R136b is a

blue supergiant A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They are usually considered to be those with luminosity class I and spectral class B9 or earlier, although sometimes A-class supergiants are also deemed blu ...

star in the

R136 R136 (formerly known as RMC 136 from the Radcliffe Observatory Magellanic Clouds catalogue) 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. W ...

cluster in the

Large Magellanic Cloud The Large Magellanic Cloud (LMC) is a dwarf galaxy and satellite galaxy of the Milky Way. At a distance of around , the LMC is the second- or third-closest galaxy to the Milky Way, after the Sagittarius Dwarf Spheroidal Galaxy, Sagittarius Dwarf ...

. It is one of the most massive and most luminous stars known. It is found in the dense

open cluster An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

at the centre of NGC 2070 in the

Tarantula Nebula The Tarantula Nebula (also known as 30 Doradus) is a large H II region in the Large Magellanic Cloud (LMC), forming its south-east corner (from Earth, Earth's perspective). Discovery The Tarantula Nebula was observed by Nicolas-Louis de Lacaill ...

. R136b has the spectral type of Wolf–Rayet star, with strong

emission line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

s. Although it shows enhanced helium and nitrogen at its surface, it is still a very young star, still burning hydrogen in its core via the

CNO cycle In astrophysics, the carbon–nitrogen–oxygen (CNO) cycle, sometimes called Bethe–Weizsäcker cycle, after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker, is one of the two known sets of fusion reactions by which stars convert h ...

, and still effectively a

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

object. Others studies classify the spectrum as a hot supergiant with emission lines of ionised nitrogen and helium, still considering it to be a young star at the core-hydrogen-burning stage, the unusual spectrum caused by strong convection and stellar winds.

References

{{DEFAULTSORT:R136b Stars in the Large Magellanic Cloud Extragalactic stars Tarantula Nebula O-type supergiants ? Dorado Large Magellanic Cloud