Astronomy:Tau Librae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Libra |
| Right ascension | 15h 38m 39.36950s[1] |
| Declination | −29° 46′ 39.8956″[1] |
| Apparent magnitude (V) | 3.68[2] |
| Characteristics | |
| Spectral type | B2.5 V[3] |
| U−B color index | −0.717[2] |
| B−V color index | −0.179[2] |
| Astrometry | |
| Radial velocity (Rv) | +33.3±2.3[4] km/s |
| Proper motion (μ) | RA: −22.08[1] mas/yr Dec.: −24.46[1] mas/yr |
| Parallax (π) | 8.89 ± 0.20[1] mas |
| Distance | 367 ± 8 ly (112 ± 3 pc) |
| Absolute magnitude (MV) | −1.59[5] |
| Orbit[6] | |
| Period (P) | 3.2907 d |
| Eccentricity (e) | 0.28 |
| Longitude of the node (Ω) | 114° |
| Periastron epoch (T) | 2439272.312 JD |
| Semi-amplitude (K1) (primary) | 75 km/s |
| Semi-amplitude (K2) (secondary) | 167 km/s |
| Details | |
| τ Lib A | |
| Mass | 7.25±0.49[7] M☉ |
| Radius | 3.2[8] R☉ |
| Luminosity (bolometric) | 2,705[7] L☉ |
| Surface gravity (log g) | 4.33[9] cgs |
| Temperature | 17,990[9] K |
| Metallicity [Fe/H] | +0.17[9] dex |
| Rotational velocity (v sin i) | 134[4] km/s |
| Age | 31.5±5.6[10] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Tau Librae, Latinized from τ Librae, is the Bayer designation for a binary star system at the southern edge of the zodiac constellation of Libra. It can be seen with the naked eye, having an apparent visual magnitude of 3.68.[2] The distance to this system is around 367 light years, as determined from an annual parallax shift of 8.89 mas.[1]
Judging by its motion through space and physical properties, this system is a member of the Upper Centaurus–Lupus group of the Scorpius–Centaurus association.[4] It is double-lined[12] spectroscopic binary with an orbital period of just 3.3 days and an eccentricity of 0.28.[6] The primary, component A, is a B-type main sequence star with a stellar classification of B2.5 V.[3] It is estimated to hold more than seven[7] times the mass of the Sun and have over three[8] times the Sun's radius. It is only 31.5[10] million years old and is spinning relatively rapidly with a projected rotational velocity of 134 km/s.[4] It is a heartbeat star system, with pulsations caused by tidal forces.[13]
The system is emitting an infrared excess, suggesting the presence of a circumstellar disk of material.[9]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement 15: 459, doi:10.1086/190168, Bibcode: 1968ApJS...15..459G.
- ↑ 3.0 3.1 Hiltner, W. A.; Garrison, R. F.; Schild, R. E. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal 157: 313–326, doi:10.1086/150069, Bibcode: 1969ApJ...157..313H.
- ↑ 4.0 4.1 4.2 4.3 Jilinski, E. et al. (March 2006), "Radial velocity measurements of B stars in the Scorpius–Centaurus association", Astronomy and Astrophysics 448 (3): 1001–1006, doi:10.1051/0004-6361:20041614, Bibcode: 2006A&A...448.1001J.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Pourbaix, D. et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics 424 (2): 727–732, doi:10.1051/0004-6361:20041213, Bibcode: 2004A&A...424..727P.
- ↑ 7.0 7.1 7.2 Hohle, M. M. et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, doi:10.1002/asna.200911355, Bibcode: 2010AN....331..349H.
- ↑ 8.0 8.1 Pasinetti-Fracassini, L. E. et al. (February 2001), "Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics 367: 521–524, doi:10.1051/0004-6361:20000451, Bibcode: 2001A&A...367..521P.
- ↑ 9.0 9.1 9.2 9.3 Saffe, C.; Gómez, M.; Pintado, O.; González, E. (October 2008), "Spectroscopic metallicities of Vega-like stars", Astronomy and Astrophysics 490 (1): 297–305, doi:10.1051/0004-6361:200810260, Bibcode: 2008A&A...490..297S.
- ↑ 10.0 10.1 Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, doi:10.1111/j.1365-2966.2010.17434.x, Bibcode: 2011MNRAS.410..190T.
- ↑ "tau Lib". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tau+Lib.
- ↑ Strom, Stephen E. et al. (February 2005), "B Star Rotational Velocities in h and χ Persei: A Probe of Initial Conditions during the Star Formation Epoch?", The Astronomical Journal 129 (2): 809–828, doi:10.1086/426748, Bibcode: 2005AJ....129..809S.
- ↑ Sharma, Awshesh N.; Bedding, Timothy R.; Saio, Hideyuki; White, Timothy R. (2022). "Pulsating B stars in the Scorpius–Centaurus Association with TESS". Monthly Notices of the Royal Astronomical Society 515 (1): 828–840. doi:10.1093/mnras/stac1816. Bibcode: 2022MNRAS.515..828S.
External links
- Kaler, James B. (May 17, 2013), "Tau Librae", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/taulib.html, retrieved 2017-02-02.
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