AB7
Binary star in the Small Magellanic Cloud in the constellation Tucana / From Wikipedia, the free encyclopedia
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AB7, also known as SMC WR7, is a binary star in the Small Magellanic Cloud. A Wolf–Rayet star and a supergiant companion of spectral type O orbit in a period of 19.56 days. The system is surrounded by a ring-shaped nebula known as a bubble nebula.
Quick Facts Constellation, Right ascension ...
AB7 is the brightest white star at the centre of the cavity within the nebula, not the brighter reddish star.[1] False colour image: red is HI; green is OIII; blue is HeIII. | |
Observation data Epoch J2000.0 Equinox J2000.0 | |
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Constellation | Tucana |
Right ascension | 01h 03m 35.93s[2] |
Declination | −72° 03′ 22.0″[2] |
Apparent magnitude (V) | 13.016[2] |
Characteristics | |
Spectral type | WN4 + O6I(f)[2] |
U−B color index | −1.021[2] |
B−V color index | −0.062[2] |
Astrometry | |
Radial velocity (Rv) | 172[3] km/s |
Distance | 197,000 ly (61,000 pc) |
Absolute magnitude (MV) | −6.1[3] (−4.4 + −5.7[4]) |
Orbit[3] | |
Period (P) | 19.560±0.0005 d |
Eccentricity (e) | 0.07±0.02 |
Inclination (i) | 68+22 −15[4]° |
Periastron epoch (T) | 2,451,549.2±0.8 |
Argument of periastron (ω) (primary) | 101±16° |
Semi-amplitude (K1) (primary) | 196±4 km/s |
Semi-amplitude (K2) (secondary) | 101±2 km/s |
Details[4] | |
WR | |
Mass | 23 M☉ |
Radius | 3.4 R☉ |
Luminosity | 1,259,000 L☉ |
Surface gravity (log g) | 4.7 cgs |
Temperature | 105,000 K |
O | |
Mass | 44 M☉ |
Radius | 14 R☉ |
Luminosity | 316,000 L☉ |
Surface gravity (log g) | 3.6 cgs |
Temperature | 36,000 K |
Rotational velocity (v sin i) | 150 km/s |
Age | 3.4 Myr |
Other designations | |
Database references | |
SIMBAD | data |
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