HR 7955

HR 7955 is a binary star[2] system in the northern circumpolar constellation of Cepheus, near the constellation border with Cygnus. It has a yellow-white hue and is faintly visible to the naked eye with a combined apparent visual magnitude of 4.51.[2] The system is located at a distance of 89 light-years (27.3 parsecs) from the Sun, based on parallax.[1] It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.243 arc seconds per annum,[8] and is drifting closer to the Sun with a radial velocity of -33 km/s.[3]

HR 7955
Observation data
Epoch J2000      Equinox J2000
Constellation Cepheus
Right ascension 20h 45m 21.12879s[1]
Declination +57° 34′ 47.0080″[1]
Apparent magnitude (V) 4.51[2]
Characteristics
Spectral type F8IV-V + F9IV-V[2]
Astrometry
Radial velocity (Rv)−32.82±0.04[3] km/s
Proper motion (μ) RA: −62.32[1] mas/yr
Dec.: −236.00[1] mas/yr
Parallax (π)36.64 ± 0.48 mas[1]
Distance89 ± 1 ly
(27.3 ± 0.4 pc)
Absolute magnitude (MV)2.35[4]
Orbit[2]
Period (P)494.16±0.58 d
Semi-major axis (a)0.065±0.001"
(≥50.2±0.5 Gm[5])
Eccentricity (e)0.551±0.004
Inclination (i)24.53±3.13°
Longitude of the node (Ω)325.21±1.05°
Periastron epoch (T)B 1996.335 ± 0.0017
Argument of periastron (ω)
(secondary)		68.86±0.76°
Details[2]
HR 7955 A
Mass1.071±0.037 M☉
Age2.25[6] Gyr
HR 7955 B
Mass1.047±0.037 M☉
Other designations
BD+57°2240, FK5 782, GJ 9706, HD 198084, HIP 102431, HR 7955, SAO 32862[7]
Database references
SIMBADdata

The double-lined nature of this spectroscopic binary system was not announced until 1972.[5] It has an orbital period of 1.35 years and an eccentricity of 0.551.[2] Both components appear to be slightly evolved stars that are leaving the main sequence and becoming subgiant stars, with stellar classifications of F8IV-V and F9IV-V. They each have slightly greater mass than the Sun: 107% and 105%, respectively.[2] The system is about 2.25 billion years old.[6]

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. S2CID 18759600.
  2. Farrington, C. D.; et al. (2010). "Separated Fringe Packet Observations with the CHARA Array. I. Methods and New Orbits for χ Draconis, HD 184467, and HD 198084". The Astronomical Journal. 139 (6): 2308. Bibcode:2010AJ....139.2308F. doi:10.1088/0004-6256/139/6/2308.
  3. Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
  4. Griffin, R. F.; Suchkov, A. A. (July 2003). "The Nature of Overluminous F Stars Observed in a Radial-Velocity Survey". The Astrophysical Journal Supplement Series. 147 (1): 103–144. Bibcode:2003ApJS..147..103G. doi:10.1086/367855.
  5. Griffin, R. F. (October 1999), "Spectroscopic binary orbits from photoelectric radial velocities. Paper 148: HR 7955", The Observatory, 119: 272–283, Bibcode:1999Obs...119..272G
  6. Luck, R. Earle (January 2017), "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants", The Astronomical Journal, 153 (1): 19, arXiv:1611.02897, Bibcode:2017AJ....153...21L, doi:10.3847/1538-3881/153/1/21, S2CID 119511744, 21.
  7. "HD 198084". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 6 September 2012.
  8. Lépine, Sébastien; Shara, Michael M. (March 2005). "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)". The Astronomical Journal. 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854. S2CID 2603568.
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