| Observation data EpochJ2000 EquinoxJ2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 05h 38m 39.144s[1] |
| Declination | −69° 06′ 21.30″[1] |
| Apparent magnitude (V) | 13.38[2] |
| Characteristics | |
| Evolutionary stage | Wolf–Rayet star |
| Spectral type | WN6[3] |
| B−Vcolor index | -0.10[2] |
| Astrometry | |
| Proper motion (μ) | RA: 1.680[1]mas/yr Dec.: 0.512[1]mas/yr |
| Parallax (π) | 0.0288±0.0159 mas[1] |
| Distance | 165,000 ly (50,600 pc) |
| Absolute magnitude (MV) | -8.11[3] |
| Absolute bolometric magnitude (Mbol) | -12.0[3] |
| Details | |
| Mass | 226 (highly uncertain)[3] M☉ |
| Radius | 37.5[3] R☉ |
| Luminosity | 5,000,000[3] L☉ |
| Luminosity (visual, LV) | 141,000[3] L☉ |
| Temperature | 45,000[3] K |
| Age | 7.5[4] Myr |
| Other designations | |
| Brey 79,NGC 2070 MEL J,SSTISAGEMC J053839.14-690621.2,BAT99 98,LMC AB12, Melnick 49,2MASS J05383914-6906211,UCAC4 105‑014273, Gaia EDR3 4657679654981424640 | |
| Database references | |
| SIMBAD | data |
BAT99-98 is aWolf–Rayet star located in theLarge Magellanic Cloud, in NGC 2070 near theR136 cluster in theTarantula Nebula (30 Doradus). At 226 M☉ and 5,000,000 L☉ it is themost massive known star, and close to one of the mostluminousstars currently known.[3]
A 1978 survey carried out by Jorge Melnick covered the30 Doradus region and found six new Wolf–Rayet (WR) stars, all belonging to theWN sequence. The survey observed stars that were above[clarification needed]apparent magnitude 14 and within 2arcminutes of the centre of the 30 Doradus nebula, and the star now known as BAT99‑98 was labelled as star J. It was found to have a magnitude of 13.5 and aspectral type of WN5.[5]
The following year, thirteen new WR stars in the Large Magellanic Cloud were reported, one of which was Mel J. It was numbered 12, and referred to as AB12, or LMC AB12 to distinguish it from the better-knownAB stars in theSmall Magellanic Cloud.[6]
Melnick conducted another study of stars inNGC 2070 and gave BAT99-98 the number 49, reclassifying its spectral type as WN7.[7]
Neither the AB12 nor the Mel J designation is in common use, although "Melnick 49" is sometimes seen. More commonly, LMC Wolf–Rayet stars are referred to by R (Radcliffe Observatory) numbers, Brey (Breysacher catalogue numbers[8]), orBAT99 numbers.[9]
BAT99‑98 is located near the R136 cluster and has similarmass–luminosity properties to the massivestars in the cluster itself. It is estimated that the star held 250 M☉ at its birth and has since lost 20 M☉.[3] It sheds a large amount of mass through astellar wind that moves at1,600 km/s.[3] The star has a surface temperature of45,000 K and a luminosity of 5,000,000 L☉. Although the star isvery luminous due to its high temperature, much of that light isultraviolet and invisible tohumans – making it 141,000 times brighter than the Sun visually. It is now classified as a WN6 star, and models suggest that it is 7.5 million years old.
The future of BAT99-98 depends on its mass loss. It is thought that stars this massive can never lose enough mass to avoid a catastrophic end. The result is likely to be asupernova,hypernova,gamma-ray burst, or perhaps almost no visible explosion, leaving behind ablack hole orneutron star. The exact details depend heavily on the timing and amount of themass loss, with current models not fully reproducing observed stars, but the majority of massive stars in theLocal Group are expected to produceType Ib or Ic supernovae, sometimes with a gamma-ray burst, and leave behind a black hole.[10] However, for some stars of exceptionally high mass, the supernova event is triggered bypair instability and leaves behind no remnant at all.[11]
