R Coronae Borealis
Variable star in the constellation Corona Borealis / From Wikipedia, the free encyclopedia
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This article is about the star. For the star type, see R Coronae Borealis variable.
Not to be confused with RR Coronae Borealis or Rho Coronae Borealis.
R Coronae Borealis is a low-mass yellow supergiant star in the constellation of Corona Borealis. It is the prototype of the R Coronae Borealis variable of variable stars, which fade by several magnitudes at irregular intervals. R Coronae Borealis itself normally shines at approximately magnitude 6, just about visible to the naked eye, but at intervals of several months to many years fades to as faint as 15th magnitude. Over successive months it then gradually returns to its normal brightness, giving it the nickname "reverse nova", after the more common type of star which rapidly increases in brightness before fading.
Quick Facts Observation data Epoch J2000.0 Equinox J2000.0, Constellation ...
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Corona Borealis |
Right ascension | 15h 48m 34.4147s[1] |
Declination | +28° 09′ 24.295″[1] |
Apparent magnitude (V) | 5.71 - 14.8[2] |
Characteristics | |
Spectral type | G0Iep[3] |
U−B color index | 0.13[4] |
B−V color index | 0.60[4] |
V−R color index | 0.45[4] |
J−H color index | 0.275[5] |
J−K color index | 0.800[5] |
Variable type | R CrB[6][2] |
Astrometry | |
Radial velocity (Rv) | 27.83[7] km/s |
Proper motion (μ) | RA: -2.10[8] mas/yr Dec.: −11.52[8] mas/yr |
Parallax (π) | 0.73 ± 0.27 mas[1] |
Distance | 1,400[9] pc |
Absolute magnitude (MV) | −5[9] |
Details | |
Mass | 0.8-0.9[10] M☉ |
Radius | 85[9] R☉ |
Luminosity | ~10,000[11] L☉ |
Surface gravity (log g) | 0.5[12] cgs |
Temperature | 6,750[11] K |
Other designations | |
Database references | |
SIMBAD | data |
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