| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 06h 26m 19.155s[1] |
| Declination | +07° 58′ 28.06″[1] |
| Apparent magnitude (V) | 9.88[2] |
| Characteristics | |
| Spectral type | qWR + B7V[3] |
| U−B color index | −0.76[4] |
| B−V color index | −0.07[4] |
| Variable type | suspected |
| Astrometry | |
| Proper motion (μ) | RA: −0.389[1] mas/yr Dec.: −0.339[1] mas/yr |
| Parallax (π) | 0.9955 ± 0.0346 mas[1] |
| Distance | 991[3] pc |
| Orbit[3] | |
| Period (P) | 8,200 days |
| Semi-major axis (a) | 10.5 AU |
| Eccentricity (e) | 0.46 |
| Inclination (i) | 49±11° |
| Argument of periastron (ω) (secondary) | 132±11° |
| Semi-amplitude (K1) (primary) | 5.8±1.3 (B-type star) km/s |
| Details[3] | |
| qWR | |
| Mass | 2.03±0.44 M☉ |
| Radius | 0.88±0.11 R☉ |
| Luminosity | 6760±830 L☉ |
| Temperature | 56000±6000 K |
| Rotation | 124.82±0.21 days |
| Age | 105 Myr |
| B7V | |
| Mass | 3.40±0.06 M☉ |
| Radius | 2.63±0.41 R☉ |
| Luminosity | 178±22 L☉ |
| Temperature | 13000±500 K |
| Age | 105 Myr |
| Other designations | |
TYC 732-754-1, ALS 8946, BD+08 1332, 2MASS J06261915+0758280 | |
| Database references | |
| SIMBAD | data |
HD 45166 is a binary consisting of a so-called quasi Wolf–Rayet (qWR) star and a B-type main-sequence star, near the cluster NGC 2244, in the constellation of Monoceros.[5] A quasi Wolf–Rayet star is a star with a spectrum resembling those of true Wolf–Rayet stars, but being less massive and luminous than a true Wolf–Rayet star. The primary of HD 45166 is currently the only known example of a qWR star.
In 2023, the primary of HD 45166 was also found to be extremely magnetic, the most magnetic massive star known. It is currently the only Wolf-Rayet star in which a significant magnetic field was measured. It has a magnetic field strength of up to 43 kG, or about 43,000 times the Sun's magnetic field strength. This means that it is likely that when it dies in a type Ib/IIb supernova, the remnant will be a magnetar.[3]
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