HIP81309 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD149234.
X Arae has alternative name(s) :- X Ara, X Ara.
More details on star alternative names can be found at Star Names .
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 X Arae, the location is 16h 36m 24.67 and -55° 24` 53.1 .
X Arae has a spectral type of Md. This means the star is a red variable star. The star has a B-V Colour Index of 1.5 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,014 Kelvin.
X Arae has an apparent magnitude of 9.87 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -2.04 which gave the calculated distance to X Arae as -1598.84 light years away from Earth or -490.20 parsecs. It would take a spaceship travelling at the speed of light, -1598.84 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is a pulsating Omicron Ceti 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. X Arae brightness ranges from a magnitude of 12.896 to a magnitude of 9.050 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 175.4 days (variability).
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.
|Primary / Proper / Traditional Name||X Arae|
|Alternative Names||X Ara, HD 149234, HIP 81309, X Ara|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Variable Star|
|Visual / Apparent Magnitude||9.87|
|Naked Eye Visible||Requires a 7x50 Binoculars - Magnitudes|
|Right Ascension (R.A.)||16h 36m 24.67|
|Declination (Dec.)||-55° 24` 53.1|
|Galactic Latitude||-5.43 degrees|
|Galactic Longitude||331.23 degrees|
|Distance from Earth||-2.04 Parallax (milliarcseconds)|
|-1598.84 Light Years|
|-101,110,303.48 Astronomical Units|
|Radial Velocity||-8.00 ± 999.00 km/s|
|Variable Star Class||Pulsating|
|Variable Star Type||Omicron Ceti|
|Mean Variability Period in Days||175.400|
|Variable Magnitude Range (Brighter - Dimmer)||9.050 - 12.896|
|Calculated Effective Temperature||4,014 Kelvin|
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