78 Pegasi is a binary star system in the northern constellation of Pegasus. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.93.[2] The system is located approximately 224 light years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −8 km/s.[6] The double-star nature of this system was discovered by A. G. Clark in 1862. The components of this system orbit each other over a 630-year period with an eccentricity of 0.11.[10]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 23h 43m 59.48560s[1] |
| Declination | 29° 21′ 41.2342″[1] |
| Apparent magnitude (V) | 4.93[2] (5.07 / 8.10)[3] |
| Characteristics | |
| Spectral type | K0III[4] |
| U−B color index | +0.63[5] |
| B−V color index | +0.96[5] |
| Astrometry | |
| Radial velocity (Rv) | −8.33[6] km/s |
| Proper motion (μ) | RA: +71.10[1] mas/yr Dec.: -40.58[1] mas/yr |
| Parallax (π) | 14.54 ± 0.56 mas[1] |
| Distance | 224 ± 9 ly (69 ± 3 pc) |
| Absolute magnitude (MV) | 0.75[2] |
| Orbit[3] | |
| Period (P) | 630.15 yr |
| Semi-major axis (a) | 1.614″ |
| Eccentricity (e) | 0.112 |
| Inclination (i) | 60.64° |
| Longitude of the node (Ω) | 172.55° |
| Periastron epoch (T) | B 2247.71 |
| Argument of periastron (ω) (secondary) | 241.27° |
| Details | |
| 78 Peg A | |
| Mass | 1.50[7] M☉ |
| Radius | 10[7] R☉ |
| Luminosity | 57.35[2] L☉ |
| Surface gravity (log g) | 2.62[7] cgs |
| Temperature | 4,898[7] K |
| Metallicity [Fe/H] | +0.01[2] dex |
| Rotational velocity (v sin i) | 1.1[8] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary member, designated component A, is a magnitude 5.07[3] giant star with a stellar classification of K0III,[4] having exhausted the supply of hydrogen at its core and expanded to 10[7] times the Sun's radius. It is a red clump giant,[11] which indicates it is on the horizontal branch and is generating energy through core helium fusion. It has 1.5[7] times the mass of the Sun and is radiating 57[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,898 K.[7] The secondary companion, component B, is magnitude 8.10.[3]
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. Vizier catalog entry
- ^ a b c d e f 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. Vizier catalog entry
- ^ a b c d "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 1 August 2017. Retrieved 26 May 2017.
- ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
- ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
- ^ a b Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (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. S2CID 121883397.
- ^ a b c d e f g Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
- ^ De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series. 139 (3): 433. arXiv:astro-ph/0608248. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401. Vizier catalog entry
- ^ "78 Peg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-08-06.
- ^ Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical masses of a selected sample of orbital binaries". Astronomy & Astrophysics. 546: A69. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774. Vizier catalog entry
- ^ Tautvaišienė, G.; et al. (December 2010), "C, N and O abundances in red clump stars of the Milky Way", Monthly Notices of the Royal Astronomical Society, 409 (3): 1213–1219, arXiv:1007.4064, Bibcode:2010MNRAS.409.1213T, doi:10.1111/j.1365-2966.2010.17381.x, S2CID 119182458.