Location of θ Sagittarii (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19 59 44.17834 |
| Declination | −35° 16′ 34.7049″ |
| Apparent magnitude (V) | 4.37 |
| Characteristics | |
| Spectral type | B3 IVp |
| U−B color index | −0.67 |
| B−V color index | −0.15 |
| Astrometry | |
| Proper motion (μ) | RA: +5.60 mas/yr Dec.: −25.81 mas/yr |
| Parallax (π) | 6.29 ± 0.21 mas |
| Distance | 520 ± 20 ly (159 ± 5 pc) |
| Absolute magnitude (MV) | −1.63 |
| Orbit | |
| Period (P) | 2.1051 d |
| Eccentricity (e) | 0.00 |
| Periastron epoch (T) | 2411140.645 JD |
| Argument of periastron (ω) (secondary) | 0.00° |
| Semi-amplitude (K1) (primary) | 15.9 km/s |
| Details | |
| θ Sgr A | |
| Mass | 6.6±0.1 M☉ |
| Radius | 5.6 R☉ |
| Luminosity (bolometric) | 2,271 L☉ |
| Temperature | 17,900 K |
| Rotational velocity (v sin i) | 73 km/s |
| Age | 32.8±5.0 Myr |
| Other designations | |
| θ Sgr, CD−35° 13831, HD 189103, HIP 98412, HR 7623, SAO 211716, WDS J19597-3517 | |
| Database references | |
| SIMBAD | data |
Theta Sagittarii (θ Sagittarii) is a close binary star system in the zodiac constellation of Sagittarius. It is visible to the naked eye with an apparent visual magnitude of 4.37. Based upon an annual parallax shift of 6.29 mas as seen from Earth, this star is located around 520 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.24 due to interstellar dust.
This is a single-lined spectroscopic binary with an orbital period of just 2.1 days in a circular orbit. The visible member, component A, is a B-type subgiant star with a stellar classification of B3 IVp. It is around 33 million years old and is spinning with a projected rotational velocity of 73 km/s. The primary has 6.6 times the mass of the Sun and about 5.6 times the Sun's radius. It is radiating 2,271 times the solar luminosity from its photosphere at an effective temperature of 17,900 K.
References
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- ^ Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
- ^ Levato, H. (1975), "Rotational velocities and spectral types for a sample of binary systems", Astronomy and Astrophysics, 19: 91, Bibcode:1975A&AS...19...91L
- 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.
- ^ Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
- ^ Tetzlaff, N.; et al. (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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
- ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (2) (Third ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ Hohle, M. M.; et al. (2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.
- "tet01 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-07.
{{cite web}}: CS1 maint: postscript (link) - Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035, S2CID 119108982.
