Universe Guide


Alrescha, Alpha Piscium, 113 Piscium, HD12446, HIP9487, HR596

Alrescha (Alpha Piscium) is a blue rotating star that can be located in the constellation of Pisces. Alrescha is the brightest star in Pisces based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Alpha Piscium is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR596. HIP9487 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD12446.

Alrescha has alternative name(s), alf Psc.

Location of Alrescha

The location of the star in the galaxy is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For Alrescha, the location is 02h 02m 02.80 and +02d45`49.5 .

Proper Motion of Alrescha

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 miliarcseconds/year towards the north and 32.45 ± 1.06 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Alrescha

Alrescha has a spectral type of A2. This means the star is a blue star. The star is 7424.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24214.3666585600000000s. The star has a B-V Colour Index of 0.02 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,824 Kelvin.

Alrescha 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. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.56. The figure is derived at by using the formula from SDSS and 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 23.45 which gave the calculated distance to Alrescha as 139.09 light years away from Earth or 42.64 parsecs. It would take a spaceship travelling at the speed of light, 139.09 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 21.66 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.

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*.

Variable Type of Alrescha

The star is a rotating Alpha2 Canum Venaticorum 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

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Alrescha Facts

Alternative Names

Traditional/Proper NameAlrescha
Flamsteed Name113 Piscium
Flamsteed Short Name113 Psc
Short Namealf Psc
Bayer DesignationAlpha Piscium
Hipparcos Library I.D.9487
Yale Bright Star Catalogue (HR) Id596
Bonner DurchmusterungBD+02 317
Henry Draper Designation12446

Visual Facts

Star Type star
Absolute Magnitude0.67 / 0.50
Visual / Apparent Magnitude3.82
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)02h 02m 02.80
Declination (Dec.)+02d45`49.5
Galactic Latitude-55.60 degrees
Galactic Longitude155.35 degrees
1997 Distance from Earth23.45 Parallax (milliarcseconds)
 139.09 Light Years
 42.64 Parsecs
2007 Revised Distance from Earth21.66 Parallax (milliarcseconds)
 150.58 Light Years
 46.17 Parsecs
Galacto-Centric Distance24,214.37 Light Years / 7,424.00 Parsecs
Proper Motion Dec.0.04 ± 0.57 milliarcseconds/year
Proper Motion RA.32.45 ± 1.06 milliarcseconds/year
B-V Index0.02
Radial Velocity7.50 ± 1.80 km/s
Spectral TypeA2
Colour(A) blue

Variable Star Details

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

Estimated Facts

Calculated Effective Temperature9,824 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

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 (Alpha Piscium) Location in Pisces

The map was generated using Night Vision, an awesome free application by Brian Simpson.

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