70 Pegasi
70 Pegasi is a binary star[6] system in the northern constellation Pegasus. It is a faint star, visible to the naked eye under good seeing conditions, with an apparent visual magnitude of 4.56.[2] The measured annual parallax shift measured from Earth's orbit is 18.65 mas,[1] yielding a distance estimate of around 175 light years. The visual magnitude of the star is diminished by an extinction of 0.07±0.02 due to interstellar dust. It is moving closer to the Sun with a radial velocity of −17 km/s.[4]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 23h 29m 09.29698s[1] |
| Declination | +12° 45′ 37.9918″[1] |
| Apparent magnitude (V) | 4.56[2] |
| Characteristics | |
| Spectral type | G8 IIIa[3] |
| B−V color index | 0.940[2] |
| Astrometry | |
| Radial velocity (Rv) | −16.88±0.43[4] km/s |
| Proper motion (μ) | RA: +61.40[1] mas/yr Dec.: +24.82[1] mas/yr |
| Parallax (π) | 18.65 ± 0.78[1] mas |
| Distance | 175 ± 7 ly (54 ± 2 pc) |
| Absolute magnitude (MV) | 0.90[5] |
| Orbit[6] | |
| Period (P) | 941.03±0.12 d |
| Eccentricity (e) | 0.713±0.006 |
| Argument of periastron (ω) (secondary) | 57.0±1.2° |
| Semi-amplitude (K1) (primary) | 3.16±0.04 km/s |
| Details[4] | |
| 70 Peg A | |
| Mass | 2.49±0.06 M☉ |
| Radius | 8.44±0.37 R☉ |
| Luminosity | 47.9+4.6 −4.2 L☉ |
| Surface gravity (log g) | 2.92±0.05 cgs |
| Temperature | 5,032±15 K |
| Metallicity [Fe/H] | 0.05±0.03 dex |
| Rotational velocity (v sin i) | 3.6[7] km/s |
| Age | 590±40 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary with an orbital period of 2.58 years (941 days) and a high eccentricity of 0.713.[6] The visible component has a stellar classification of G8 IIIa,[3] indicating it is an evolved G-type giant star. It is a probable red clump star, which would mean it is generating energy through helium fusion at its core.[9] The star has 2.5 times the mass of the Sun and has expanded to more than 8 times the Sun's radius. It is radiating about 48 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,032 K.[4]
The secondary is most likely a low mass main sequence star with no more than 0.4 times the mass of the Sun.[6]
References
- 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.
- 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.
- 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.
- Maldonado, J.; et al. (June 2013), "The metallicity signature of evolved stars with planets", Astronomy & Astrophysics, 554: 18, arXiv:1303.3418, Bibcode:2013A&A...554A..84M, doi:10.1051/0004-6361/201321082, A84
- 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.
- Griffin, R. F. (August 2009), "Spectroscopic binary orbits from photoelectric radial velocities. Paper 207: 58 Piscium, 31 Vulpeculae, and 70 Pegasi", The Observatory, 129: 198−218, Bibcode:2009Obs...129..198G.
- 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.
- "70 Peg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-20.
- Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society, 408 (2): 1225−1232, arXiv:1006.3857, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x