HD 57682
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HD 57682 is a rare magnetic massive O-type main-sequence star star located in the constellation of Monoceros. It is one of only a small number of confirmed magnetic O-type stars and is notable for its strong dipolar magnetic field, which confines its stellar wind and produces observable spectroscopic variability.[8][9][10]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Monoceros[1] |
| Right ascension | 07h 22m 2.05s[2] |
| Declination | −08° 58′ 45.8″[2] |
| Apparent magnitude (V) | 6.42[1] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | O9.2IV[4] |
| Astrometry | |
| Radial velocity (Rv) | +24.1[5] km/s |
| Proper motion (μ) | RA: +9.659[2] mas/yr Dec.: +13.159[2] mas/yr |
| Parallax (π) | 0.8968±0.0739 mas[2] |
| Distance | 3,600 ± 300 ly (1,120 ± 90 pc) |
| Absolute magnitude (MV) | −4.4[3] |
| Details | |
| Mass | 17+19 −9[6] M☉ |
| Radius | 7.0+2.4 −1.8[6] R☉ |
| Luminosity | 79,433[3] L☉ |
| Surface gravity (log g) | 3.93[3] cgs |
| Temperature | 33,500[3] K |
| Rotation | ~63.5 days[3] |
| Rotational velocity (v sin i) | 10[3] km/s |
| Age | 4.5[3] Myr |
| Other designations | |
| MCW 529, HD 57682, HIP 35707, HR 2806, SAO 134580, TIC 187458882, TYC 5395-4693-1, IRAS 07196-0852, 2MASS J07220205-0858457[7] | |
| Database references | |
| SIMBAD | data |
Discovery and Observation
The magnetic field was first reported in 2009, making HD 57682 one of the few known magnetic O-type stars at the time (fewer than 10 confirmed). Follow-up studies in 2012) refined the rotational period, magnetic geometry, and magnetospheric properties. The star's sharp spectral lines and low rotation make it an ideal target for studying magnetism in massive stars.[6][11]
HD 57682 hosts a strong, organized dipolar magnetic field, discovered in 2009 as part of the Magnetism in Massive Stars (MiMeS) survey using spectropolarimetric observations with the ESPaDOnS instrument at the Canada-France-Hawaii Telescope. The surface polar strength of the dipole is estimated at approximately 880–1,680 G, with later refinements favoring lower values around 880 G and a high obliquity angle (~79°). It exhibits a weak stellar wind with a mass-loss rate of ~1.4×10−9 M☉/yr. The star is a runaway star, moving at high velocity away from its likely birthplace in the Canis Major OB1 association.[6][12][13]