Astronomy:Sigma Ophiuchi
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Short description: Star in the constellation Ophiuchus
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 26m 30.8806s[1] |
| Declination | 4° 08′ 25.2876″[1] |
| Apparent magnitude (V) | 4.31[2] (4.25 - 4.51[3]) |
| Characteristics | |
| Spectral type | K2 III[4] |
| U−B color index | +1.57[2] |
| B−V color index | +1.51[2] |
| Variable type | suspected[3] |
| Astrometry | |
| Radial velocity (Rv) | -27.81[5] km/s |
| Proper motion (μ) | RA: +1.459[6] mas/yr Dec.: +6.760[6] mas/yr |
| Parallax (π) | 3.7578 ± 0.1559[6] mas |
| Distance | 870 ± 40 ly (270 ± 10 pc) |
| Absolute magnitude (MV) | -2.85[7] |
| Details | |
| Mass | 4.87[8] M☉ |
| Radius | 94[9] R☉ |
| Luminosity | 1,995 - 2,032[9] L☉ |
| Surface gravity (log g) | 1.52[10] cgs |
| Temperature | 3,986±170[9] K |
| Metallicity [Fe/H] | -0.07[8] dex |
| Rotational velocity (v sin i) | 4.2[11] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Sigma Ophiuchi, Latinized from σ Ophiuchi, is a single,[12] orange-hued star in the equatorial constellation Ophiuchus. Its apparent visual magnitude is 4.31,[2] which is bright enough to be faintly visible to the naked eye. The annual parallax shift of 3.62 mas as seen from Earth provides a distance estimate of roughly 900 light years. It is moving closer to the Sun with a radial velocity of −28 km/s.[5]
This is an evolved giant star of type K with a stellar classification of K2 III.[4] Wittkowski et al. (2017) consider it to have a luminosity class of II-III, suggesting it is in a transitional zone between giants and supergiant stars.[13] It has around 5 times the mass of the Sun and 73 times the Sun's radius. The star is radiating 2,047 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,540 K.[8]
References
- ↑ 1.0 1.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237. Bibcode: 2002yCat.2237....0D.
- ↑ 3.0 3.1 Samus, N. N. et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S 1. Bibcode: 2009yCat....102025S.
- ↑ 4.0 4.1 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey 05: 0. Bibcode: 1999MSS...C05....0H.
- ↑ 5.0 5.1 Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data". Astronomy & Astrophysics 430: 165–186. doi:10.1051/0004-6361:20041272. Bibcode: 2005A&A...430..165F.
- ↑ 6.0 6.1 6.2 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. Vizier catalog entry
- ↑ 8.0 8.1 8.2 Reffert, Sabine; Bergmann, Christoph; Quirrenbach, Andreas; Trifonov, Trifon; Künstler, Andreas (2015). "Precise radial velocities of giant stars". Astronomy & Astrophysics 574: A116. doi:10.1051/0004-6361/201322360. Bibcode: 2015A&A...574A.116R. Vizier catalog entry
- ↑ 9.0 9.1 9.2 Messineo, M.; Brown, A. G. A. (2019). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal 158 (1): 20. doi:10.3847/1538-3881/ab1cbd. Bibcode: 2019AJ....158...20M.
- ↑ Hekker, S.; Meléndez, J. (2007). "Precise radial velocities of giant stars". Astronomy and Astrophysics 475 (3): 1003. doi:10.1051/0004-6361:20078233. Bibcode: 2007A&A...475.1003H.
- ↑ De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series 139 (3): 433. doi:10.1051/aas:1999401. Bibcode: 1999A&AS..139..433D. Vizier catalog entry
- ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Wittkowski, M. et al. (January 2017), "VLTI/AMBER spectro-interferometry of the late-type supergiants V766 Cen (=HR 5171 A), σ Oph, BM Sco, and HD 206859", Astronomy & Astrophysics 597: 16, doi:10.1051/0004-6361/201629349, A9, Bibcode: 2017A&A...597A...9W.
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