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τ Serpentis

A visual band light curve for Tau Serpentis, plotted from ASAS-SN data
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Serpens
Right ascension	15 36 28.1827
Declination	+15° 06′ 05.240″
Apparent magnitude (V)	5.89 to 7.07
Characteristics
Spectral type	M5IIIa
B−V color index	1.2
Variable type	SRB
Astrometry
Radial velocity (Rv)	−26±5 km/s
Proper motion (μ)	RA: −3.623 mas/yr Dec.: +4.476 mas/yr
Parallax (π)	4.5628 ± 0.2728 mas
Distance	710 ± 40 ly (220 ± 10 pc)
Absolute magnitude (MV)	−0.03
Details
Mass	3.9 M☉
Radius	239 R☉
Luminosity	4,969 L☉
Surface gravity (log g)	−0.14 cgs
Temperature	3,178 K
Metallicity	+0.21 dex
Other designations
τ Ser, 17 Serpentis, BD+15° 2890, GC 20983, HD 139216, HIP 76423, SAO 101641, PPM 131543
Database references
SIMBAD	data

Tau Serpentis, Latinized from τ Serpentis, is a variable M-type giant star in the constellation of Serpens, approximately 710 light-years from the Earth. Its brightness varies from magnitude 5.89 to 7.07, making it occasionally bright enough to be faintly visible to the naked eye under very good observing conditions.

With a spectral classification M5IIIa, Tau Serpentis is a cool red giant star. The spectrum varies, and some sources classify it between M4IIIe and M6IIIe. Some of its spectral lines show an inverse P Cygni profile, where cold infalling gas on to the star creates redshifted hydrogen absorption lines next to the normal emission lines. Sometime between the years 1868 and 1877, John Ellard Gore discovered that the star's brightness varies. 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.

τ is unique among the stars with the Bayer designation τ Serpentis as being the only one with no HR catalog number.

References

1. "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.
2. ^ 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.
3. ^ 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.
4. ^ 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.
5. ^ V* tau04 Ser -- Pulsating variable Star, database entry, SIMBAD. Accessed on line September 19, 2008.
6. 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.
7. ^ 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.
8. ^ 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.
9. 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.
10. 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.
11. 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.
12. Toone, J. (June 2010). "British variable star associations, 1848-1908". Journal of the British Astronomical Association. 120 (3): 135–151. Bibcode:2010JBAA..120..135T. Retrieved 19 December 2024.

v t e Constellation of Serpens
List of stars in Serpens Serpens in Chinese astronomy
Stars	Bayer α (Unukalhai) β (Chow) γ (Ainalhai) δ ε ζ η θ (Alya) ι κ (Gudja) λ μ ν ξ ο π ρ σ τ τ τ τ τ τ τ τ υ φ χ ψ ω Flamsteed 3 4 5 6 7 8 10 11 (A) 14 16 25 (A) 29 36 (b) 39 40 43 45 46 47 59 (d) 60 (c) 61 64 3 Her Variable R W X RT UZ VV VY WX AA AN AO AP AR AU BQ CT CV CW EG FH FI FK FL FQ FR LV LW LX MR MS MT MV MY NN NO NQ NW OO OU PS QV QX QY V382 V411 HR 5665 5690 5692 5706 5711 5740 5745 5783 5796 5831 5850 5859 5861 5874 5909 5913 5931 5992 6005 6011 6014 6016 6449 6496 6544 6562 6568 6600 6620 6666 6681 6755 6756 6757 6785 6830 6840 6843 6858 6890 6898 6928 6993 (e) 6999 7008 7048 7076 7144 HD 135061 135615 136027 136118 138085 142245 143436 145936 146740 157969 168112 168443 168746 (Alasia) 175541 (Kaveh) Other ADS 9544 AS 296 9 11 22 23 27 Gliese 701 Gliese 710 GJ 1224 GX 17+2 IRAS 18418-0440 MWC 297 MWC 922 PG 1510+234 PG 1605+072 PSR B1534+11 PSR J1719−1438 Ross 508 Serpens FIRS 1 Serpens SVS 20 Serpens X-1 W40 IRS 1A South
Exoplanets CoRoT-9b CoRoT-11b CoRoT-22b CoRoT-23b CoRoT-27b HD 168746 b (Onasilos) HD 175541 b (Kavian) ω Serpentis b
Star clusters	NGC NGC 6535 NGC 6539 NGC 6604 NGC 6605 Other IC 4756 Messier 5 Messier 16 Serpens OB2 Serpens South Palomar 5
Nebulae	Other Abell 41 Eagle Nebula L134 L183 L483 Serpens cloud Sh2-54 Westerhout 40 Red Square Nebula S68
Galaxies	NGC 5887 5910 5911 5913 5919 5920 5921 5926 5928 5931 5936 5937 5940 5942 5941 5944 5951 5953 5954 5952 5956 5955 5957 5960 5962 5964 5970 5972 5975 5977 5980 5983 5984 5988 5991 5990 5994 5996 5997 6003 6004 6008 6006 6007 6009 6012 6010 6014 6020 6017 6018 6021 6022 6023 6027 6027a 6027b 6027c 6027d 6027e 6029 6033 6037 6036 6051 6063 6065 6066 6070 6080 6100 6118 6172 Other 317 318 321 323.1 324 326 Arp 72 Arp 220 4C 11.50 CGCG 049-033 Hoag's Object IC 4537 IC 4588 IRAS 15107+0724 NRAO 530 PDS 456 PG 1553+113 PGC 54493 PKS 1546+027
Galaxy clusters Abell 2040 Abell 2052 Abell 2063 Abell 2107 AWM 4 MKW 3s Seyfert's Sextet
Astronomical events GRB 970111 GRB 050813 GRB 060418 GRB 060526 SN 2004dk
Category

• Serpens
• Semiregular variable stars
• M-type giants
• Flamsteed objects
• Bayer objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Durchmusterung objects
• Asymptotic-giant-branch stars