Kappa Coronae Borealis

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Kappa Coronae Borealis
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]
Characteristics
Spectral type K0 III-IV[1]
Astrometry
Parallax (π) 32.13±0.61[1] mas
Distance 101.51 ly
(31.12 pc)
Details
Mass 1.51 (1.32–1.70)[1] M
Radius 5.0 (4.8–5.2) R
Luminosity 12.9 L
Surface gravity (log g) 3.21±0.08 cgs
Temperature 4877±25 K
Metallicity +0.10±0.04
Other designations
κ CrB, 11 CrB, HD 142091, HIP 77655, HR 5901, SAO 64948
Database references
SIMBAD data
Extrasolar Planets
Encyclopaedia
data

Kappa 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.[2] Around 2.5 billion years old, it was formerly an A-type main sequence star.[3]

Dust disk[edit]

In March of 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.[3] The disk extends out to 120 AU.[2]

Planetary system[edit]

In October 2007, a giant planet was found by Johnson et al., who used the radial velocity method.[4] In 2012 it was confirmed.[1]

This planet was assumed to be outside the habitable zone on the assumption that the star is K1IVa.[5] Given the star's luminosity, the planet is more likely on the zone's inner edge.[6]

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.[3]

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

See also[edit]

References[edit]

  1. ^ a b c d e f Bun'ei Sato et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". PASJ. arXiv:1207.3141. Bibcode:2012PASJ...64..135S. doi:10.1093/pasj/64.6.135. 
  2. ^ 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. Bibcode:2014ApJ...792...65P. doi:10.1088/0004-637X/792/1/65. 65. 
  3. ^ 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. 
  4. ^ 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. 
  5. ^ "Planet kappa CrB b". 
  6. ^ 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″