Universe Guide


25 Hydrae - HD80105 - HIP45588

25 Hydrae is a orange to red star that can be located in the constellation of Hydra. HIP45588 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD80105. 25 Hydrae has alternative name(s), 25 Hydrae , 25 Hya.

Location of 25 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 25 Hydrae, the location is 09h 17m 29.22 and -11d57`42.7 .

Proper Motion of 25 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 -041.69 ± 000.45 towards the north and -032.78 ± 000.65 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 25 Hydrae

25 Hydrae has a spectral type of K0. This means the star is a orange to red star. The star has a B-V Colour Index of 1.03 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,908 Kelvin.

25 Hydrae has been calculated as 6.47 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,503,643.40.km.

25 Hydrae Apparent and Absolute Magnitudes

25 Hydrae has an apparent magnitude of 7.07 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 1.50 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.02. 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 25 Hydrae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.68 which gave the calculated distance to 25 Hydrae as 424.69 light years away from Earth or 130.21 parsecs. It would take a spaceship travelling at the speed of light, 424.69 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 6.18 which put 25 Hydrae at a distance of 527.77 light years or 161.81 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.

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.

25 Hydrae Facts

Alternative Names

Traditional Name25 Hydrae
Short Name25 Hya
Alternative Name(s)25 Hydrae
Hipparcos Library I.D.45588
Bonner DurchmusterungBD-11 2601
Henry Draper Designation80105

Visual Facts

Star Type star
Absolute Magnitude1.50 / 1.02
Apparent Magnitude7.07
Right Ascension (R.A.)09h 17m 29.22
Declination (Dec.)-11d57`42.7
1997 Distance from Earth7.68 Parallax (milliarcseconds)
 424.69 Light Years
 130.21 Parsecs
2007 Revised Distance from Earth6.18 Parallax (milliarcseconds)
 527.77 Light Years
 161.81 Parsecs
Proper Motion Dec.-41.69 ± 0.45 milliarcseconds/year
Proper Motion RA.-32.78 ± 0.65 milliarcseconds/year
B-V Index1.03
Spectral TypeK0
Colour(K) Orange to Red

Estimated Facts

Radius (x the Sun)6.47
Calculated Effective Temperature4,908 Kelvin

Sources and Links

SIMBAD SourceLink

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