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U Antliae, HD91793, HIP51821, HR4153

U Antliae is a carbon red pulsating variable star that can be located in the constellation of Antlia. 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.

U Antliae's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR4153. HIP51821 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD91793.

U Antliae has alternative name(s) :- , U Ant.

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

Location of U Antliae

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 U Antliae, the location is 10h 35m 12.88 and -39° 33` 45.3 .

Proper Motion of U Antliae

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 3.50 ± 0.39 miliarcseconds/year towards the north and -31.02 ± 0.54 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 41.00000 km/s with an error of about 4.40 km/s .

Physical Properties (Colour, Temperature) of U Antliae

U Antliae has a spectral type of C. This means the star is a carbon red variable star. The star is 7,377.00 Parsecs from the Galactic Centre or terms of Light Years is 24,061.07 s. The star has a B-V Colour Index of 3.01 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 0 Kelvin.

U Antliae Apparent and Absolute Magnitudes

U Antliae has an apparent magnitude of 5.50 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 -1.54 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.64. 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 Antliae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.90 which gave the calculated distance to U Antliae as 836.32 light years away from Earth or 256.41 parsecs. It would take a spaceship travelling at the speed of light, 836.32 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 3.73 which put U Antliae at a distance of 874.43 light years or 268.10 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 7,377.00 Parsecs or 24,061.07 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 U Antliae

The star is a pulsating Slow Irregular 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 Antliae brightness ranges from a magnitude of 5.699 to a magnitude of 5.261 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.4 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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U Antliae Facts

Visual Facts


Primary / Proper / Traditional NameU Antliae
Alternative NamesU Ant, HD 91793, HIP 51821, HR 4153, U Ant
Spectral TypeC
Multiple Star SystemNo / Unknown
Star TypeVariable Star
Colour carbon red
GalaxyMilky Way
ConstellationAntlia
Absolute Magnitude-1.54 / -1.64
Visual / Apparent Magnitude5.50
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)10h 35m 12.88
Declination (Dec.)-39° 33` 45.3
Galactic Latitude16.14 degrees
Galactic Longitude276.22 degrees
1997 Distance from Earth3.90 Parallax (milliarcseconds)
 836.32 Light Years
 256.41 Parsecs
2007 Distance from Earth3.73 Parallax (milliarcseconds)
 874.43 Light Years
 268.10 Parsecs
Galacto-Centric Distance24,061.07 Light Years / 7,377.00 Parsecs
Proper Motion Dec.3.50 ± 0.39 milliarcseconds/year
Proper Motion RA.-31.02 ± 0.54 milliarcseconds/year
B-V Index3.01
Radial Velocity41.00 ± 4.40 km/s
Eccentricity0.29
Semi-Major Axis5490.00

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.419
Variable Magnitude Range (Brighter - Dimmer)5.261 - 5.699

Estimated Facts


Sources and Links


SIMBAD SourceLink

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