Beta Circini

Beta Circini, Latinized from β Circini, is an A-type main sequence star and is the second-brightest star in the constellation of Circinus.[2] It has an apparent visual magnitude of approximately 4.069,[2] which is bright enough to be viewed with the naked eye. Based upon an annual parallax shift of 35.17 mas as seen from the Earth,[2] it is located about 93 light years from the Sun.

β Circini
Location of β Circini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Circinus
Right ascension 15h 17m 30.8488s[1]
Declination −58° 48′ 04.3384″[1]
Apparent magnitude (V) 4.069[2]
Characteristics
Spectral type A3 Va[2]
U−B color index +0.09[3]
B−V color index +0.09[3]
Astrometry
Radial velocity (Rv)9.6 ± 2[2] km/s
Proper motion (μ) RA: −96.742±0.491[1] mas/yr
Dec.: −136.541±0.621[1] mas/yr
Parallax (π)35.1736 ± 0.4253[1] mas
Distance93 ± 1 ly
(28.4 ± 0.3 pc)
Absolute magnitude (MV)+1.64[4]
Details
Radius1.3[5] R☉
Luminosity19[4] L☉
Surface gravity (log g)4.281[6] cgs
Temperature8676±33[7] K
Metallicity [Fe/H]0.16[4] dex
Rotational velocity (v sin i)59[3] km/s
Age370–500[7] Myr
Other designations
β Cir, Beta Circini, Beta Cir, CPD−58 5875, FK5 561, GC 20526, GJ 580.1, GJ 9516, HD 135379, HIP 74824, HR 5670, PPM 343590, SAO 242384.[2]
Database references
SIMBADdata

With a stellar classification of A3 Va,[2] this is an A-type main-sequence star. It is between 370 and 500 million years old[7] with around 1.3[5] times the Sun's radius. The star is radiating 19[4] times the Sun's luminosity from its photosphere at an effective temperature of 8,676 K.[7] It has one known sub-stellar companion.

Planetary System

Beta Circini b is a distant brown dwarf companion orbiting the host star at a distance of 6,656 AU.[8][7] It has a surface temperature of 2,084.0 K. Its mass was estimated using the Spectrum method which concluded that the object has a mass of 56.0±7.0 MJ.[8]

The β Circini planetary system[8]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 56.0 (± 7.0) MJ 6656.0 — — — —

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. "* bet Cir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 5, 2008.
  3. HR 5670, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 5, 2008.
  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, S2CID 119257644.
  5. HD 135379, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line September 5, 2008.
  6. Song, Inseok; et al. (February 2001), "Ages of A-Type Vega-like Stars from uvbyβ Photometry", The Astrophysical Journal, 546 (1): 352–357, arXiv:astro-ph/0010102, Bibcode:2001ApJ...546..352S, doi:10.1086/318269, S2CID 18154947
  7. Smith, L. C.; et al. (2015). "Discovery of a brown dwarf companion to the A3V star β Circini". Monthly Notices of the Royal Astronomical Society. 454 (4): 4476–4483. arXiv:1509.09226. Bibcode:2015MNRAS.454.4476S. doi:10.1093/mnras/stv2290. hdl:2299/16835. S2CID 18570256.
  8. "β Circini b". The Extrasolar Planet Encyclopaedia. Retrieved October 30, 2015.
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