HD 151932
 Location of WR 78 (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Scorpius |
| Right ascension | 16h 52m 19.24769s |
| Declination | −41° 51′ 16.2631″ |
| Apparent magnitude (V) | 6.45 - 6.61 |
| Characteristics | |
| Spectral type | WN7h |
| U−B color index | -0.63 |
| B−V color index | +0.27 |
| Variable type | WR |
| Astrometry | |
| Radial velocity (Rv) | -25.00 km/s |
| Proper motion (μ) |
RA: -1.98 mas/yr Dec.: -1.76 mas/yr |
| Parallax (π) | 0.54 ± 0.55mas |
| Distance | 6,490 ly (1,990pc) |
| Absolute magnitude (MV) | –6.82 |
| Details | |
| Mass | 44 M☉ |
| Radius | 16.7 R☉ |
| Luminosity (bolometric) | 1600000 L☉ |
| Surface gravity (log g) | 3.5 cgs |
| Temperature | 50100 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 151932, also known as WR 78, is a Wolf-Rayet star located in the constellation Scorpius, close to the galactic plane. Its distance is not well known; it may be anywhere between 1,580 and 2,000 light years (5,150 to 6,500 parsecs) away from the Earth. Despite being a blue-colored Wolf-Rayet star, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands. HD 151932 lies about 22′ west of the open cluster NGC 6231, the center of the OB association Scorpius OB1; it is not clear whether it is a part of the association or not. With an apparent magnitude of about 6.5, it is one of the few Wolf-Rayet stars that can be seen with the naked eye (although it can only be seen with the naked eye under excellent viewing conditions).
HD 151932 is one of the most luminous stars known at 1,600,000 L☉. Like most extremely massive stars, HD 151932 is losing mass via its stellar wind. The total rate of mass loss is 5×10−5 M☉/yr. The multiplicity (i.e., whether the star is a single star or a binary star system) of HD 151932 has not been studied very much. A periodic shift in the spectrum with a period of 3.3 days (implying it is a spectroscopic binary) has been noticed, but it may be spurious; the star appears to be a single star but may be orbiting face-on and/or with a lower-mass companion.
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