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]
| 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] |
| Distance | 89 ± 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 | |
| Mass | 1.071±0.037 M☉ |
| Age | 2.25[6] Gyr |
| HR 7955 B | |
| Mass | 1.047±0.037 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
edit- ^ a b c d e f 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.
- ^ a b c d e f g h 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. S2CID 122357261.
- ^ a b 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.
- ^ 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.
- ^ a b 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
- ^ a b 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.
- ^ "HD 198084". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 6 September 2012.
- ^ 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.