Omicron Coronae Borealis
Star in the constellation Corona Borealis
Omicron Coronae Borealis , Latinized from o Coronae Borealis, is a star in the northern constellation of Corona Borealis . It is a faint star but visible to the naked eye on a dark night with an apparent visual magnitude of +5.53.[2] The annual parallax shift of the star as seen from Earth is 12.08 mas , which provides a distance estimate of around 270 light years . It is moving closer to the Sun with a radial velocity of −54 km/s.[4]
Based upon the spectrum of this star, it has a stellar classification of K0 III.[3] This indicates this is an evolved K-type giant star that has exhausted the hydrogen at its core and has left the main sequence . This is a red clump star, which means it is now generating energy through helium fusion at its core . It has 107% of the mass of the Sun and has expanded to over ten times the Sun's radius . The star is radiating 50 times the Sun's luminosity from its expanded photosphere at an effective temperature of 4,812 K.[5]
Planetary system
Omicron Coronae Borealis has one confirmed planet, believed to be, along with HD 100655 b , one of the two least massive planets known around red clump giants.[5] The planet was detected by measuring changes in radial velocity of the host star caused by gravitational perturbation of the orbiting object. It is orbiting with a period of 188 days, at a semimajor axis 83% of the mean separation between the Earth and the Sun, and an eccentricity of 0.19.[5]
References
^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics , 474 (2): 653–664, arXiv :0708.1752 , Bibcode :2007A&A...474..653V , doi :10.1051/0004-6361:20078357 , S2CID 18759600 . Vizier catalog entry
^ a b c d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society , 172 (3): 667–679, Bibcode :1975MNRAS.172..667J , doi :10.1093/mnras/172.3.667 .
^ 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 , S2CID 119257644 .
^ a b c Jofré, E; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics , 574 : A50, arXiv :1410.6422 , Bibcode :2015A&A...574A..50J , doi :10.1051/0004-6361/201424474 , S2CID 53666931 , A50.
^ a b c d 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 , S2CID 119197073 .