astro.wikisort.org - Star
Tau4 Serpentis, Latinized from τ4 Serpentis, is a M-type bright giant star in the constellation of Serpens, approximately 520 light-years from the Earth.[1] It is classified as a semiregular late-type variable star, and its magnitude varies between +5.89 and +7.07 with a period of approximately 100 days.[2] τ4 is unique among the stars with the Bayer designation τ Serpentis as being the only one with no HR catalog number. Tau4 Serpentis has been found to display an inverse P Cygni profile,[4] where cold infalling gas on to the star creates redshifted hydrogen absorption lines next to the normal emission lines.[5]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Serpens |
| Right ascension | 15h 36m 28.1873s[1] |
| Declination | +15° 06′ 05.128″[1] |
| Apparent magnitude (V) | 5.89 to 7.07[2] |
| Characteristics | |
| Spectral type | M5II-III[1] |
| B−V color index | 1.2[1] |
| Variable type | SRB[2] |
| Astrometry | |
| Radial velocity (Rv) | −26 ± 5[1] km/s |
| Proper motion (μ) | RA: −3.41[1] mas/yr Dec.: 9.55[1] mas/yr |
| Parallax (π) | 6.27 ± 1.00 mas[1] |
| Distance | approx. 520 ly (approx. 160 pc) |
| Absolute magnitude (MV) | −0.03[3] |
| Details | |
| Luminosity | 155[3] L☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
References
- V* tau04 Ser -- Pulsating variable Star, database entry, SIMBAD. Accessed on line September 19, 2008.
- 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, Sternberg Astronomical Institute, Moscow, Russia. 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.
- 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.
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