HD 202951
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 21h 18m 52.02694s |
| Declination | +11° 12′ 12.1708″ |
| Apparent magnitude (V) | 5.97 |
| Characteristics | |
| Evolutionary stage | red giant branch |
| Spectral type | K5 III |
| B−V color index | 1.648 |
| Astrometry | |
| Radial velocity (Rv) | −37.3±2.5 km/s |
| Proper motion (μ) | RA: +21.643 mas/yr Dec.: +15.723 mas/yr |
| Parallax (π) | 3.3390±0.1317 mas |
| Distance | 980 ± 40 ly (300 ± 10 pc) |
| Absolute magnitude (MV) | −1.97 |
| Orbit | |
| 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 M☉ |
| Radius | 85 R☉ |
| Luminosity | 2,202 L☉ |
| Surface gravity (log g) | 1.29 cgs |
| Temperature | 3,805 K |
| Metallicity [Fe/H] | −0.26 dex |
| Rotational velocity (v sin i) | 4.4 km/s |
| Age | 10.7 Gyr |
| Other designations | |
| NSV 25543, BD+10°4516, FK5 3700, HD 202951, HIP 105224, HR 8149, SAO 107020 | |
| 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. The distance to this system can be estimated from the annual parallax shift of 3.34 mas, yielding a value of roughly 980 light years. It is moving closer with a heliocentric radial velocity of −37 km/s.
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.
The visible component is an evolved K-type giant star with a stellar classification of K5 III. 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. X-ray emission has been detected from this system.
References
- 1 2 3 4 5 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.
- 1 2 3 4 5 6 7 8 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.
- 1 2 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.
- 1 2 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.
- 1 2 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.
- 1 2 3 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.
- 1 2 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.
