Kappa Coronae Borealis

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κ Coronae Borealis
Corona Borealis constellation map.svg
Red circle.svg
Location of κ Coronae Borealis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Corona Borealis
Right ascension 15h 51m 13.9315s
Declination +35° 39′ 26.575″
Apparent magnitude (V) +4.79[1]
Spectral type K0 III-IV[1]
Parallax (π)32.13±0.61[1] mas
Distance101.51 ly
(31.12 pc)
Absolute magnitude (MV)+2.37[2]
Details[citation needed]
Mass1.51 (1.32–1.70)[1] M
Radius5.0 (4.8–5.2) R
Luminosity13.6[2] L
Surface gravity (log g)3.21±0.08 cgs
Temperature4,877±25 K
Metallicity [Fe/H]0.08±0.02[2] dex
Other designations
κ CrB, 11 CrB, HD 142091, HIP 77655, HR 5901, SAO 64948
Database references
Extrasolar Planets

Kappa Coronae Borealis, Latinized from κ Coronae Borealis, is a star approximately 102 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 orange K-type subgiant star of spectral type K1IV, meaning it has nearly completely exhausted its hydrogen supply in its core. It is 1.94 times as massive as the Sun yet has brightened to 12.5 times its luminosity.[3] Around 2.5 billion years old, it was formerly an A-type main sequence star.[4]

Dust disk[edit]

In March 2013, it was announced that resolved images of at least one dust disk surrounding Kappa Coronae Borealis were captured, making it the first subgiant to host such circumstellar belt.[4] The disk extends out to 120 AU.[3]

Planetary system[edit]

In October 2007, a giant planet was found by Johnson et al., who used the radial velocity method.[5] In 2012 it was confirmed.[1]

This planet was assumed to be outside the habitable zone on the assumption that the star is K1IVa.[6] Given the star's luminosity, the planet is more likely on the zone's inner edge.[7]

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.[4]

The Kappa Coronae Borealis planetary system[1]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b >1.6 MJ 2.6 1251 ± 15 0.073 ± 0.049

See also[edit]


  1. ^ a b c d e f Sato, Bun'ei; et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". Publications of the Astronomical Society of Japan. 64 (6). 135. arXiv:1207.3141. Bibcode:2012PASJ...64..135S. doi:10.1093/pasj/64.6.135.
  2. ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  3. ^ a b Pawellek, Nicole; Krivov, Alexander V.; Marshall, Jonathan P.; Montesinos, Benjamin; Ábrahám, Péter; Moór, Attila; Bryden, Geoffrey; Eiroa, Carlos (2014). "Disk Radii and Grain Sizes in Herschel-resolved Debris Disks". The Astrophysical Journal. 792 (1): 19. arXiv:1407.4579. Bibcode:2014ApJ...792...65P. doi:10.1088/0004-637X/792/1/65. 65.
  4. ^ a b c Bonsor, Amy; et al. (2013). "Spatially resolved images of dust belt(s) around the planet-hosting subgiant κ CrB". MNRAS. 431: 3025–3035. arXiv:1302.7000. Bibcode:2013MNRAS.431.3025B. doi:10.1093/mnras/stt367.
  5. ^ Johnson; et al. (2008). "Retired A Stars and Their Companions. II. Jovian Planets Orbiting κ CrB and HD 167042". The Astrophysical Journal. 675 (1): 784–789. arXiv:0711.4367. Bibcode:2008ApJ...675..784J. doi:10.1086/526453.
  6. ^ "Planet kappa CrB b".[permanent dead link]
  7. ^ An earth-analogue should be slightly more than 3 AU away: square root of luminosity 12.9.

Coordinates: Sky map 15h 51m 13.9315s, +35° 39′ 26.575″