|
R Coronae Borealis |
|
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 15h 48m 34.4149s |
| Declination | +28° 09′ 24.296″ |
| Apparent magnitude (V) | 5.9m |
| Characteristics | |
| Spectral type | G0Iab:pe |
| U−B color index | ? |
| B−V color index | ? |
| Variable type | Variable Star of R CrB type |
| Astrometry | |
| Radial velocity (Rv) | 24.8 km/s |
| Proper motion (μ) | RA: -2.10 mas/yr Dec.: -11.52 mas/yr |
| Parallax (π) | 0.54 ± 0.72 mas |
| Distance | approx. 6000 ly (approx. 2000 pc) |
| Absolute magnitude (MV) | 6.46 |
| Details | |
| Mass | 0.8 M☉ |
| Radius | ? R☉ |
| Luminosity | approx. 8000 L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | ? |
| Age | ? years |
| Other designations | |
| Database references | |
| SIMBAD | data |
R Coronae Borealis is a yellow supergiant star, and is the prototype of the RCB class 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, in the constellation of Corona Borealis, but at intervals of several months to many years fades to as faint as magnitude 14. Over successive months it gradually returns to its normal brightness, giving it the nickname "Fade-Out star," or "Reverse Nova".
The cause of this behaviour is believed to be a regular build-up of carbon dust in the star's atmosphere. The sudden drop in brightness may be caused by a rapid condensation of dust, resulting in much of the star's light being blocked. The gradual restoration to normal brightness results from the dust being dispersed by radiation pressure.
Variability of R CrB has been discovered by the English astronomer, Edward Pigott in 1795.[1][2] It was known as Variabilis Coronae,[3] "Variable of Corona".
|
||||||||||||||