Universe Guide

Alrescha (Alpha Piscium, 113 Piscium B) Star Facts

Alrescha Facts

  • Alrescha is a rotating variable star that can be located in the constellation of Pisces. The description is based on the spectral class.
  • Alrescha is a main star of the constellation outline.
  • Based on the spectral type (A2) of the star, the star's colour is blue - white .
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 150.58 light years away from us. Distance

Alrescha's Alternative Names


The Id of the star in the Yale Bright Star Catalogue is HR595. HIP9487 is the reference name for the star in the Hipparcos Star Catalogue.

Alrescha has alternative name(s) :- HD 12446 J, alf Psc.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 113 Piscium B. The Flamsteed name can be shortened to 113 Psc B.



Location of Alrescha


Radial Velocity and Proper Motion of Alrescha

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving 0.04 ± 0.57 milliarcseconds/year towards the north and 32.45 ± 1.06 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 7.50000 km/s with an error of about 1.80 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Alrescha

Alrescha Colour and Temperature

Based on the star's spectral type of A2 , Alrescha's colour and type is blue - white variable star. The star has a B-V Colour Index of 0.02 which means the star's temperature is about 9,824 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Alrescha Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 59.24 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Alrescha Radius

Alrescha estimated radius has been calculated as being 2.37 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,647,420.80.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.5604823674503926063287398954. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Alrescha Apparent and Absolute Magnitudes

Alrescha has an apparent magnitude of 3.82 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 0.67 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.50. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to Alrescha

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 23.45000 which gave the calculated distance to Alrescha as 139.09 light years away from Earth or 42.64 parsecs. If you want that in miles, it is about 817,658,003,156,108.31, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 21.66000 which put Alrescha at a distance of 150.58 light years or 46.17 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 9,523,179.75 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,424.00 Parsecs or 24,214.37 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Alrescha



DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736137,203,059.78
Speed of Sound (Mach 1)767.269131,611,536.49
Concorde (Mach 2)1,534.5465,805,682.48
New Horizons Probe33,0003,060,044.00
Speed of Light670,616,629.00150.58

Variable Type of Alrescha

The star is a rotating Alpha2 Canum Venatic variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. Alrescha brightness ranges from a magnitude of 3.835 to a magnitude of 3.823 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.7 days (variability).

Source of Information


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Additional Alrescha Facts and Figures

Visual Facts

Primary / Proper / Traditional NameAlrescha
Alternative NamesAlpha Piscium, Alf Psc, HD 12446 J, HIP 9487, HR 595, 113 Piscium B, 113 Psc B, BD+02 317, alf Psc
Spectral TypeA2
Constellation's Main StarYes
Multiple Star SystemYes
Star TypeVariable Star
GalaxyMilky Way
Absolute Magnitude 0.67 / 0.50
Visual / Apparent Magnitude3.82
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)02h 02m 02.80
Declination (Dec.)+02° 45` 49.5
Galactic Latitude-55.59962119 degrees
Galactic Longitude155.35088929 degrees
1997 Distance from Earth23.45000 Parallax (milliarcseconds)
 139.09 Light Years
 42.64 Parsecs
2007 Distance from Earth21.66000 Parallax (milliarcseconds)
 150.58 Light Years
 46.17 Parsecs
 9,523,179.75 Astronomical Units
Galacto-Centric Distance24,214.37 Light Years / 7,424.00 Parsecs
Proper Motion Dec.0.04000 ± 0.57000 milliarcseconds/year
Proper Motion RA.32.45000 ± 1.06000 milliarcseconds/year
B-V Index0.02
Radial Velocity7.50000 ± 1.80 km/s
Semi-Major Axis8120.0000000
Stellar Luminosity (Lsun)59.2400000
Associated / Clustered StarsAlpha Piscium A
Alpha Piscium B

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassRotating
Variable Star TypeAlpha2 Canum Venatic
Mean Variability Period in Days0.746
Variable Magnitude Range (Brighter - Dimmer)3.823 - 3.835

Estimated Calculated Facts

Radius (x the Sun)2.56
Effective Temperature9,824 Kelvin

Sources and Links

SIMBAD SourceLink

Multi-Star System


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
12447+02 317.0A4.3000035.000002.00000A2White

Location of Alrescha in Pisces

Alrescha Location in Pisces


Pisces Main Stars

Comments and Questions



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