Universe Guide


10 Hydrae - HD74591 - HIP42931

10 Hydrae is a blue main sequence dwarf star that can be located in the constellation of Hydra. HIP42931 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD74591. The Id of the star in the Gould Star Catalogue is 52. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major. 10 Hydrae has alternative name(s), 10 Hydrae , 10 Hya.

Location of 10 Hydrae

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 10 Hydrae, the location is 08h 45m 01.28 and +05d40`50.1 .

Proper Motion of 10 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 -004.80 ± 000.23 towards the north and 002.05 ± 000.41 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 10 Hydrae

10 Hydrae has a spectral type of A6V. This means the star is a blue coloured main sequence dwarf star. The star has a B-V Colour Index of 0.2 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,767 Kelvin.

10 Hydrae has been calculated as 1.94 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,351,638.04.km.

10 Hydrae Apparent and Absolute Magnitudes

10 Hydrae has an apparent magnitude of 6.13 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 2.12 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.08. 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 10 Hydrae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 15.78 which gave the calculated distance to 10 Hydrae as 206.69 light years away from Earth or 63.37 parsecs. In 2007, Hipparcos data was revised with a new parallax of 15.49 which put 10 Hydrae at a distance of 210.56 light years or 64.56 parsecs.

It would take a spaceship travelling at the speed of light, 206.69 years using the 1997 distance to get there. We don't have the technology or spaceship that can carry people over that distance yet.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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10 Hydrae Facts

Alternative Names

Traditional Name10 Hydrae
Short Name10 Hya
Alternative Name(s)10 Hydrae
Hipparcos Library I.D.42931
Bonner DurchmusterungBD+06 2030
Gould I.D.52
Henry Draper Designation74591

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude2.12 / 2.08
Apparent Magnitude6.13
Right Ascension (R.A.)08h 45m 01.28
Declination (Dec.)+05d40`50.1
1997 Distance from Earth15.78 Parallax (milliarcseconds)
 206.69 Light Years
 63.37 Parsecs
2007 Distance from Earth15.49 Parallax (milliarcseconds)
 210.56 Light Years
 64.56 Parsecs
Proper Motion Dec.-4.80 ± 0.23 milliarcseconds/year
Proper Motion RA.2.05 ± 0.41 milliarcseconds/year
B-V Index0.20
Spectral TypeA6V
Colour(A) blue

Estimated Facts

Radius (x the Sun)1.94
Calculated Effective Temperature7,767 Kelvin

Sources and Links

SIMBAD SourceLink

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