Kappa Coronae Borealis
Star in the constellation Corona Borealis
From Wikipedia, the free encyclopedia
Kappa Coronae Borealis, Latinized from κ Coronae Borealis, is a star 98 light years away in the constellation of Corona Borealis. The apparent magnitude is +4.82 (4.17 trillion times fainter than the Sun) and the absolute magnitude is +2.35 (9.82 times brighter than the Sun). It is an evolved K-type star of spectral type K1IV, meaning it has completely exhausted its hydrogen supply at its core. It is 1.32 times as massive as the Sun yet has brightened to 11.6 times its luminosity. Around 2.5 billion years old, it was formerly an A-type main sequence star.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Corona Borealis[1] |
| Right ascension | 15h 51m 13.9313s[2] |
| Declination | +35° 39â² 26.574â³[2] |
| Apparent magnitude (V) | +4.79[3] |
| Characteristics | |
| Evolutionary stage | red giant branch[4][2] |
| Spectral type | K0 III-IV[3] |
| Astrometry | |
| Proper motion (μ) | RA: â8.669[2] mas/yr Dec.: â348.350[2] mas/yr |
| Parallax (Ï) | 33.3433±0.0800 mas[2] |
| Distance | 97.8 ± 0.2 ly (29.99 ± 0.07 pc) |
| Absolute magnitude (MV) | +2.37[1] |
| Details[4] | |
| Mass | 1.32±0.10 Mâ |
| Radius | 4.77±0.07 Râ |
| Luminosity | 11.6±0.3 Lâ |
| Surface gravity (log g) | 3.15±0.14 cgs |
| Temperature | 4,870±47 K |
| Metallicity [Fe/H] | +0.13±0.03 dex |
| Other designations | |
| κ CrB, 11 CrB, HD 142091, HIP 77655, HR 5901, SAO 64948[5] | |
| Database references | |
| SIMBAD | data |
Dust disk
Planetary system
In October 2007, a giant planet was found by Johnson et al., who used the radial velocity method.[8] In 2012 it was confirmed.[3]
This planet was assumed to be outside the habitable zone on the assumption that the star is K1IVa.[9] Given the star's luminosity, the planet is more likely on the zone's inner edge.[10]
The width of the circumstellar belt suggests the presence of a second planetary companion of the star, either within it or between two narrower belts.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | â¥1.811±0.057 MJ | 2.65±0.13 | 1285±14 | 0.167±0.032 | â | â |