Astronomy:Kappa Coronae Borealis

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Short description: Star in the constellation Corona Borealis
Kappa Coronae Borealis
Location of κ Coronae Borealis (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Corona Borealis[1]
Right ascension  15h 51m 13.9313s[2]
Declination +35° 39′ 26.574″[2]
Apparent magnitude (V) +4.79[3]
Characteristics
Evolutionary stage red giant branch[4][2]
Spectral type K0 III-IV[3]
B−V color index 0.996±0.005[1]
Astrometry
Radial velocity (Rv)−25.16±0.13[5] km/s
Proper motion (μ) RA: −8.669[2] mas/yr
Dec.: −348.350[2] mas/yr
Parallax (π)33.3433 ± 0.0800[2] mas
Distance97.8 ± 0.2 ly
(29.99 ± 0.07 pc)
Absolute magnitude (MV)+2.37[1]
Details[4]
Mass1.32±0.10 M☉
Radius4.77±0.07 R☉
Luminosity11.6±0.3 L☉
Surface gravity (log g)3.15±0.14 cgs
Temperature4,870±47 K
Metallicity [Fe/H]+0.13±0.03 dex
Other designations
κ CrB, 11 CrB, HD 142091, HIP 77655, HR 5901, SAO 64948[6]
Database references
SIMBADdata

Kappa Coronae Borealis is a star in the northern constellation of Corona Borealis. Its name is a Bayer designation that is Latinized from κ Coronae Borealis, and abbreviated Kappa CrB or κ CrB. The star is visible to the naked eye with an apparent visual magnitude of +4.82.[3] Based on parallax measurements, it is located at a distance of 97.8 light-years (30.0 pc) from the Earth. The star is drifting closer to the Sun with a line of sight velocity component of −25 km/s.[5]

This is an evolved K-type star of spectral type K0 III-IV,[3] meaning it has completely exhausted its hydrogen supply at its core. Around 2.5 billion years old,[4] it was an A-type main sequence star.[7] It is 1.32 times as massive as the Sun and has expanded to 4.8 times the Sun's radius. The star is radiating 11.6 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,870 K.[4]

Dust disk

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.[7] The disk extends out from 50 AU to 180 AU, and there is an estimated 0.016 M⊕ of dust.[8]

Planetary system

In October 2007, a giant planet was found by Johnson et al., who used the radial velocity method.[9] In 2012 it was confirmed.[3]

This planet was assumed to be outside the habitable zone on the assumption that the star is K1IVa.[10] Given the star's luminosity, the planet is more likely on the zone's inner edge.[11]

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.[7]

The Kappa Coronae Borealis planetary system[12]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥1.811±0.057 MJ 2.65±0.13 1285±14 0.167±0.032 — —

See also

  • List of extrasolar planets

References

  1. ↑ 1.0 1.1 1.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Sato, Bun'ei et al. (2012). "Substellar Companions to Seven Evolved Intermediate-Mass Stars". Publications of the Astronomical Society of Japan 64 (6): 135. doi:10.1093/pasj/64.6.135. Bibcode: 2012PASJ...64..135S. https://academic.oup.com/pasj/article/64/6/135/1422181. 
  4. ↑ 4.0 4.1 4.2 4.3 White, T. R. et al. (July 2018). "Interferometric diameters of five evolved intermediate-mass planet-hosting stars measured with PAVO at the CHARA Array". Monthly Notices of the Royal Astronomical Society 477 (4): 4403–4413. doi:10.1093/mnras/sty898. Bibcode: 2018MNRAS.477.4403W. 
  5. ↑ 5.0 5.1 Jofré, E. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics 574: A50. doi:10.1051/0004-6361/201424474. Bibcode: 2015A&A...574A..50J. 
  6. ↑ "Kappa Coronae Borealis". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Kappa+Coronae+Borealis. 
  7. ↑ 7.0 7.1 7.2 Bonsor, Amy (2013). "Spatially resolved images of dust belt(s) around the planet-hosting subgiant κ CrB". MNRAS 431 (4): 3025–3035. doi:10.1093/mnras/stt367. Bibcode: 2013MNRAS.431.3025B. 
  8. ↑ Lovell, J. B. et al. (2022). "High-resolution ALMA and HST imaging of κ CrB: A broad debris disc around a post-main-sequence star with low-mass companions". Monthly Notices of the Royal Astronomical Society 517 (2): 2546–2566. doi:10.1093/mnras/stac2782. Bibcode: 2022MNRAS.517.2546L. 
  9. ↑ Johnson, John Asher 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. doi:10.1086/526453. Bibcode: 2008ApJ...675..784J. 
  10. ↑ "Planet kappa CrB b". http://exoplanet.hanno-rein.de/system.php?id=kappa+CrB+b. 
  11. ↑ An earth-analogue should be slightly more than 3 AU away: square root of luminosity 12.9.
  12. ↑ Luhn, Jacob K. et al. (2019). "Retired A Stars and Their Companions. VIII. 15 New Planetary Signals around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts". The Astronomical Journal 157 (4): 149. doi:10.3847/1538-3881/aaf5d0. Bibcode: 2019AJ....157..149L. 

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



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