HD 202951
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Equuleus[1] |
| Right ascension | 21h 18m 52.02694s[2] |
| Declination | +11° 12′ 12.1708″[2] |
| Apparent magnitude (V) | 5.97[1] |
| Characteristics | |
| Evolutionary stage | red giant branch[2] |
| Spectral type | K5 III[1] |
| B−V color index | 1.648[3] |
| Astrometry | |
| Radial velocity (Rv) | −37.3±2.5[4] km/s |
| Proper motion (μ) | RA: +21.643[2] mas/yr Dec.: +15.723[2] mas/yr |
| Parallax (π) | 3.3390±0.1317 mas[2] |
| Distance | 980 ± 40 ly (300 ± 10 pc) |
| Absolute magnitude (MV) | −1.97[3] |
| Orbit[5] | |
| Period (P) | 999.8±2.4 d |
| Eccentricity (e) | 0.229±0.018 |
| Periastron epoch (T) | 53771±12 MJD |
| Argument of periastron (ω) (secondary) | 3±5° |
| Semi-amplitude (K1) (primary) | 4.09±0.08 km/s |
| Details | |
| Mass | 1.15[6] M☉ |
| Radius | 85[7] R☉ |
| Luminosity | 2,202[2] L☉ |
| Surface gravity (log g) | 1.29[6] cgs |
| Temperature | 3,805[8] K |
| Metallicity [Fe/H] | −0.26[6] dex |
| Rotational velocity (v sin i) | 4.4[9] km/s |
| Age | 10.7[8] Gyr |
| Other designations | |
| NSV 25543, BD+10°4516, FK5 3700, HD 202951, HIP 105224, HR 8149, SAO 107020[10] | |
| Database references | |
| SIMBAD | data |
HD 202951 is a probable binary star system located in the northern constellation of Equuleus. It is near the lower limit of visibility to the naked eye, having an apparent visual magnitude of 5.97.[1] The distance to this system can be estimated from the annual parallax shift of 3.34 mas,[2] yielding a value of roughly 980 light years. It is moving closer with a heliocentric radial velocity of −37 km/s.[4]
Griffin (2012) found this to be a single-lined spectroscopic binary system with an orbital period of 2.7373 ± 0.0066 yr and an eccentricity of 0.23. The a sin i value for the primary component is 54.8 ± 1.1 Gm (0.366 ± 0.007 AU), where a is the semimajor axis and i is the (unknown) orbital inclination. This value provides a lower bound for the actual semimajor axis.[5]
The visible component is an evolved K-type giant star with a stellar classification of K5 III.[1] It is a candidate variable star of unknown type, showing an amplitude variation of 0.0115 magnitude with a frequency of 0.47645 times per day, or one cycle per 2.1 days.[11] X-ray emission has been detected from this system.[12]
References
- ^ a b c d e 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. XHIP record for this object at VizieR.
- ^ a b c d e f g h Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b Ryon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific, 121 (882): 842, arXiv:0907.3346, Bibcode:2009PASP..121..842R, doi:10.1086/605456, S2CID 17821279.
- ^ a b Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
- ^ a b Griffin, R. F. (February 2012), "Spectroscopic binary orbits from photoelectric radial velocities - Paper 222: HR 4241, HR 7208, HR 8026, and HR 8149", The Observatory, 132 (1): 16–33, Bibcode:2012Obs...132...16G.
- ^ a b c Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G.; Valentini, M.; Torralba Elipe, G.; Steinmetz, M.; Pantaleoni-González, M.; Malhotra, S.; Jiménez-Arranz, Ó.; Enke, H.; Casamiquela, L.; Ardèvol, J. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics. 691: A98. arXiv:2407.06963. Bibcode:2024A&A...691A..98K. doi:10.1051/0004-6361/202451427.
- ^ Stassun, Keivan G.; et al. (2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467.
- ^ a b Kordopatis, G.; Schultheis, M.; McMillan, P. J.; Palicio, P. A.; De Laverny, P.; Recio-Blanco, A.; Creevey, O.; Álvarez, M. A.; Andrae, R.; Poggio, E.; Spitoni, E.; Contursi, G.; Zhao, H.; Oreshina-Slezak, I.; Ordenovic, C.; Bijaoui, A. (2023). "Stellar ages, masses, extinctions, and orbital parameters based on spectroscopic parameters of Gaia DR3". Astronomy and Astrophysics. 669: A104. arXiv:2206.07937. Bibcode:2023A&A...669A.104K. doi:10.1051/0004-6361/202244283.
- ^ De Medeiros, J. R.; et al. (October 2002), "The Rotation of Binary Systems with Evolved Components", The Astrophysical Journal, 578 (2): 943–950, arXiv:astro-ph/0207288, Bibcode:2002ApJ...578..943D, doi:10.1086/342613, S2CID 16196039.
- ^ "HD 202951". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-20.
- ^ Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331 (1): 45–59, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x, S2CID 10505995.
- ^ Smith, Graeme H.; Shetrone, Matthew D. (2000), "CaII K Emission-Line Asymmetry among Red Giants Detected by the ROSAT Satellite", The Publications of the Astronomical Society of the Pacific, 112 (776): 1320, Bibcode:2000PASP..112.1320S, doi:10.1086/316634.