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Alula Australis (Xi Ursae Majoris) - HD98230 - HIP55203 - HR4375

Alula Australis (Xi Ursae Majoris) is a white to yellow main sequence dwarf star that can be located in the constellation of UrsaMajor. Alula Australis is the brightest star in Ursa Major based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Xi Ursae Majoris is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR4375. HIP55203 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD98230. The Gliese ID of the star is Gliese GL423A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Ref : Star Names.

Alula Australis has alternative name(s), 53 Ursae Majoris , 53 UMa.

Location of Alula Australis

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 Alula Australis, the location is 11h 18m 11.24 and +31 d 31 ` 50.8 .

Alula Australis 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 1.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of Alula Australis

Alula Australis has a spectral type of G0V. This means the star is a white to yellow main sequence dwarf star. The star has a B-V Colour Index of 0.6 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,895 Kelvin.

Alula Australis Apparent and Absolute Magnitudes

Alula Australis has an apparent magnitude of 3.79 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. 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.

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.

Alula Australis Facts

Alternative Names

Traditional/Proper NameAlula Australis
Short Name53 UMa
Bayer DesignationXi Ursae Majoris
Alternative Name(s)53 Ursae Majoris
Hipparcos Library I.D.55203
Yale Bright Star Catalogue (HR) Id4375
Bonner DurchmusterungBDD+32 2132
Gliese ID423A
Henry Draper Designation98230

Visual Facts

Star Typemain sequence dwarf star
Visual / Apparent Magnitude3.79
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)11h 18m 11.24
Declination (Dec.)+31 d 31 ` 50.8
B-V Index0.60
Spectral TypeG0V
Colour(G) White to Yellow

Estimated Facts

Luminosity (x the Sun)1.0000000
Calculated Effective Temperature5,895 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
98231+32 2132.0A4.40000-429.00000-586.00000G0Yellow
98230B4.90000G0Yellow1826

Location of Alula Australis in Ursa Major


Alula Australis (Xi Ursae Majoris) Location in Ursa Major

The map was generated using Night Vision, an awesome free application by Brian Simpson.


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