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Star in the constellation Sagittarius From Wikipedia, the free encyclopedia
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]
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] |
Distance | 4,200±650[7] ly (1,300±200 pc) |
Details[8] | |
15 Sgr Aa | |
Mass | ~30[4] M☉ |
Radius | 28.6±12.5 R☉ |
Luminosity | 4.47+3.85 −2.07×105 L☉ |
Surface gravity (log g) | 3.10 cgs |
Temperature | 28,000±1,000 K |
Rotational velocity (v sin i) | 83±7[4] km/s |
Other designations | |
Database references | |
SIMBAD | data |
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]
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