RR Coronae Borealis is a red pulsating star that can be located in the constellation of CoronaBorealis. RR Coronae Borealis is the brightest star in Corona Borealis based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.
HIP76844 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD140297.
RR Coronae Borealis has alternative name(s), RR CrB.
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 RR Coronae Borealis, the location is 15h 41m 26.21 and +38d 33` 26.9 .
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 -32.44 ± 0.46 miliarcseconds/year towards the north and 20.24 ± 0.53 miliarcseconds/year east if we saw them in the horizon.
RR Coronae Borealis has a spectral type of M5. This means the star is a red star. The star is 7314.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23855.5869801600000000s. The star has a B-V Colour Index of 1.31 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,369 Kelvin.
RR Coronae Borealis Radius has been calculated as being 13.19 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 9,175,277.85.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 16.52. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.
RR Coronae Borealis has an apparent magnitude of 7.64 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 0.46 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.03. 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 3.67 which gave the calculated distance to RR Coronae Borealis as 888.73 light years away from Earth or 272.48 parsecs. It would take a spaceship travelling at the speed of light, 888.73 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 2.93 which put RR Coronae Borealis at a distance of 1113.19 light years or 341.30 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 7,314.00 Parsecs or 23,855.59 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.
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. RR Coronae Borealis brightness ranges from a magnitude of 7.526 to a magnitude of 7.267 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 59.8 days (variability).
|Traditional/Proper Name||RR Coronae Borealis|
|Short Name||RR CrB|
|Hipparcos Library I.D.||76844|
|Bonner Durchmusterung||BD+39 2901|
|Henry Draper Designation||140297|
|Absolute Magnitude||0.46 / -0.03|
|Visual / Apparent Magnitude||7.64|
|Naked Eye Visible||Requires a 7x50 Binoculars - Magnitudes|
|Right Ascension (R.A.)||15h 41m 26.21|
|Declination (Dec.)||+38d 33` 26.9|
|Galactic Latitude||52.88 degrees|
|Galactic Longitude||61.85 degrees|
|1997 Distance from Earth||3.67 Parallax (milliarcseconds)|
|888.73 Light Years|
|2007 Revised Distance from Earth||2.93 Parallax (milliarcseconds)|
|1113.19 Light Years|
|Galacto-Centric Distance||23,855.59 Light Years / 7,314.00 Parsecs|
|Proper Motion Dec.||-32.44 ± 0.46 milliarcseconds/year|
|Proper Motion RA.||20.24 ± 0.53 milliarcseconds/year|
|Radial Velocity||-58.39 ± 1.44 km/s|
|Variable Star Class||Pulsating|
|Variable Star Type||Semiregular late- (M, C, S or Me, Ce, Se) giants with poorly defined periodicity|
|Mean Variability Period in Days||59.800|
|Variable Magnitude Range (Brighter - Dimmer)||7.267 - 7.526|
|Calculated Effective Temperature||4,369 Kelvin|
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. Id||B.D. Id||Star Code||Magnitude||R.A.||Dec.||Spectrum||Colour||Year|