15 Sagittarii

15 Sagittarii is a blue-hued binary star[10] system in the southern zodiac constellation of Sagittarius. The estimated distance based upon photometry is around 4,200 ly (1,300 pc).[7] It is faintly visible to the naked eye with an apparent visual magnitude of 5.37.[2] The system is moving closer to the Sun with a heliocentric radial velocity of around −6 km/s.[6]

15 Sagittarii
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 15m 12.90641s[1]
Declination −20° 43′ 41.7738″[1]
Apparent magnitude (V) 5.37[2]
Characteristics
Spectral type O9.7 Iab[3] or B0 Iab[4]
B−V color index 0.007±0.004[5]
Astrometry
Radial velocity (Rv)−6.3±2.8[6] km/s
Proper motion (μ) RA: +1.60[1] mas/yr
Dec.: −1.51[1] mas/yr
Parallax (π)0.10 ± 0.45 mas[1]
Distance4,200±650[7] ly
(1,300±200 pc)
Details[8]
15 Sgr Aa
Mass~30[4] M☉
Radius28.6±12.5 R☉
Luminosity4.47+3.85
−2.07×105 L☉
Surface gravity (log g)3.10 cgs
Temperature28,000±1,000 K
Rotational velocity (v sin i)83±7[4] km/s
Other designations
15 Sgr, BD−20° 5054, HD 167264, HIP 89439, HR 6822, SAO 186543, WDS J18152-2044[9]
Database references
SIMBADdata

Chini et al. (2012) identify this as a double-lined spectroscopic binary star system.[10] It shows a stellar classification of O9.7 Iab,[3] matching a massive O-type supergiant star. Along with the O-type star 16 Sgr (HD 167263), it is ionizing an H II region along the western edge of the molecular cloud L291.[11]

The Washington Double Star Catalog lists four companions within a 2 arcsecond angular radius.[12]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. 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. Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J. (2014). "The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars". The Astrophysical Journal Supplement. 211 (1): 10. arXiv:1312.6222. Bibcode:2014ApJS..211...10S. doi:10.1088/0067-0049/211/1/10. S2CID 118847528.
  4. Fraser, M.; Dufton, P. L.; Hunter, I.; Ryans, R. S. I. (May 2010), "Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants", Monthly Notices of the Royal Astronomical Society, 404 (3): 1306−1320, arXiv:1001.3337, Bibcode:2010MNRAS.404.1306F, doi:10.1111/j.1365-2966.2010.16392.x, S2CID 118674151
  5. 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.
  6. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. Kemp, S. N.; et al. (December 1996), "Further optical and UV spectroscopy of stars in the direction of the Riegel & Crutcher cold cloud", Monthly Notices of the Royal Astronomical Society, 283 (3): 1089–1101, Bibcode:1996MNRAS.283.1089K, doi:10.1093/mnras/283.3.1089.
  8. Martins, F.; et al. (February 2015), "Radial dependence of line profile variability in seven O9-B0.5 stars", Astronomy & Astrophysics, 574: 38, arXiv:1409.5057, Bibcode:2015A&A...574A.142M, doi:10.1051/0004-6361/201423882, S2CID 118365203, A142.
  9. "15 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-15.
  10. Chini, R.; et al. (August 2012), "A spectroscopic survey on the multiplicity of high-mass stars", Monthly Notices of the Royal Astronomical Society, 424 (3): 1925–1929, arXiv:1205.5238, Bibcode:2012MNRAS.424.1925C, doi:10.1111/j.1365-2966.2012.21317.x, S2CID 119120749
  11. Marti, J.; et al. (October 1993), "HH 80-81: A Highly Collimated Herbig-Haro Complex Powered by a Massive Young Star", Astrophysical Journal, 416: 208, Bibcode:1993ApJ...416..208M, doi:10.1086/173227
  12. Sana, H.; et al. (November 2014), "Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection", The Astrophysical Journal Supplement Series, 215 (1): 35, arXiv:1409.6304, Bibcode:2014ApJS..215...15S, doi:10.1088/0067-0049/215/1/15, S2CID 53500788, 15.
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