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R Ursae Majoris, HD92763, HIP52546

R Ursae Majoris is a red pulsating star that can be located in the constellation of UrsaMajor. The star can not be seen by the naked eye, you need a telescope to see it.

HIP52546 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD92763.

R Ursae Majoris has alternative name(s), R UMa.

Location of R Ursae Majoris

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 R Ursae Majoris, the location is 10h 44m 38.54 and +68d 46` 32.9 .

Proper Motion of R Ursae Majoris

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 -22.66 ± 0.68 miliarcseconds/year towards the north and -40.51 ± 1.06 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 10.00000 km/s with an error of about 15.10 km/s .

Physical Properties (Colour, Temperature, Radius) of R Ursae Majoris

R Ursae Majoris has a spectral type of M3e-M9e. This means the star is a red 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.

R Ursae Majoris Radius has been calculated as being 6.39 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,448,458.38.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 8.55. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

R Ursae Majoris Apparent and Absolute Magnitudes

R Ursae Majoris has an apparent magnitude of 9.86 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 2.40 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.77. 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 R Ursae Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.22 which gave the calculated distance to R Ursae Majoris as 1012.93 light years away from Earth or 310.56 parsecs. It would take a spaceship travelling at the speed of light, 1012.93 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 2.41 which put R Ursae Majoris at a distance of 1353.37 light years or 414.94 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 R Ursae Majoris

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. R Ursae Majoris brightness ranges from a magnitude of 11.027 to a magnitude of 6.846 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 299.7 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.

R Ursae Majoris Facts

Alternative Names

Traditional/Proper NameR Ursae Majoris
Short NameR UMa
Hipparcos Library I.D.52546
Bonner DurchmusterungBD+69 587
Henry Draper Designation92763

Visual Facts

Star Type star
ConstellationUrsa Major
Absolute Magnitude2.40 / 1.77
Visual / Apparent Magnitude9.86
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)10h 44m 38.54
Declination (Dec.)+68d 46` 32.9
Galactic Latitude44.36 degrees
Galactic Longitude138.36 degrees
1997 Distance from Earth3.22 Parallax (milliarcseconds)
 1012.93 Light Years
 310.56 Parsecs
2007 Revised Distance from Earth2.41 Parallax (milliarcseconds)
 1353.37 Light Years
 414.94 Parsecs
Proper Motion Dec.-22.66 ± 0.68 milliarcseconds/year
Proper Motion RA.-40.51 ± 1.06 milliarcseconds/year
B-V Index1.50
Radial Velocity10.00 ± 15.10 km/s
Spectral TypeM3e-M9e
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days299.700
Variable Magnitude Range (Brighter - Dimmer)6.846 - 11.027

Estimated Facts

Calculated Effective Temperature4,014 Kelvin

Sources and Links

SIMBAD SourceLink

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