| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| 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−V color 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 | |
| Database references | |
| SIMBAD | data |
BAT99-98 is a Wolf–Rayet star located in the Large Magellanic Cloud, in NGC 2070 near the R136 cluster in the Tarantula Nebula (30 Doradus). At 226 M☉ and 5,000,000 L☉ it is the most massive known star, and close to one of the most luminous stars currently known. [3]
A 1978 survey carried out by Jorge Melnick covered the 30 Doradus region and found six new Wolf–Rayet (WR) stars, all belonging to the WN sequence. The survey observed stars that were above[ clarification needed ] apparent magnitude 14 and within 2 arcminutes 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 a spectral 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-known AB stars in the Small Magellanic Cloud. [6]
Melnick conducted another study of stars in NGC 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] ), or BAT99 numbers. [9]
BAT99‑98 is located near the R136 cluster and has similar mass–luminosity properties to the massive stars 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 a stellar wind that moves at 1,600 km/s . [3] The star has a surface temperature of 45,000 K and a luminosity of 5,000,000 L☉. Although the star is very luminous due to its high temperature, much of that light is ultraviolet and invisible to humans – 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 a supernova, hypernova, gamma-ray burst, or perhaps almost no visible explosion, leaving behind a black hole or neutron star. The exact details depend heavily on the timing and amount of the mass loss, with current models not fully reproducing observed stars, but the majority of massive stars in the Local Group are expected to produce Type 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 by pair instability and leaves behind no remnant at all. [11]
Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification.
NGC 3603 is a nebula situated in the Carina–Sagittarius Arm of the Milky Way around 20,000 light-years away from the Solar System. It is a massive H II region containing a very compact open cluster HD 97950.
Sher 25 is a blue supergiant star in the constellation Carina, located approximately 25,000 light years from the Sun in the H II region NGC 3603 of the Milky Way. It is a spectral type B1Iab star with an apparent magnitude of 12.2. Its initial main sequence mass is calculated at 60 times the mass of the Sun, but a star of this type will have already lost a substantial fraction of that mass. It is unclear whether Sher 25 has been through a red supergiant phase or has just evolved from the main sequence, so the current mass is very uncertain.
R136 is the central concentration of stars in the NGC 2070 star cluster, which lies at the centre of the Tarantula Nebula in the Large Magellanic Cloud. When originally named it was an unresolved stellar object but is now known to include 72 class O and Wolf–Rayet stars within 5 parsecs of the centre of the cluster. The extreme number and concentration of young massive stars in this part of the LMC qualifies it as a starburst region.
R136b is a blue supergiant star in the R136 cluster in the Large Magellanic Cloud. It is one of the most massive and most luminous stars known. It is found in the dense R136 open cluster at the centre of NGC 2070 in the Tarantula Nebula.
R136a1 is one of the most massive and luminous stars known, at nearly 200 M☉ and nearly 4.7 million L☉, and is also one of the hottest, at around 46,000 K. It is a Wolf–Rayet star at the center of R136, the central concentration of stars of the large NGC 2070 open cluster in the Tarantula Nebula in the Large Magellanic Cloud. The cluster can be seen in the far southern celestial hemisphere with binoculars or a small telescope, at magnitude 7.25. R136a1 itself is 100 times fainter than the cluster and can only be resolved using speckle interferometry.
Melnick 42 is a massive blue supergiant star in the Tarantula Nebula in the Large Magellanic Cloud located in the constellation Dorado. Although it is only 21 times the size of the sun, its high temperature of 47,300 K makes it one of the most luminous stars of the Tarantula Nebula at 3,600,000 L☉. It is less than two parsecs from the centre of the R136 cluster, although that is well outside the central core.
VFTS 682 is a Wolf–Rayet star in the Large Magellanic Cloud. It is located over 29 parsecs (95 ly) north-east of the massive cluster R136 in the Tarantula Nebula. It is 138 times the mass of the Sun and 3.2 million times more luminous, which makes it one of the most massive and most luminous stars known.
R136a2 is a Wolf-Rayet star residing near the center of the R136, the central concentration of stars of the large NGC 2070 open cluster in the Tarantula Nebula, a massive H II region in the Large Magellanic Cloud which is a nearby satellite galaxy of the Milky Way. It has one of the highest confirmed masses and luminosities of any known star, at about 151 M☉ and 3.5 million L☉ respectively.
R136c is a star located in R136, a tight knot of stars at the centre of NGC 2070, an open cluster weighing 450,000 solar masses and containing 10,000 stars. At 142 M☉ and 3.8 million L☉, it is the one of the most massive stars known and one of the most luminous, along with being one of the hottest, at over 40,000 K. It was first resolved and named by Feitzinger in 1980, along with R136a and R136b.
HD 38282 is a massive spectroscopic binary star in the Tarantula Nebula, consisting of two hydrogen-rich Wolf-Rayet stars.
R136a3 is a Wolf–Rayet star in R136, a massive star cluster located in Dorado. It is located near R136a1, the most massive and luminous star known. R136a3 is itself one of the most massive and most luminous stars known at about 179 times more massive and 5 million times more luminous than the Sun.
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.
Melnick 34, also called BAT99-116, is a binary Wolf–Rayet star near R136 in the 30 Doradus complex in the Large Magellanic Cloud. Both components are amongst the most massive and most luminous stars known, and the system is the most massive known binary system.
AB8, also known as SMC WR8, is a binary star in the Small Magellanic Cloud (SMC). A Wolf-Rayet star and a main sequence companion of spectral type O orbit in a period of 16.638 days. It is one of only nine known WO stars, the only Wolf-Rayet star in the SMC not on the nitrogen sequence, and the only Wolf-Rayet star in the SMC outside the main bar.
R145 is a spectroscopic binary star in the Tarantula Nebula in the Large Magellanic Cloud located in the constellation Dorado. Both components are amongst the most luminous known.
R71 is a star in the Large Magellanic Cloud (LMC) in the constellation Mensa. It is classified as a luminous blue variable and is one of the most luminous stars in the LMC. It lies three arc-minutes southwest of the naked-eye star β Mensae.
