85 Pegasi
85 Pegasi is a multiple star system 39.5 light years away[2] in the constellation of Pegasus. The primary component is sixth magnitude 85 Pegasi A, which is a yellow dwarf like the Sun. The secondary component, 85 Pegasi B, is a ninth magnitude orange dwarf that takes 26.28 years to orbit at 10.3 AU around the primary in an elliptical orbit. The orbital distance ranges from 6.4 AU at periastron to 14.2 AU at apastron. 85 Pegasi B may itself be a binary, with a close, faint red dwarf companion (designated 85 Pegasi Bb) separated by 2 AU from the primary (designated 85 Pegasi Ba). The mass would be 11% solar mass (M☉). All components in the star system including Star A are smaller, cooler and less massive, luminous, and metallic than the Sun and 51 Pegasi.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 00h 02m 10.16s[1] |
| Declination | +27° 04′ 56.1″[1] |
| Apparent magnitude (V) | 5.75 / 8.89 |
| Characteristics | |
| Spectral type | G5Vb / K7V |
| Apparent magnitude (B) | 6.42 / 11.0 |
| Apparent magnitude (R) | 5.38 |
| Apparent magnitude (I) | 4.96 |
| Apparent magnitude (J) | 4.702 |
| Apparent magnitude (H) | 4.179 |
| Apparent magnitude (K) | 4.068 |
| U−B color index | 0.05 / ? |
| B−V color index | 0.67 / ? |
| V−R color index | 0.37 / ? |
| R−I color index | 0.42 / ? |
| Variable type | None |
| Astrometry | |
| Radial velocity (Rv) | -36.2 km/s |
| Proper motion (μ) | RA: 780.22 ± 2.01[1] mas/yr Dec.: -917.75 ± 1.20[1] mas/yr |
| Parallax (π) | 82.5 ± 0.8[2] mas |
| Distance | 39.5 ± 0.4 ly (12.1 ± 0.1 pc) |
| Absolute magnitude (MV) | 5.32[3] |
| Orbit | |
| Companion | 85 Pegasi B |
| Period (P) | 26.28 yr |
| Semi-major axis (a) | 0.83″ |
| Eccentricity (e) | 0.38 |
| Inclination (i) | 49° |
| Details | |
| Mass | 0.88 / 0.55 M☉ |
| Radius | 0.91 / 0.67 R☉ |
| Luminosity | 0.61 / 0.05 L☉ |
| Surface gravity (log g) | 4.45 / 4.58 cgs |
| Temperature | 5550 / 4200 K |
| Metallicity | 58–75% |
| Age | 3.8–4.4[4] Gyr |
| Other designations | |
| 85 Pegasi A: ADS 17175 A, GJ 914 A, BD +26°4734 A, BU 733 A. | |
| 85 Pegasi B: ADS 17175 B, GJ 914 B, BD +26°4734 B, BU 733 B. | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
An infrared excess has been detected around the primary, most likely indicating the presence of a circumstellar disk at a radius of more than 97 AU. The temperature of this dust is below 25 K.[5]
References
- van Leeuwen, F. (November 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. Vizier catalog entry
- Söderhjelm, S. (January 1999). "Visual binary orbits and masses POST HIPPARCOS". Astronomy and Astrophysics. 341: 121–140. Bibcode:1999A&A...341..121S. Vizier catalog entry
- Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
- Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785.
- Eiroa, C.; et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics. 555: A11. arXiv:1305.0155. Bibcode:2013A&A...555A..11E. doi:10.1051/0004-6361/201321050.
- J. Fernandes; P. Morel; Y. Lebreton (September 2002). "A calibration of the 85 Peg binary system". Astronomy and Astrophysics. 392 (2): 529–533. Bibcode:2002A&A...392..529F. doi:10.1051/0004-6361:20020962. Retrieved 2007-06-06.