R Coronae Borealis
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R Coronae Borealis |
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| Observation data Epoch J2000 |
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|---|---|
| Constellation (pronunciation) |
Corona Borealis |
| Right ascension | 15h 48m 34.4149s |
| Declination | +28° 09' 24.296"' |
| Apparent magnitude (V) | 5.9 |
| 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 | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | ? |
| Age | ? years |
| Other designations | |
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V* R CrB, GSC2 N1330022410, 2MASS J15483440+2809242, AG+28° 1513, GSC 02039-01605, N30 3552, TD1 18592, BD+28° 2477, HD 141527, PLX 3581, TYC 2039-1605-1, EM* CDS 886, HIC 77442, PPM 104338, GC 21257, HIP 77442, RAFGL 4219, YZ 28 7350, GCRV 9116, HR 5880, ROT 2225, AAVSO 1544+28A, IRAS 15465+2818, SAO 84015.
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| 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.
[edit] External links
- SEDS page
- AAVSO page
- Entry in the Encyclopedia of Astrobiology, Astronomy, and Spaceflight
- http://jumk.de/astronomie/special-stars/r-cor-bor.shtml
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