exploding star (c. ). In the most extreme cases, ultra-stripped supernovae can occur in naked metal cores, barely above the Chandrasekhar mass limit. SN 2005ek might be the first observational example of an ultra-stripped supernova, giving rise to a relatively dim and fast decaying light curve. The nature of ultra-stripped supernovae can be both iron core-collapse and electron capture supernovae, depending on the mass of the collapsing core. Ultra-stripped supernovae are believed to be associated with the second supernova explosion in a binary system, e.g. producing a tight double neutron star system.


title: Supernova

text: In 2022 a team of astronomers led by researchers from the Weizmann Institute of Science reported the first supernova explosion showing direct evidence for a Wolf-Rayet progenitor star. SN 2019hgp was a type Icn supernova and is also the first in which the element neon has been detected.


title: Supernova

text: In 1980, a "third type" of supernova was predicted by Ken'ichi Nomoto of the University of Tokyo, called an electron-capture supernova. It would arise when a star "in the transitional range (~8 to 10 solar masses) between white dwarf formation and iron core-collapse supernovae", and with a degenerate O+Ne+Mg core, imploded after its core ran out of nuclear fuel, causing gravity to compress the electrons in the star's core into their atomic nuclei, leading to a supernova explosion and leaving behind a neutron star. In June 2021, a paper in the journal "Nature Astronomy" reported that the 2018 supernova SN 2018zd (in the galaxy NGC 2146, about 31 million light years from Earth) appeared to be the first observation of an electron-capture supernova. The 1054 supernova explosion that created the Crab Nebula in our galaxy had been thought to be the best candidate for an electron-capture supernova, and the 2021 paper makes it more likely that this was correct.


title: Supernova

text: The core collapse of some massive stars may not result in a visible supernova. This happens if the initial core collapse cannot be reversed by the mechanism that produces an explosion, usually because the core is too massive. These events are difficult to detect, but large surveys have detected possible candidates. The red supergiant N6946-BH1 in NGC 6946 underwent a modest outburst in March 2009, before fading from view. Only a faint infrared source remains at the star's location.


title: Supernova

text: A historic puzzle concerned the source of energy that can maintain the optical supernova glow for months. The ejecta gases would dim quickly without some energy input to keep it hot. Some have considered rotational energy from the central pulsar as a source. Although the energy that initially powers each type of supernovae is delivered promptly, the light curves are dominated by subsequent radioactive heating of the rapidly expanding ejecta. The intensely radioactive nature of the ejecta gases was first calculated on sound nucleosynthesis grounds in the late 1960s, and this has since been demonstrated as correct for most supernovae. It was not until SN 1987A that direct observation of gamma-ray lines unambiguously identified the major radioactive nuclei.


title: Supernova

text: It is now known by direct observation that much of the light curve (the graph of luminosity as a function of time) after the occurrence of a type II Supernova, such as SN 1987A, is explained by those predicted radioactive decays. Although the luminous emission consists of optical photons, it is the radioactive power absorbed by the ejected gases that keeps the remnant hot enough to radiate light. The radioactive decay of Ni through its daughters Co to Fe produces gamma-ray photons, primarily with energies of and , that are absorbed and dominate the heating and thus the luminosity of the ejecta at intermediate times (several weeks) to late times (several months). Energy for the peak of the light curve of SN1987A was provided by the decay of Ni to Co (half-life 6 days) while energy for the later light curve in particular fit very closely with the 77.3-day half-life of Co decaying to Fe. Later measurements by space gamma-ray telescopes of the small fraction of the Co and Co gamma rays that escaped the SN 1987A remnant without absorption confirmed earlier predictions that those two radioactive nuclei were the power sources.


title: Supernova

text: The visual light curves of the different supernova types all depend at late times on radioactive heating, but they vary in shape and amplitude because of the underlying mechanisms, the way that visible radiation is produced, the epoch of its observation, and the transparency of the ejected material. The light curves can be significantly different at other wavelengths. For example, at ultraviolet wavelengths there is an early extremely luminous peak lasting only a few hours corresponding to the breakout of the shock launched by the initial event, but that breakout is hardly detectable optically.


title: Supernova

text: The light curves for type Ia are mostly very uniform, with a consistent maximum absolute magnitude and a relatively steep decline in luminosity. Their optical energy output is driven by radioactive decay of ejected nickel-56 (half-life 6 days), which then decays to radioactive cobalt-56 (half-life 77 days). These radioisotopes excite the surrounding material to incandescence. Studies of cosmology today rely on Ni radioactivity providing the energy for the optical brightness of supernovae of type Ia, which are the "standard candles" of cosmology but whose diagnostic and gamma rays were first detected only in 2014. The initial phases of the light curve decline steeply as the effective size of the photosphere decreases and trapped electromagnetic radiation is depleted. The light curve continues to decline in the B band while it may show a small shoulder in the visual at about 40 days, but this is only a hint of a secondary maximum that occurs in the infra-red as certain ionised heavy elements recombine to produce infra-red radiation and the ejecta become transparent to it. The visual light curve continues to decline at a rate slightly greater than the decay rate of the radioactive cobalt (which has the longer half-life and controls the later curve), because the ejected material becomes more diffuse and less able to convert the high energy radiation into visual radiation. After several months, the light curve changes its decline rate again as positron emission becomes dominant from the remaining cobalt-56, although this portion of the light curve has been little-studied.


title: Supernova

text: Type Ib and Ic light curves are basically similar to type Ia although with a lower average peak luminosity. The visual light output is again due to radioactive decay being converted into visual radiation, but there is a much lower mass of the created nickel-56. The peak luminosity varies considerably and there are even occasional type Ib/c supernovae orders of magnitude more and less luminous than the norm. The most luminous type Ic supernovae are referred to as hypernovae and tend to have broadened light curves in addition to the increased peak luminosity. The source of the extra energy is thought to be relativistic jets driven by the formation of a rotating black hole, which also produce gamma-ray bursts.


title: Supernova

text: The light curves for type II supernovae are characterised by a much slower decline than type I, on the order of 0.05 magnitudes per day, excluding the plateau phase. The visual light output is dominated by kinetic energy rather than radioactive decay for several months, due primarily to the existence of hydrogen in the ejecta from the atmosphere of the supergiant progenitor star. In the initial destruction this hydrogen becomes heated and ionised. The majority of type II supernovae show a prolonged plateau in their light curves as this hydrogen recombines, emitting visible light and becoming more transparent. This is then followed by a declining light curve driven by radioactive decay although slower than in type I supernovae, due to the efficiency of conversion into light by all the hydrogen.


title: Supernova

text: In type II-L the plateau is absent because the progenitor had relatively little hydrogen left in its atmosphere, sufficient to appear in the spectrum but insufficient to produce a noticeable plateau in the light output. In type IIb supernovae the hydrogen atmosphere of the progenitor is so depleted (thought to be due to tidal stripping by a companion star) that the light curve is closer to a type I supernova and the hydrogen even disappears from the spectrum after several weeks.


title: Supernova

text: Type IIn supernovae are characterised by additional narrow spectral lines produced in a dense shell of circumstellar material. Their light curves are generally very broad and extended, occasionally also extremely luminous and referred to as a superluminous supernova. These light curves are produced by the highly efficient conversion of kinetic energy of the ejecta into electromagnetic radiation by interaction with the dense shell of material. This only occurs when the material is sufficiently dense and compact, indicating that it has been produced by the progenitor star itself only shortly before the supernova occurs.


title: Supernova

text: Large numbers of supernovae have been catalogued and classified to provide distance candles and test models. Average characteristics vary somewhat with distance and type of host galaxy, but can broadly be specified for each supernova type.


title: Supernova

text: A long-standing puzzle surrounding type II supernovae is why the remaining compact object receives a large velocity away from the epicentre; pulsars, and thus neutron stars, are observed to have high peculiar velocities, and black holes presumably do as well, although they are far harder to observe in isolation. The initial impetus can be substantial, propelling an object of more than a solar mass at a velocity of 500 km/s or greater. This indicates an expansion asymmetry, but the mechanism by which momentum is transferred to the compact object a puzzle. Proposed explanations for this kick include convection in the collapsing star and jet production during neutron star formation.


title: Supernova

text: One possible explanation for this asymmetry is large-scale convection above the core. The convection can create variations in the local abundances of elements, resulting in uneven nuclear burning during the collapse, bounce and resulting expansion.


title: Supernova

text: Another possible explanation is that accretion of gas onto the central neutron star can create a disk that drives highly directional jets, propelling matter at a high velocity out of the star, and driving transverse shocks that completely disrupt the star. These jets might play a crucial role in the resulting supernova. (A similar model is now favored for explaining long gamma-ray bursts.)


title: Supernova

text: Initial asymmetries have also been confirmed in type Ia supernovae through observation. This result may mean that the initial luminosity of this type of supernova depends on the viewing angle. However, the expansion becomes more symmetrical with the passage of time. Early asymmetries are detectable by measuring the polarization of the emitted light.


title: Supernova

text: Although supernovae are primarily known as luminous events, the electromagnetic radiation they release is almost a minor side-effect. Particularly in the case of core collapse supernovae, the emitted electromagnetic radiation is a tiny fraction of the total energy released during the event.


title: Supernova

text: There is a fundamental difference between the balance of energy production in the different types of supernova. In type Ia white dwarf detonations, most of the energy is directed into heavy element synthesis and the kinetic energy of the ejecta. In core collapse supernovae, the vast majority of the energy is directed into neutrino emission, and while some of this apparently powers the observed destruction, 99%+ of the neutrinos escape the star in the first few minutes following the start of the collapse.


title: Supernova

text: Standard Type Ia supernovae derive their energy from a runaway nuclear fusion of a carbon-oxygen white dwarf. The details of the energetics are still not fully understood, but the result is the ejection of the entire mass of the original star at high kinetic energy. Around half a solar mass of that mass is Ni generated from silicon burning. Ni is radioactive and decays into Co by beta plus decay (with a half life of six days) and gamma rays. Co itself decays by the beta plus (positron) path with a half life of 77 days into stable Fe. These two processes are responsible for the electromagnetic radiation from type Ia supernovae. In combination with the changing transparency of the ejected material, they produce the rapidly declining light curve.


title: Supernova

text: Core collapse supernovae are on average visually fainter than type Ia supernovae, but the total energy released is far higher. In these type of supernovae, the gravitational potential energy is converted into kinetic energy that compresses and collapses the core, initially producing electron neutrinos from disintegrating nucleons, followed by all flavours of thermal neutrinos from the super-heated neutron star core. Around 1% of these neutrinos are thought to deposit sufficient energy into the outer layers of the star to drive the resulting catastrophe, but again the details cannot be reproduced exactly in current models. Kinetic energies and nickel yields are somewhat lower than type Ia supernovae, hence the lower peak visual luminosity of type II supernovae, but energy from the de-ionisation of the many solar masses of remaining hydrogen can contribute to a much slower decline in luminosity and produce the plateau phase seen in the majority of core collapse supernovae.


title: Supernova

text: In some core collapse supernovae, fallback onto a black hole drives relativistic jets which may produce a brief energetic and directional burst of gamma rays and also transfers substantial further energy into the ejected material. This is one scenario for producing high-luminosity supernovae and is thought to be the cause of type Ic hypernovae and long-duration gamma-ray bursts. If the relativistic jets are too brief and fail to penetrate the stellar envelope then a low luminosity gamma-ray burst may be produced and the supernova may be sub-luminous.


title: Supernova

text: When a supernova occurs inside a small dense cloud of circumstellar material, it will produce a shock wave that can efficiently convert a high fraction of the kinetic energy into electromagnetic radiation. Even though the initial energy was entirely normal the resulting supernova will have high luminosity and extended duration since it does not rely on exponential radioactive decay. This type of event may cause type IIn hypernovae.


title: Supernova

text: Although pair-instability supernovae are core collapse supernovae with spectra and light curves similar to type II-P, the nature after core collapse is more like that of a giant type Ia with runaway fusion of carbon, oxygen, and silicon. The total energy released by the highest-mass events is comparable to other core collapse supernovae but neutrino production is thought to be very low, hence the kinetic and electromagnetic energy released is very high. The cores of these stars are much larger than any white dwarf and the amount of radioactive nickel and other heavy elements ejected from their cores can be orders of magnitude higher, with consequently high visual luminosity.


title: Supernova

text: The supernova classification type is closely tied to the type of star at the time of the collapse. The occurrence of each type of supernova depends dramatically on the metallicity, and hence the age of the host galaxy.


title: Supernova

text: Type Ia supernovae are produced from white dwarf stars in binary star systems and occur in all galaxy types. Core collapse supernovae are only found in galaxies undergoing current or very recent star formation, since they result from short-lived massive stars. They are most commonly found in type Sc spirals, but also in the arms of other spiral galaxies and in irregular galaxies, especially starburst galaxies.


title: Supernova

text: Type Ib/c and II-L, and possibly most type IIn, supernovae are only thought to be produced from stars having near-solar metallicity levels that result in high mass loss from massive stars, hence they are less common in older, more-distant galaxies. The table shows the progenitor for the main types of core collapse supernova, and the approximate proportions that have been observed in the local neighbourhood.


title: Supernova

text: There are a number of difficulties reconciling modelled and observed stellar evolution leading up to core collapse supernovae. Red supergiants are the progenitors for the vast majority of core collapse supernovae, and these have been observed but only at relatively low masses and luminosities, below about and , respectively. Most progenitors of type II supernovae are not detected and must be considerably fainter, and presumably less massive. This discrepancy has been referred to as the red supergiant problem. It was first described in 2009 by Stephen Smartt, who also coined the term. After performing a volume-limited search for supernovae, Smartt et al. found the lower and upper mass limits for type II-P supernovae to form to be and respectively. The former is consistent with the expected upper mass limits for white dwarf progenitors to form, but the latter is not consistent with massive star populations in the Local Group. The upper limit for red supergiants that produce a visible supernova explosion has been calculated at .


title: Supernova

text: It is now proposed that higher mass red supergiants do not explode as supernovae, but instead evolve back towards hotter temperatures. Several progenitors of type IIb supernovae have been confirmed, and these were K and G supergiants, plus one A supergiant. Yellow hypergiants or LBVs are proposed progenitors for type IIb supernovae, and almost all type IIb supernovae near enough to observe have shown such progenitors.


title: Supernova

text: Until just a few decades ago, hot supergiants were not considered likely to explode, but observations have shown otherwise. Blue supergiants form an unexpectedly high proportion of confirmed supernova progenitors, partly due to their high luminosity and easy detection, while not a single Wolf–Rayet progenitor has yet been clearly identified. Models have had difficulty showing how blue supergiants lose enough mass to reach supernova without progressing to a different evolutionary stage. One study has shown a possible route for low-luminosity post-red supergiant luminous blue variables to collapse, most likely as a type IIn supernova. Several examples of hot luminous progenitors of type IIn supernovae have been detected: SN 2005gy and SN 2010jl were both apparently massive luminous stars, but are very distant; and SN 2009ip had a highly luminous progenitor likely to have been an LBV, but is a peculiar supernova whose exact nature is disputed.


title: Supernova

text: The progenitors of type Ib/c supernovae are not observed at all, and constraints on their possible luminosity are often lower than those of known WC stars. WO stars are extremely rare and visually relatively faint, so it is difficult to say whether such progenitors are missing or just yet to be observed. Very luminous progenitors have not been securely identified, despite numerous supernovae being observed near enough that such progenitors would have been clearly imaged. Population modelling shows that the observed type Ib/c supernovae could be reproduced by a mixture of single massive stars and stripped-envelope stars from interacting binary systems. The continued lack of unambiguous detection of progenitors for normal type Ib and Ic supernovae may be due to most massive stars collapsing directly to a black hole without a supernova outburst. Most of these supernovae are then produced from lower-mass low-luminosity helium stars in binary systems. A small number would be from rapidly-rotating massive stars, likely corresponding to the highly-energetic type Ic-BL events that are associated with long-duration gamma-ray bursts.


title: Supernova

text: Supernovae events generate heavier elements that are scattered throughout the surrounding interstellar medium. The expanding shock wave from a supernovae can trigger star formation. Galactic cosmic rays are generated by supernova explosions.


title: Supernova

text: Supernovae are a major source of elements in the interstellar medium from oxygen through to rubidium, though the theoretical abundances of the elements produced or seen in the spectra varies significantly depending on the various supernova types. Type Ia supernovae produce mainly silicon and iron-peak elements, metals such as nickel and iron. Core collapse supernovae eject much smaller quantities of the iron-peak elements than type Ia supernovae, but larger masses of light alpha elements such as oxygen and neon, and elements heavier than zinc. The latter is especially true with electron capture supernovae. The bulk of the material ejected by type II supernovae is hydrogen and helium. The heavy elements are produced by: nuclear fusion for nuclei up to S; silicon photodisintegration rearrangement and quasiequilibrium during silicon burning for nuclei between Ar and Ni; and rapid capture of neutrons (r-process) during the supernova's collapse for elements heavier than iron. The r-process produces highly unstable nuclei that are rich in neutrons and that rapidly beta decay into more stable forms. In supernovae, r-process reactions are responsible for about half of all the isotopes of elements beyond iron, although neutron star mergers may be the main astrophysical source for many of these elements.


title: Supernova

text: In the modern universe, old asymptotic giant branch (AGB) stars are the dominant source of dust from s-process elements, oxides, and carbon. However, in the early universe, before AGB stars formed, supernovae may have been the main source of dust.


title: Supernova

text: Remnants of many supernovae consist of a compact object and a rapidly expanding shock wave of material. This cloud of material sweeps up surrounding interstellar medium during a free expansion phase, which can last for up to two centuries. The wave then gradually undergoes a period of adiabatic expansion, and will slowly cool and mix with the surrounding interstellar medium over a period of about 10,000 years.


title: Supernova

text: The Big Bang produced hydrogen, helium, and traces of lithium, while all heavier elements are synthesised in stars and supernovae. Supernovae tend to enrich the surrounding interstellar medium with elements other than hydrogen and helium, which usually astronomers refer to as "metals".


title: Supernova

text: These injected elements ultimately enrich the molecular clouds that are the sites of star formation. Thus, each stellar generation has a slightly different composition, going from an almost pure mixture of hydrogen and helium to a more metal-rich composition. Supernovae are the dominant mechanism for distributing these heavier elements, which are formed in a star during its period of nuclear fusion. The different abundances of elements in the material that forms a star have important influences on the star's life, and may decisively influence the possibility of having planets orbiting it.


title: Supernova

text: The kinetic energy of an expanding supernova remnant can trigger star formation by compressing nearby, dense molecular clouds in space. The increase in turbulent pressure can also prevent star formation if the cloud is unable to lose the excess energy.


title: Supernova

text: Evidence from daughter products of short-lived radioactive isotopes shows that a nearby supernova helped determine the composition of the Solar System 4.5 billion years ago, and may even have triggered the formation of this system.


title: Supernova

text: On 1 June 2020, astronomers reported narrowing down the source of Fast Radio Bursts (FRBs), which may now plausibly include "compact-object mergers and magnetars arising from normal core collapse supernovae".


title: Supernova

text: Supernova remnants are thought to accelerate a large fraction of galactic primary cosmic rays, but direct evidence for cosmic ray production has only been found in a small number of remnants. Gamma rays from pion-decay have been detected from the supernova remnants IC 443 and W44. These are produced when accelerated protons from the SNR impact on interstellar material.


title: Supernova

text: Supernovae are potentially strong galactic sources of gravitational waves, but none have so far been detected. The only gravitational wave events so far detected are from mergers of black holes and neutron stars, probable remnants of supernovae.


title: Supernova

text: A near-Earth supernova is a supernova close enough to the Earth to have noticeable effects on its biosphere. Depending upon the type and energy of the supernova, it could be as far as 3000 light-years away.


title: Supernova

text: In 1996 it was theorised that traces of past supernovae might be detectable on Earth in the form of metal isotope signatures in rock strata. Iron-60 enrichment was later reported in deep-sea rock of the Pacific Ocean. In 2009, elevated levels of nitrate ions were found in Antarctic ice, which coincided with the 1006 and 1054 supernovae. Gamma rays from these supernovae could have boosted atmospheric levels of nitrogen oxides, which became trapped in the ice.


title: Supernova

text: Type Ia supernovae are thought to be potentially the most dangerous if they occur close enough to the Earth. Because these supernovae arise from dim, common white dwarf stars in binary systems, it is likely that a supernova that can affect the Earth will occur unpredictably and in a star system that is not well studied. The closest known candidate is IK Pegasi, about 150 light-years away. According to a 2003 estimate, a type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half of the Earth's ozone layer, and there are no such candidates closer than about 500 light-years.


title: Supernova

text: The next supernova in the Milky Way will likely be detectable even if it occurs on the far side of the galaxy. It is likely to be produced by the collapse of an unremarkable red supergiant and it is very probable that it will already have been catalogued in infrared surveys such as 2MASS. There is a smaller chance that the next core collapse supernova will be produced by a different type of massive star such as a yellow hypergiant, luminous blue variable, or Wolf–Rayet. The chances of the next supernova being a type Ia produced by a white dwarf are calculated to be about a third of those for a core collapse supernova. Again it should be observable wherever it occurs, but it is less likely that the progenitor will ever have been observed. It isn't even known exactly what a type Ia progenitor system looks like, and it is difficult to detect them beyond a few parsecs. The total supernova rate in our galaxy is estimated to be between 2 and 12 per century, although we haven't actually observed one for several centuries.


title: Supernova

text: Statistically, the next supernova is likely to be produced from an otherwise unremarkable red supergiant, but it is difficult to identify which of those supergiants are in the final stages of heavy element fusion in their cores and which have millions of years left. The most-massive red supergiants shed their atmospheres and evolve to Wolf–Rayet stars before their cores collapse. All Wolf–Rayet stars end their lives from the Wolf–Rayet phase within a million years or so, but again it is difficult to identify those that are closest to core collapse. One class that is expected to have no more than a few thousand years before exploding are the WO Wolf–Rayet stars, which are known to have exhausted their core helium. Only eight of them are known, and only four of those are in the Milky Way.


title: Supernova

text: A number of close or well known stars have been identified as possible core collapse supernova candidates: the red supergiants Antares and Betelgeuse; the yellow hypergiant Rho Cassiopeiae; the luminous blue variable Eta Carinae that has already produced a supernova impostor; and the brightest component, a Wolf–Rayet star, in the Regor or Gamma Velorum system. Others have gained notoriety as possible, although not very likely, progenitors for a gamma-ray burst; for example WR 104.


title: Supernova

text: Identification of candidates for a type Ia supernova is much more speculative. Any binary with an accreting white dwarf might produce a supernova although the exact mechanism and timescale is still debated. These systems are faint and difficult to identify, but the novae and recurrent novae are such systems that conveniently advertise themselves. One example is U Scorpii. The nearest known Type Ia supernova candidate is IK Pegasi (HR 8210), located at a distance of 150 light-years, but observations suggest it will be several million years before the white dwarf can accrete the critical mass required to become a type Ia supernova.


title: Thalidomide

text: Thalidomide, sold under the brand names Contergan and Thalomid among others, is a medication used to treat a number of cancers (including multiple myeloma), graft-versus-host disease, and a number of skin conditions including complications of leprosy. While it has been used in a number of HIV-associated conditions, such use is associated with increased levels of the virus. It is taken by mouth.


title: Thalidomide

text: Common side effects include sleepiness, rash, and dizziness. Severe side effects include tumor lysis syndrome, blood clots, and peripheral neuropathy. Use in pregnancy may harm the fetus, including resulting in malformation of the limbs. In males who are taking the medication, contraception is essential if a partner could become pregnant. It is an immunomodulatory medication and works by a number of mechanisms, including stimulating T cells and decreasing TNF-α production.


title: Thalidomide

text: Thalidomide was first marketed in 1957 in West Germany, where it was available over the counter. When first released, thalidomide was promoted for anxiety, trouble sleeping, "tension", and morning sickness. While it was initially thought to be safe in pregnancy, concerns regarding birth defects arose until the medication was removed from the market in Europe in 1961. The total number of infants affected by use during pregnancy is estimated at 10,000, of whom about 40% died around the time of birth. Those who survived had limb, eye, urinary tract, and heart problems. Its initial entry into the US market was prevented by Frances Kelsey, a reviewer at the FDA. The birth defects caused by thalidomide led to the development of greater drug regulation and monitoring in many countries.


title: Thalidomide

text: It was approved in the United States in 1998 for use as a treatment for cancer. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication.


title: Thalidomide

text: Thalidomide is used as a first-line treatment in multiple myeloma in combination with dexamethasone or with melphalan and prednisone to treat acute episodes of erythema nodosum leprosum and for maintenance therapy.


title: Thalidomide

text: The bacterium that causes tuberculosis (TB) is related to leprosy. Thalidomide may be helpful in some cases where standard TB drugs and corticosteroids are not sufficient to resolve severe inflammation in the brain.


title: Thalidomide

text: It is used as a second-line treatment to manage graft versus host disease and aphthous stomatitis in children and has been prescribed for other conditions in children, including actinic prurigo and epidermolysis bullosa; the evidence for these uses is weak. It is recommended only as a third line treatment in graft-versus-host-disease in adults because of lack of efficacy and side effects observed in clinical trials.


title: Thalidomide

text: Thalidomide should not be used by men or women who are trying to father or conceive a child, or who cannot or will not follow the risk management program to prevent pregnancies, or by women who are breastfeeding or pregnant. The prescribing doctor is required to ensure that contraception is being used, and regular pregnancy tests are taken. Those allergic to thalidomide should not take it. It should be used with caution in people with chronic infections like HIV or hepatitis B.


title: Thalidomide

text: Thalidomide causes birth defects. The U.S. Food and Drug Administration (FDA) and other regulatory agencies have approved marketing of the drug only with an auditable risk evaluation and mitigation strategy that ensures that people using the drug are aware of the risks and avoid pregnancy; this applies to both men and women, as the drug can be transmitted in semen.


title: Thalidomide

text: There is a high risk that thalidomide can cause excessive blood clots. There is also a high risk that thalidomide can interfere with formation of various kinds of new blood cells, creating a risk of infection via neutropenia, leukopenia, and lymphopenia, and risks that blood will not clot via thrombocytopenia. There is also a risk of anemia via lack of red blood cells. The drug can also damage nerves, causing potentially irreversible peripheral neuropathy.


title: Thalidomide

text: Thalidomide has several adverse cardiovascular effects, including risk of heart attacks, pulmonary hypertension, and changes in heart rhythm, such as syncope, bradycardia, and atrioventricular block.


title: Thalidomide

text: Thalidomide can cause liver damage and severe skin reactions like Stevens–Johnson syndrome. It tends to make people sleepy, which creates risk when driving and operating other machinery. As it kills cancer cells, it can cause tumor lysis syndrome. Thalidomide can prevent menstruation.


title: Thalidomide

text: In addition, very common (reported in more than 10% of people) adverse effects include tremor, dizziness, tingling, numbness, constipation, and peripheral edema.


title: Thalidomide

text: Common adverse effects (reported by 1–10% of people) include confusion, depressed mood, reduced coordination, heart failure, difficulty breathing, interstitial lung disease, lung inflammation, vomiting, dry mouth, rashes, dry skin, fever, weakness, and a sense of unwellness.


title: Thalidomide

text: There are no expected pharmacokinetic interactions between thalidomide and other medicines due to its neutral effects on P-glycoprotein and the cytochrome P450 family. It may interact with sedatives due to its sedative action and bradycardic agents, like beta-blockers, due to its bradycardia-inducing effects. The risk of peripheral neuropathy may be increased by concomitant treatment with other agents known to cause peripheral neuropathy. The risk of venous thromboembolisms with thalidomide seems to be increased when patients are treated with oral contraceptives or other cytotoxic agents (including doxorubicin and melphalan) concurrently. Thalidomide may interfere with various contraceptives, and hence it is advised that women of reproductive age use at least two different means of contraception to ensure that no child will be conceived while they are taking thalidomide.


title: Thalidomide

text: As of 2013, eighteen cases of overdoses had been reported with doses of up to 14.4 grams, none of them fatal. No specific antidote for overdose exists and treatment is purely supportive.


title: Thalidomide

text: The precise mechanism of action for thalidomide is not known, although efforts to identify thalidomide's teratogenic action generated 2,000 research papers and the proposal of 15 or 16 plausible mechanisms by 2000. , the main theories were inhibition of the process of angiogenesis, its inhibition of cereblon, a ubiquitin ligase, and its ability to generate reactive oxygen species which in turn kills cells. In 2018, results were first published which suggested that thalidomide's teratogenic effects are mediated through degradation of the transcription factor, SALL4, an as yet unverified finding.


title: Thalidomide

text: Thalidomide also binds to and acts as an antagonist of the androgen receptor (AR) and hence is a nonsteroidal antiandrogen (NSAA) of some capacity. In accordance, it can produce gynecomastia and sexual dysfunction as side effects in men.


title: Thalidomide

text: Thalidomide is provided as a racemic mixture of two enantiomers; while there are reports that only one of the enantiomers may cause birth defects, the body converts each enantiomer into the other through mechanisms that are not well understood. The (R)-enantiomer has the desired sedative effect while the (S)-enantiomer harbors embryo-toxic and teratogenic effect. The hypothesis that the tragedy could be avoided in this case by using a single enantiomer is misleading and pointless, because it was later demonstrated that the “safe” "R"-thalidomide undergoes an "in vivo" chiral inversion to the “teratogenic” "S"-thalidomide.  Under biological conditions, the enantiomers interconvert ["bidirectional chiral inversion" - (R)- to (S)- and vice versa].


title: Thalidomide

text: Thalidomide is racemic; while "S"-thalidomide is the bioactive form of the molecule, the individual enantiomers can racemize to each other due to the acidic hydrogen at the chiral centre, which is the carbon of the glutarimide ring bonded to the phthalimide substituent. The racemization process can occur "in vivo". The process of conversion of one enantiomer to its mirror-image version with no other change in the molecule is called chiral inversion.


title: Thalidomide

text: Celgene Corporation originally synthesized thalidomide using a three-step sequence starting with -glutamic acid treatment, but this has since been reformed by the use of -glutamine. As shown in the image below, "N"-carbethoxyphthalimide (1) can react with -glutamine to yield "N"-phthaloyl--glutamine (2). Cyclization of "N"-phthaloyl--glutamine occurs using carbonyldiimidazole, which then yields thalidomide (3). Celgene Corporation's original method resulted in a 31% yield of "S"-thalidomide, whereas the two-step synthesis yields 85–93% product that is 99% pure.


title: Thalidomide

text: In 1952, thalidomide was synthesised by Chemical Industry Basel (CIBA), but was found "to have no effect on animals and was discarded" on that basis. In 1957, it was acquired by Chemie Grünenthal in Germany. The German company had been established as a soap maker after World War II ended, to address the urgent market need for antibiotics. Heinrich Mückter was appointed to head the discovery program based on his experience working with the German army's antiviral research. While preparing reagents for the work, Mueckter's assistant Wilhelm Kunz isolated a by-product that was recognized by pharmacologist Herbert Keller as an analog of glutethimide, a sedative. The medicinal chemistry work turned to improving the lead compound into a suitable drug: the result was thalidomide. The toxicity was examined in several animals, and the drug was introduced in 1956 as a sedative, but it was never tested on pregnant women.


title: Thalidomide

text: Researchers at Chemie Grünenthal found that thalidomide was a particularly effective antiemetic that had an inhibitory effect on morning sickness. On 1 October 1957, the company launched thalidomide and began marketing it under the trade name Contergan. It was proclaimed a "wonder drug" for insomnia, coughs, colds and headaches.