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OP Andromedae 
Summary
OP Andromedae is a variable star in the constellation Andromeda. Varying between magnitudes 6.27 and 6.41 over 2.36 days, it has been classified as an RS Canum Venaticorum variable, but there has not been any proof of binarity, yet.[3] It is a red giant star with a spectral classification of K1III.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 01h 36m 27.1998s[2] |
| Declination | +48° 43′ 21.9998″}[2] |
| Apparent magnitude (V) | 6.27 - 6.41[3] |
| Characteristics | |
| Spectral type | K1III[3] |
| Apparent magnitude (J) | 3.794[4] |
| Apparent magnitude (H) | 3.165[4] |
| Apparent magnitude (K) | 2.914[4] |
| B−V color index | 1.2478[5] |
| Variable type | RS CVn[3] |
| Astrometry | |
| Radial velocity (Rv) | −42.12±0.14[2] km/s |
| Proper motion (μ) | RA: −15.189±0.153[2] mas/yr Dec.: −17.663±0.148[2] mas/yr |
| Parallax (π) | 6.3462 ± 0.0912 mas[2] |
| Distance | 514 ± 7 ly (158 ± 2 pc) |
| Absolute magnitude (MV) | 0.37 ± 0.23[6] |
| Details | |
| Mass | 1.5 – 3[7] M☉ |
| Radius | 16.1±2.2[6] R☉ |
| Luminosity | 128.825[7] L☉ |
| Surface gravity (log g) | 2.14[7] cgs |
| Temperature | 4,490[7] K |
| Metallicity [Fe/H] | -0.10[7] dex |
| Rotational velocity (v sin i) | 7.2[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
OP Andromedae is one of the few red giant stars where it was detected an overabundance of 7Li.[6] The mechanism that enhances lithium in red giants is still unknown. It was proposed that those stars engulfed planets in the recent past; however, this theory was discarded since there is an overabundance of just one lithium isotope.[7]
References edit
- ^ Barksdale, W. S.; Boyd, L. J.; Genet, R. M.; Chang, S.; Hall, D. S.; Ingvarsson, S. I. (1984). "Discovery that HR 454 is a Variable Star". Information Bulletin on Variable Stars. 2632.
- ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d N. N. Samus; O. V. Durlevich; et al. "OP And database entry". Combined General Catalog of Variable Stars (2017 ed.). CDS. Retrieved 2018-11-12.
- ^ a b c Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
- ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy & Astrophysics, 355: L27–L30, Bibcode:2000A&A...355L..27H.
- ^ a b c Balachandran, Suchitra C.; Fekel, Francis C.; Henry, Gregory W.; Uitenbroek, Han (2000). "Two K Giants with Supermeteoritic Lithium Abundances: HDE 233517 and HD 9746". The Astrophysical Journal. 542 (2): 978–88. Bibcode:2000ApJ...542..978B. CiteSeerX 10.1.1.36.1062. doi:10.1086/317055. S2CID 15952468.
- ^ a b c d e f g Takeda, Y.; Tajitsu, A. (August 2017). "On the observational characteristics of lithium-enhanced giant stars in comparison with normal red giants". Publications of the Astronomical Society of Japan. 69 (4): 978–88. arXiv:1706.02273. Bibcode:2017PASJ...69...74T. doi:10.1093/pasj/psx057. S2CID 119451146.