| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Monoceros |
| Right ascension | 06h 37m 24.04130s[1] |
| Declination | +06° 08′ 07.3719″[1] |
| Apparent magnitude (V) | 6.06[2] |
| Characteristics | |
| Spectral type | O8 III/I + O7.5 III[3] |
| U−B color index | –0.88[2] |
| B−V color index | +0.05[2] |
| Astrometry | |
| Radial velocity (Rv) | +24.5[4] km/s |
| Proper motion (μ) | RA: –2.73[1] mas/yr Dec.: +0.31[1] mas/yr |
| Distance | 5,245 ly (1,608[5] pc) |
| Details | |
| A | |
| Mass | 54[3] M☉ |
| Surface gravity (log g) | 3.5 ± 0.1[3] |
| Temperature | 33,500 ± 2000[3] K |
| Rotational velocity (v sin i) | 75[6] km/s |
| B | |
| Mass | 56[3] M☉ |
| Radius | 13.2 × 14.1[3] R☉ |
| Surface gravity (log g) | 3.5 ± 0.1[3] |
| Temperature | 33000 ± 2000[3] K |
| Rotational velocity (v sin i) | 300[6] km/s |
| Other designations | |
Plaskett's Star (HR 2422) is a spectroscopic binary at a distance of around 6600 light-years. It is one of the most massive binary stars known, with a total mass of about one hundred times that of the Sun. Indeed, it was long thought to be the most massive known binary system,[6] but since 2008 there is a body of opinion that Eta Carinae, which was previously thought to be a massive individual star, could be a binary system.
It is named after John Stanley Plaskett, the Canadian astronomer who discovered its binary nature in 1922. Plaskett was assisted in his observations by his son, Harry Hemley Plaskett. The star has a visual magnitude of 6.05, and is located in the constellation of Monoceros.
The orbital period for the pair is 14.39625 ± 0.00095 days.[3] The secondary is a rapid rotator with a projected rotational velocity of 300 km sec–1,[6] giving it a pronounced equatorial bulge.[3]
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