Universe Guide


U Hydrae - HD92055 - HIP52009

U Hydrae is a pulsating star that can be located in the constellation of Hydra. HIP52009 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD92055. The Id of the star in the Gould Star Catalogue is 240. 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. U Hydrae has alternative name(s), U_Hya.

Location of U Hydrae


Proper Motion of U 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 -037.72 ± 000.16 towards the north and 042.59 ± 000.23 east if we saw them in the horizon.

Physical Properties (Temperature, Radius) of U Hydrae

U Hydrae has a spectral type of C. This means the star is a star. The star has a B-V Colour Index of 2.8 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 0 Kelvin.

U Hydrae Apparent and Absolute Magnitudes

U Hydrae has an apparent magnitude of 4.89 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 -1.16 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.70. 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 U Hydrae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 6.18 which gave the calculated distance to U Hydrae as 527.77 light years away from Earth or 161.81 parsecs. It would take a spaceship travelling at the speed of light, 527.77 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 4.80 which put U Hydrae at a distance of 679.51 light years or 208.33 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.

Variable Type of U Hydrae

The star is a pulsating Semiregular late- (M, C, S or Me, Ce, Se) giants with poorly defined periodicity 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. U Hydrae brightness ranges from a magnitude of 5.000 to a magnitude of 5.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 115.0 days (variability).

Source of Information


U Hydrae Facts

Alternative Names

Traditional NameU Hydrae
Short NameU Hya
Hipparcos Library I.D.52009
Bonner DurchmusterungBD-12 3218
Gould I.D.240
Henry Draper Designation92055

Visual Facts

Star Type star
Absolute Magnitude-1.16 / -1.70
Apparent Magnitude4.89
Right Ascension (R.A.)10h 37m 33.25
Declination (Dec.)-13d23`04.0
1997 Distance from Earth6.18 Parallax (milliarcseconds)
 527.77 Light Years
 161.81 Parsecs
2007 Revised Distance from Earth4.80 Parallax (milliarcseconds)
 679.51 Light Years
 208.33 Parsecs
Proper Motion Dec.-37.72 ± 0.16 milliarcseconds/year
Proper Motion RA.42.59 ± 0.23 milliarcseconds/year
B-V Index2.80
Spectral TypeC

Variable Star Details

Variable Star ClassPulsating
Mean Variability Period in Days115.000

Estimated Facts

Sources and Links

SIMBAD SourceLink

Related Stars

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