R Coronae Borealis
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 15h 48m 34.4147s |
| Declination | +28° 09′ 24.295″ |
| Apparent magnitude (V) | 5.71 - 14.8 |
| Characteristics | |
| Spectral type | G0Iep |
| U−B color index | 0.13 |
| B−V color index | 0.60 |
| V−R color index | 0.45 |
| J−H color index | 0.275 |
| J−K color index | 0.800 |
| Variable type | R CrB |
| Astrometry | |
| Radial velocity (Rv) | 27.83 km/s |
| Proper motion (μ) | RA: −2.10 mas/yr Dec.: −11.52 mas/yr |
| Parallax (π) | 0.73±0.27 mas |
| Distance | 1,400 pc |
| Absolute magnitude (MV) | −5 |
| Details | |
| Mass | 0.8-0.9 M☉ |
| Radius | 85 R☉ |
| Luminosity | ~10,000 L☉ |
| Surface gravity (log g) | 0.5 cgs |
| Temperature | 6,750 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 | |
| SIMBAD | data |
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.