Tau4 Serpentis, Latinized from τ4 Serpentis, is a variable M-type giant star in the constellation of Serpens, approximately 710 light-years from the Earth.[5]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Serpens |
| Right ascension | 15h 36m 28.1827s[2] |
| Declination | +15° 06′ 05.240″[2] |
| Apparent magnitude (V) | 5.89 to 7.07[3] |
| Characteristics | |
| Spectral type | M5IIIa[4] |
| B−V color index | 1.2[5] |
| Variable type | SRB[3] |
| Astrometry | |
| Radial velocity (Rv) | −26±5[5] km/s |
| Proper motion (μ) | RA: −3.623[2] mas/yr Dec.: +4.476[2] mas/yr |
| Parallax (π) | 4.5628 ± 0.2728 mas[2] |
| Distance | 710 ± 40 ly (220 ± 10 pc) |
| Absolute magnitude (MV) | −0.03[6] |
| Details | |
| Mass | 3.9[7] M☉ |
| Radius | 239[8] R☉ |
| Luminosity | 4,969[8] L☉ |
| Surface gravity (log g) | −0.14[7] cgs |
| Temperature | 3,178[7] K |
| Metallicity [Fe/H] | +0.21[7] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
With a spectral classification M5IIIa, Tau4 Serpentis is a cool red giant star. The spectrum varies,[4] and some sources classify it between M4IIIe and M6IIIe.[9] Some of its spectral lines show an inverse P Cygni profile,[10] where cold infalling gas on to the star creates redshifted hydrogen absorption lines next to the normal emission lines.[11] It is classified as a semiregular late-type variable, and its magnitude varies between +5.89 and +7.07 with a period of approximately 100 days.[3]
τ4 is unique among the stars with the Bayer designation τ Serpentis as being the only one with no HR catalog number.
References
edit- ^ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.
- ^ a b c d e 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 c tau 4 Ser, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars Archived 2017-06-20 at the Wayback Machine, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line September 19, 2008.
- ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373. S2CID 123149047.
- ^ a b c d V* tau04 Ser -- Pulsating variable Star, database entry, SIMBAD. Accessed on line September 19, 2008.
- ^ 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.
- ^ a b c d Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361.
- ^ a b McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. S2CID 73594365.
- ^ Skiff, B. A. (2014). "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)". VizieR On-line Data Catalog: B/Mk. Originally Published in: Lowell Observatory (October 2014). 1. Bibcode:2014yCat....1.2023S.
- ^ Kolotilov, E. A.; Russev, R. M. (January 1980). "Inverse P Cyg Profile of Halpha in the Spectrum of the Red Giant HD 139216 = tau4 Ser". Information Bulletin on Variable Stars. 1730: 1. Bibcode:1980IBVS.1730....1K.
- ^ Galactic Star and Planet Formation Research Group. "Lecture 7: The Collapse of Cores and Infall" (PDF). Department of Physics and Astronomy, University of Toledo. Retrieved 17 July 2015.