Theta Muscae
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Musca |
| Right ascension | 13h 08m 07.15286s |
| Declination | −65° 18′ 21.6819″ |
| Apparent magnitude (V) | 5.53 (5.662 + 7.555) |
| Characteristics | |
| θ Mus A | |
| Spectral type | WC5/6 + O6/7V + O9.5/B0Iab |
| U−B color index | −0.91 |
| B−V color index | −0.43 |
| Variable type | Eclipsing + WR |
| B | |
| Spectral type | O9III |
| U−B color index | −0.90 |
| B−V color index | −0.055 |
| Astrometry | |
| Radial velocity (Rv) | −28.4 km/s |
| Proper motion (μ) | RA: −2.10 mas/yr Dec.: −11.52 mas/yr |
| Parallax (π) | 0.26±0.48 mas |
| Distance | 7,400 ly (2,270 pc) |
| Absolute magnitude (MV) | −6.2 |
| Orbit | |
| Period (P) | 19.1375 d |
| Eccentricity (e) | 0.00 (assumed) |
| Inclination (i) | 49±6° |
| Semi-amplitude (K1) (primary) | 221±6 km/s |
| Details | |
| Aa | |
| Mass | <11.5 M☉ |
| Luminosity | 234,000 L☉ |
| Ab | |
| Mass | 44 M☉ |
| Luminosity | 295,000 L☉ |
| B | |
| Radius | 10.82+0.90 −0.50 R☉ |
| Surface gravity (log g) | 3.39+0.73 −0.33 cgs |
| Temperature | 20,213+970 −241 K |
| Metallicity [Fe/H] | 0.014±0.001 dex |
| Other designations | |
| Theta Muscae, CD−64°699, HR 4952, HD 113904, HIP 64094, GSC 08997-02337, SAO 252162, PPM 359890, GC 17788, UCAC3 50-186265, IRAS 13048−6502, WR 48 | |
| Database references | |
| SIMBAD | data |
Theta Muscae (θ Muscae) is a multiple star system in the southern constellation Musca ("the Fly"), containing a Wolf-Rayet star and two massive companions. With an apparent magnitude of 5.5, it is the second-brightest Wolf–Rayet star in the sky, although much of the visual brightness comes from the massive companions and it is not one of the closest of its type.