R136 (formerly known as RMC 136 from the

Radcliffe Observatory Radcliffe Observatory was the astronomical observatory of the University of Oxford from 1773 until 1934, when the Radcliffe Trustees sold it and built a new observatory in Pretoria, South Africa. It is a Grade I listed building. Today, the ...

Magellanic Clouds The Magellanic Clouds (''Magellanic system'' or ''Nubeculae Magellani'') are two irregular dwarf galaxies in the southern celestial hemisphere. Orbiting the Milky Way galaxy, these satellite galaxies are members of the Local Group. Because bo ...

catalogue) is the central concentration of stars in the NGC 2070 star cluster, which lies at the centre of 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's perspective). Discovery The Tarantula Nebula was observed by Nicolas-Louis de Lacaille durin ...

in the Large Magellanic Cloud. When originally named it was an unresolved stellar object (catalogued as HD 38268 and Wolf-Rayet star Brey 82) but is now known to include 72 class O and

Wolf–Rayet star 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 ...

s within 5

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

s (20 arc seconds) 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 A starburst is an astrophysical process that involves star formation occurring at a rate that is large compared to the rate that is typically observed. This starburst activity will consume the available interstellar gas supply over a timespan that ...

Properties

R136 produces most of the energy that makes the Tarantula Nebula visible. The estimated mass of the cluster is 450,000 solar masses, suggesting it may become a

globular cluster A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...

in the future. R136 has around 200 times the stellar density of a typical OB association such as Cygnus OB2. The central R136 concentration of the cluster is about 2 parsecs across, although the whole NGC 2070 cluster is much larger. R136 is thought to be less than 2 million years old. None of the member stars is significantly evolved and none is thought to have exploded as supernova. The brightest stars are WNh, O supergiants, and OIf/WN slash stars, all extremely massive fully convective stars. There are no red supergiants, blue hypergiants, or luminous blue variables within the cluster. A small number of class B stars have been detected in the outskirts of the cluster, but less massive and less luminous stars cannot be resolved from the dense cluster core at the large distance of the LMC.

R136a

R136a is the bright knot at the centre of R136. It consists of eight extremely massive stars, three of them Wolf-Rayet stars and the rest early O-class stars.

Components

The cluster contains many of the most massive and luminous stars known, including

R136a1 R136a1 (short for RMC 136a1) is one of the most massive and luminous stars known, at and nearly 4.7 million , and is also one of the hottest, at around . It is a Wolf–Rayet star at the center of R136, the central concentration of s ...

. 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 325 O stars and 19 Wolf-Rayet stars. Several

runaway star In astronomy, stellar kinematics is the Observational astronomy, observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar Velocity, velocities in the Milky W ...

s have been associated with R136, including VFTS 682. R136 was first resolved into three components R136a, R136b, and R136c. R136a was resolved using

speckle interferometry Speckle imaging describes a range of high-resolution astronomical imaging techniques based on the analysis of large numbers of short exposures that freeze the variation of atmospheric turbulence. They can be divided into the shift-and-add ("'' ...

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.

Gallery

R136 observed with WFC3.jpg, R136 observed with Hubble's WFC3. Runaway star speeding from 30 Doradus.jpg, Runaway star speeding from 30 Doradus, image taken by the Hubble Space Telescope. Grand star-forming region R136 in NGC 2070 (infrared, captured by the Hubble Space Telescope).jpg, R136 in infrared (Hubble Space Telescope)

References

External links

* SIMBA
RMC 136
* NE
RMC 136
{{DEFAULTSORT:R136 Super star clusters Open clusters Tarantula Nebula 038268 ? Large Magellanic Cloud Star-forming regions Durchmusterung objects Dorado (constellation)