R136

Lore & Background

R136 was first named as an unresolved stellar object in the Radcliffe Observatory Magellanic Clouds catalogue and was catalogued as HD 38268 and Wolf–Rayet star Brey 82. It is now known to include 72 class O and Wolf–Rayet stars within 5 parsecs (20 arc seconds) of the cluster centre. The cluster is thought to be less than 2 million years old; none of its member stars are significantly evolved, and none are thought to have exploded as supernova.

Consequently, the cluster contains no red supergiants, blue hypergiants, or luminous blue variables. The brightest stars are WNh, O supergiants, and OIf/WN slash stars, all extremely massive fully convective stars. A small number of B-type main sequence stars have been detected in the outskirts, but less massive and less luminous stars cannot be resolved from the dense core at the distance of the LMC.

R136 was first resolved into three components: R136a, R136b, and R136c. R136a, the bright knot at the centre, was resolved using speckle interferometry and eventually space-based observations into as many as 24 components, dominated by R136a1, R136a2, and R136a3, all three being extremely massive WNh stars several million times more luminous than the sun.

Within the central 5 parsecs there are 32 of the hottest type O stars (O2.0–3.5), 40 other O stars, and 12 Wolf–Rayet stars, mostly of the extremely luminous WNh type. Within 150 parsecs there are a further 19 Wolf–Rayet stars. Several runaway stars have been associated with R136, including VFTS 682.

Reader's Guide

R136 produces most of the energy that makes the Tarantula Nebula visible, and its estimated mass of 450,000 solar masses suggests it may become a globular cluster in the future. The cluster has around 200 times the stellar density of a typical OB association such as Cygnus OB2. The central R136 concentration is about 2 parsecs across, although the whole NGC 2070 cluster is much larger.

The cluster contains many of the most massive and luminous stars known, including R136a1. The extreme number and concentration of young massive stars in this part of the LMC qualifies it as a starburst region. R136 is associated with other notable clusters in the Tarantula Nebula, such as Hodge 301 (an older massive star cluster) and NGC 2060 (a smaller open cluster near R136), as well as LMC N79, which contains another super star cluster in the Large Magellanic Cloud.