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Chi2 Hydrae, HD96314, HIP54255, HR4317

Chi2 Hydrae is a blue eclipsing binary system main sequence dwarf star that can be located in the constellation of Hydra. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Chi2 Hydrae's Alternative Names

Chi2 Hydrae (Chi02 Hya) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR4317. HIP54255 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD96314.

Chi2 Hydrae has alternative name(s) :- , chi02 Hya.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 265 G. Hydrae. There are no stars with a Gould designation in Ursa Major for example.

More details on star alternative names can be found at Star Names .

Location of Chi2 Hydrae

The location of the star in the night sky 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 Chi2 Hydrae, the location is 11h 05m 57.55 and -27° 17` 16.1 .

Proper Motion of Chi2 Hydrae

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 -17.04 ± 0.19 miliarcseconds/year towards the north and 34.76 ± 0.27 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 30.60000 km/s with an error of about 0.90 km/s .

Chi2 Hydrae 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 301.54 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Chi2 Hydrae

Chi2 Hydrae has a spectral type of B8V. This means the star is a blue main sequence dwarf star. The star is 7,384.00 Parsecs from the Galactic Centre or terms of Light Years is 24,083.90 s. The star has a B-V Colour Index of -0.06 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 10,611 Kelvin.

Chi2 Hydrae Radius has been calculated as being 4.94 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,434,690.20.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 4.26. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Chi2 Hydrae Apparent and Absolute Magnitudes

Chi2 Hydrae has an apparent magnitude of 5.69 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 -1.26 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.94. 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 Chi2 Hydrae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.08 which gave the calculated distance to Chi2 Hydrae as 799.42 light years away from Earth or 245.10 parsecs. It would take a spaceship travelling at the speed of light, 799.42 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 4.71 which put Chi2 Hydrae at a distance of 692.49 light years or 212.31 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 7,384.00 Parsecs or 24,083.90 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 Chi2 Hydrae

The star is a eclipsing binary system Beta Lyrae (Sheliak) 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. Chi2 Hydrae brightness ranges from a magnitude of 5.917 to a magnitude of 5.643 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 2.3 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.

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Chi2 Hydrae Facts

Visual Facts


Primary / Proper / Traditional NameChi2 Hydrae
Alternative NamesChi02 Hya, HD 96314, HIP 54255, HR 4317, 265 G. Hydrae, chi02 Hya
Spectral TypeB8V
Multiple Star SystemYes
Star Type main sequence Dwarf Star
Colour blue
GalaxyMilky Way
ConstellationHydra
Absolute Magnitude-1.26 / -0.94
Visual / Apparent Magnitude5.69
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)11h 05m 57.55
Declination (Dec.)-27° 17` 16.1
Galactic Latitude29.97 degrees
Galactic Longitude275.82 degrees
1997 Distance from Earth4.08 Parallax (milliarcseconds)
 799.42 Light Years
 245.10 Parsecs
2007 Distance from Earth4.71 Parallax (milliarcseconds)
 692.49 Light Years
 212.31 Parsecs
Galacto-Centric Distance24,083.90 Light Years / 7,384.00 Parsecs
Proper Motion Dec.-17.04 ± 0.19 milliarcseconds/year
Proper Motion RA.34.76 ± 0.27 milliarcseconds/year
B-V Index-0.06
Radial Velocity30.60 ± 0.90 km/s
Eccentricity0.28
Semi-Major Axis7145.00
Stellar Luminosity (Lsun)301.54
Associated / Clustered StarsChi1 Hydrae

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassEclipsing binary system
Variable Star TypeBeta Lyrae (Sheliak)
Mean Variability Period in Days2.268
Variable Magnitude Range (Brighter - Dimmer)5.643 - 5.917

Estimated Facts


Calculated Effective Temperature10,611 Kelvin

Sources and Links


SIMBAD SourceLink

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