Pi Coronae Borealis

Pi Coronae Borealis, Latinized from π Coronae Borealis, is a solitary,[6] orange-hued star in the northern constellation of Corona Borealis. Its apparent magnitude is 5.58,[2] which is bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 13.40 mas as measured from Earth, it is located about 243 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −5 km/s.[3] It is most likely (98% chance) a member of the thin disk population.[7]

Pi Coronae Borealis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Borealis
Right ascension  15h 43m 59.29973s[1]
Declination +32° 30′ 56.9047″[1]
Apparent magnitude (V) 5.578[2]
Characteristics
Spectral type G9 III:[2]
B−V color index 1.074[3]
Astrometry
Radial velocity (Rv)−4.94±0.51[3] km/s
Proper motion (μ) RA: −29.92[1] mas/yr
Dec.: −8.85[1] mas/yr
Parallax (π)13.40 ± 0.21[1] mas
Distance243 ± 4 ly
(75 ± 1 pc)
Absolute magnitude (MV)+1.21[4]
Details[3]
Mass1.61[2] M☉
Radius10 R☉
Luminosity39 L☉
Surface gravity (log g)2.7 cgs
Temperature4,667±5 K
Metallicity [Fe/H]−0.15 dex
Rotational velocity (v sin i)3.5 km/s
Age4.6[2] Gyr
Other designations
π CrB, 9 CrB, BD+32° 2621, HD 140716, HIP 77048, HR 5855, SAO 64870[5]
Database references
SIMBADdata

This is an evolved G-type giant star with a stellar classification of G9 III:, where the ':' indicates some uncertainty about the classification. (Bartkevicius and Lazauskaite (1997) classify it as K0 III.)[8] The star has 1.61[2] times the mass of the Sun and has expanded to about 10 times the Sun's radius. The abundance of iron is lower than in the Sun: the star is considered metal deficient.[8] It is around 4.6[2] billion years old and is radiating 39 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,667 K.[3]

References
  1. 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.
  2. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  3. Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
  4. 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.
  5. "pi. CrB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-30.
  6. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  7. Soubiran, C.; et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788.
  8. Bartkevicius, A.; Lazauskaite, R. (December 1997), "Classification of Population II Stars in the Vilnius Photometric System. II. Results", Baltic Astronomy, 6: 499–572, Bibcode:1997BaltA...6..499B, doi:10.1515/astro-1997-0402.
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