27 Arietis

27 Arietis is a binary star[4] system in the northern constellation of Aries. 27 Arietis is the Flamsteed designation. It is a dim, yellow-hued star that is close to the lower limit of what can be viewed with the naked eye, having an apparent visual magnitude is 6.21.[2] The annual parallax shift of 11.64±0.12 mas[1] corresponds to a physical distance of approximately 280 light-years (86 parsecs) from Earth. It is advancing closer to the Earth with a heliocentric radial velocity of −122.7 km/s, and may come as close as 84 light-years in around 643,000 years.[2]

27 Arietis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aries
Right ascension  02h 30m 54.39715s[1]
Declination +17° 42′ 13.8908″[1]
Apparent magnitude (V) 6.21[2]
Characteristics
Spectral type G8 III-IV Fe-2[3]
B−V color index 0.908±0.002[2]
Astrometry
Radial velocity (Rv)−122.71±0.28[2] km/s
Proper motion (μ) RA: +33.774[1] mas/yr
Dec.: −82.912[1] mas/yr
Parallax (π)11.6403 ± 0.1172[1] mas
Distance280 ± 3 ly
(85.9 ± 0.9 pc)
Absolute magnitude (MV)1.48[2]
Orbit[4]
Period (P)130.706±0.008 d
Eccentricity (e)0.366±0.007
Periastron epoch (T)53,480.1±0.4 MJD
Argument of periastron (ω)
(secondary)		275.5±0.7°
Semi-amplitude (K1)
(primary)		5.98±0.05 km/s
Details
Mass1.29[5] M☉
Radius7.04+0.29
−0.28 R☉
Luminosity28.43[2] L☉
Surface gravity (log g)2.77±0.21[6] cgs
Temperature4,788±49[5] K
Metallicity [Fe/H]−0.65±0.02[2] dex
Rotational velocity (v sin i)1.6[4] km/s
Age5.44[5] Gyr
Other designations
27 Ari, BD+17°380, FK5 1069, HD 15596, HIP 11698, HR 731, SAO 92983[7]
Database references
SIMBADdata

This appears to be a single-lined spectroscopic binary system with an orbital period of 130.7 days and an eccentricity of 0.366. It has an "a sin i" value of 10.00 ± 0.08 Gm (0.06685 ± 0.00053 AU), where a is the semimajor axis and i is the inclination to the line of sight from the Earth. This value provides a lower bound on the actual semimajor axis.[4] The visible component has a stellar classification of G8 III-IV Fe-2,[3] displaying mixed spectral traits of an evolved subgiant and a giant star, with a strong underabundance of iron. The CN bands of this star are very weak.[4]

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. 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.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. Griffin, R. F. (October 2011), "Spectroscopic binary orbits from photoelectric radial velocities - Paper 220: 60 Piscium, 27 Arietis, EZ Ursae Majoris, and 4 Equulei", The Observatory, 131 (5): 294–314, Bibcode:2011Obs...131..294G.
  5. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  6. Prugniel, P.; et al. (2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769.
  7. "27 Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-02.
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