Hereford Arizona Observatory found fluctuations in what type of main-sequence star in Cygnus?
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Hereford Arizona Observatory Hereford Arizona Observatory (HAO), IAU-code G95, is an astronomical observatory, owned and operated by amateur astronomer Bruce L. Gary. Gary is the author of many publications related to astronomy, including "Exoplanet Observing for Amateurs" (2008), currently available in a second edition (2009). Observational studies of unusual starlight fluctuations in KIC 8462852 and WD 1145+017 are recent interests.
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KIC 8462852 KIC 8462852 (also Tabby's Star or Boyajian's Star) is an F-type main-sequence star located in the constellation Cygnus approximately 1280 ly from Earth. Unusual light fluctuations of the star, including up to a 22% dimming in brightness, were discovered by citizen scientists as part of the Planet Hunters project, and, in September 2015, astronomers and citizen scientists associated with the project posted a preprint of an article describing the data and possible interpretations. The discovery was made from data collected by the "Kepler" space telescope, which observes changes in the brightness of distant stars to detect exoplanets.
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RZ Gruis RZ Gruis is a nova-like binary system in the constellation Grus composed of a white dwarf and an F-type main sequence star. It is generally of apparent magnitude of 12.3 with occasional dimming to 13.4. Its components are thought to orbit each other roughly every 8.5 to 10 hours (much longer than most nova-like variables, which have periods of around 3 to 4 hours). It belongs to the UX Ursae Majoris subgroup of cataclysmic variable star systems, where material from the donor star is drawn to the white dwarf where it forms an accretion disc that remains bright and outshines the two component stars. The system is around 1,434 light-years away from Earth.
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Lambda1 Phoenicis Lambda Phoenicis (λ Phe) is a class A0V (white main-sequence) star in the constellation Phoenix. Its apparent magnitude is 4.76 and it is approximately 173 light years away based on parallax.
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Kepler-36 Kepler-36 is a star in the constellation of Cygnus with two known planets. It has an anomalously large radius, meaning that it is a subgiant.
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11 Canis Minoris 11 Canis Minoris is a variable star in the constellation Canis Minor. It is a white A-type main sequence dwarf with an average apparent magnitude of +5.25 and lies approximately 312 light years from Earth.
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F-type main-sequence star An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K. This temperature range gives the F-type stars a yellow-white hue. Because a main-sequence star is referred to as a dwarf star, this class of star may also be termed a yellow-white dwarf. Famous examples include Procyon A, Gamma Virginis A and B, and KIC 8462852.
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V380 Orionis V380 Ori is a young multiple star system located near the Orion Nebula in the constellation Orion, thought to be somewhere between 1 and 3 million years old. One of the component stars appears to have launched a polar jet that helped to clear the keyhole-shaped hole in the surrounding nebula known as NGC 1999. The system is surrounded by a bow shock—the total structure over 17 light-years (5.3 parsecs) across. V380 Orionis is a quadruple star system. The two main stars (until now known collectively as V380 Orionis Aa) are a spectroscopic binary system, the stars orbiting each other over a period of 106 days. The primary is a hot white Herbig Ae/Be star of spectral type B9 that has a surface temperature of 10,500 ± 500 K, and is around 2.87 times as massive and 100 times as luminous as the Sun, and is triple its diameter. The secondary is a T Tauri star that has a surface temperature of 5,500 ± 500 K, and is around 1.6 times as massive and 0.31 times as luminous as the Sun, and is twice its diameter. The two stars are surrounded by a circumstellar disk, lying almost edge-on to observers on earth.
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31 Cygni 31 Cygni, also known as ο Cygni, Omicron Cygni, or V695 Cygni, is a star in the constellation Cygnus.
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V1057 Cygni V1057 Cygni (V1057 Cyg) is a FU Orionis-type variable star in the constellation of Cygnus. It has a spectral type of F and an apparent visual magnitude of approximately 11.660. It was the second FU Orionis-type variable discovered.
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Kepler-16 Kepler-16 is a binary star system in the constellation of Cygnus that was targeted by the Kepler spacecraft. Both stars are smaller than the Sun; the primary, Kepler-16A, is a K-type main-sequence star and the secondary, Kepler-16B, is an M-type red dwarf. They are separated by 0.22 AU, and complete an orbit around a common center of mass every 41 days.
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Psi Cygni ψ Cygni (Latinised as Psi Cygni) is a triple star system in the constellation called Cygnus. With a combined apparent visual magnitude of 4.92, it is visible to the naked eye. As of 2002, the inner pair, components Aa and Ab, had an angular separation of 0.10 arc seconds along a position angle of 77.6°. Their combined visual magnitude is 5.05. Relative to this pair, the third member of the system, magnitude 7.61 component B, had an angular separation of 2.87 arc seconds along a position angle of 175.6° as of 2010. Based upon an annual parallax shift of 11.59 mas, Psi Cygni is located around 281 light years from the Sun.
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Double periodic variable A Double Periodic Variable (DPV) is a type of binary star. As the name implies, the systems vary in brightness not only due to eclipses of one star by the other, but also on a cycle of roughly 33 times longer than the orbit. The star gaining mass from the other has a thick disk of material surrounding it, and the systems apparently lose mass cyclically into the interstellar medium over time. The cause for the secondary longer variability still is not established. The stars are rare, with 21 systems found in the Galaxy and more than 170 in the Magellanic Clouds (Abril 2016).
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G Centauri G Centauri (G Cen) is a star in the constellation Centaurus. It is a blue-white B-type main sequence dwarf with an apparent magnitude of +4.82 and is approximately 450 light years from Earth.
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Blue straggler A blue straggler is a main-sequence star in an open or globular cluster that is more luminous and bluer than stars at the main-sequence turn-off point for the cluster. Blue stragglers were first discovered by Allan Sandage in 1953 while performing photometry of the stars in the globular cluster M3. Standard theories of stellar evolution hold that the position of a star on the Hertzsprung–Russell diagram should be determined almost entirely by the initial mass of the star and its age. In a cluster, stars all formed at approximately the same time, and thus in an H–R diagram for a cluster, all stars should lie along a clearly defined curve set by the age of the cluster, with the positions of individual stars on that curve determined solely by their initial mass. With masses two to three times that of the rest of the main-sequence cluster stars, blue stragglers seem to be exceptions to this rule. The resolution of this problem is likely related to interactions between two or more stars in the dense confines of the clusters in which blue stragglers are found.
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HD 191806 HD 191806 is an 8th magnitude K-type star located approximately 226 light years away in the constellation Cygnus. In 2016, a massive gas giant planet was found in orbit around the star.
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Feige 55 Feige 55 is a hot white dwarf approximately 665 light-years away from the Sun in the constellation of Ursa Major. The star is likely a post-AGB star with relatively high luminosity for a standard white dwarf. It is also in a close binary system with orbital period of 1.4933 days.
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Kepler-6 Kepler-6 is a yellow giant situated in the constellation Cygnus. The star lies within the field of view of the Kepler Mission, which discovered it as part of a NASA-led mission to discover Earth-like planets. The star, which is slightly larger, more metal-rich, slightly cooler, and more massive than the Sun, is orbited by at least one extrasolar planet, a Jupiter-sized planet named Kepler-6b that orbits closely to its star.
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HD 92945 HD 92945 is a K-type main sequence star in the constellation of Hydra. Its apparent visual magnitude varies by 0.02 magnitudes and is approximately 7.72 at maximum brightness. A debris disk has been observed around the star by coronagraphic imaging, using the ACS and NICMOS instruments on the Hubble Space Telescope. It appears to extend 45 to 175 astronomical units from HD 92945 and is inclined at approximately 29 degrees.
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55 Cygni 55 Cygni (55 Cyg) is a blue supergiant star in the constellation Cygnus. It is thought to be a member of the Cygnus OB7 stellar association at about 2,700 light years.
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Iota Cygni The Bayer designation Iota Cygni (ι Cyg / ι Cygni) is shared by two stars, in the constellation Cygnus:
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6 Equulei 6 Equulei is an A-type main sequence star in the constellation of Equuleus with an apparent magnitude of 6.07.