R Coronae Borealis

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
Location of R Coronae Borealis (circled)
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]
Distance1,400[9] pc
Absolute magnitude (MV)−5[9]
Details
Mass0.8-0.9[10] M☉
Radius85[9] R☉
Luminosity~10,000[11] L☉
Surface gravity (log g)0.5[12] cgs
Temperature6,750[11] K
Other designations
R Coronae Borealis, R CrB, GSC2 N1330022410, 2MASS J15483440+2809242, AG+28° 1513, GSC 02039-01605, BD+28° 2477, HD 141527, PLX 3581, TYC 2039-1605-1, CDS 886, PPM 104338, GC 21257, HIP 77442, RAFGL 4219, GCRV 9116, HR 5880, AAVSO 1544+28A, IRAS 15465+2818, SAO 84015.
Database references
SIMBADdata

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.

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