15 Sagittarii
15 Sagittarii is a blue-hued binary star system in the southern zodiac constellation of Sagittarius. The estimated distance based upon  photometry is around . It is faintly visible to the naked eye with an apparent visual magnitude of 5.37. The system is moving closer to the Sun with a heliocentric radial velocity of around −6 km/s. Chini et al. (2012) identify this as a double-lined spectroscopic binary star system. It shows a stellar classification of O9.7 Iab, 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. The Washington Double Star Catalog lists four companions within a 2 arcsecond angular radius. References

O-type supergiants
Spectroscopic binaries
Sagittarius (constellation)
Durchmusterung objects
Sagittarii, 15
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