BI 253
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 05h 37m 34.461s[1] |
| Declination | −69° 01′ 10.20″[1] |
| Apparent magnitude (V) | 13.76[2] |
| Characteristics | |
| Evolutionary stage | Main sequence[3] |
| Spectral type | O2V-III(n)((f*))[3] |
| U−B color index | −1.02[4] |
| B−V color index | −0.13[4] |
| Astrometry | |
| Proper motion (μ) | RA: 2.3[1] mas/yr Dec.: 3.1[1] mas/yr |
| Distance | 164,000 ly (50,000[5] pc) |
| Absolute magnitude (MV) | −5.7[3] |
| Details | |
| Mass | 97.6[6] M☉ |
| Radius | 10.9+1.7 −1.6[7] R☉ |
| Luminosity | 1,200,000+210,000 −370,000[7] L☉ |
| Surface gravity (log g) | 4.36+0.12 −0.33[7] cgs |
| Temperature | 58,000+1,600 −5,500[7] K |
| Rotational velocity (v sin i) | 153±24[7] km/s |
| Age | 0.4+0.8 −0.4[6] Myr |
| Other designations | |
| BI 253, VFTS 72, 2MASS J05373446-6901102, IRSF J05373446-6901102 | |
| Database references | |
| SIMBAD | data |
BI 253 is an O2V star in the Large Magellanic Cloud and is a primary standard of the O2 type. It is one of the hottest main-sequence stars known and one of the most-massive and most-luminous stars known.
(TRAPPIST/E. Jehin/ESO)
BI 253 was first catalogued in 1975 as the 253rd of 272 likely O and early B stars in the Large Magellanic Cloud.[4] In 1995, the spectral type was analysed to be O3 V, the earliest type defined at that time.[8]
When the classification of the earliest type O stars was refined in 2002, the complete lack of neutral helium or doubly ionised nitrogen lines in the spectrum led to BI 253 being placed in a new O2 V class. It was given a ((f*)) qualifier because of the very weak emission lines of helium and nitrogen.[9] The most recent published data gives a spectral type of O2V-III(n)((f*)), although it is unclear whether this is due to higher quality spectra or an actual change in the spectrum.[3][10]
BI 253 has been identified as a runaway star because of its relatively isolated position outside the main star-forming areas of 30 Doradus,[11][12] and because of its high space velocity. It was potentially ejected from the R136 cluster about a million years ago.[13]
