R136

For the road in Dublin, see R136 road.

R136 (formally 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. 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 stars within 5 parsecs (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.

Properties

File:Grand star-forming region R136 in NGC 2070 (infrared, captured by the Hubble Space Telescope).jpg

R136 in infrared (Hubble Space Telescope)

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 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 are significantly evolved and none are thought to have exploded as supernovae. 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.

Components

File:Runaway star speeding from 30 Doradus.jpg

Runaway star speeding from 30 Doradus, image taken by The Hubble Space Telescope

The cluster R136 contains many of the most massive and luminous stars known, including R136a1. Within the central 5 parsecs there are 32 of the hottest type O stars (O2 - O3.5), 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 stars 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 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.

Name	Right ascension	Declination	V	Spectral type	MV	Temperature (K)	Luminosity (L☉)
R136a1	05h 38m 42.39s	−69° 06′ 02.9″	12.23	WN5h	-7.6	56,000	8,700,000
R136a2	05h 38m 42.40s	−69° 06′ 02.9″	12.34	WN5h	-7.8	53,000	4,900,000
R136a3	05h 38m 42.33s	−69° 06′ 03.3″	12.97	WN5h	-7.4	53,000	3,200,000
R136a4	05h 38m 42.34s	−69° 06′ 02.6″	13.41	(O3V)	-5.7	~50,000	980,000
R136a5	05h 38m 42.43s	−69° 06′ 02.7″	13.71	O2If*	-6.3	46,000	1,250,000
R136a6	05h 38m 42.29s	−69° 06′ 03.4″	13.35	(O3V)	-5.8	~50,000	1,000,000
R136a7	05h 38m 42.48s	−69° 06′ 02.6″	13.97	O3III(f*)	-5.7	47,000	630,000
R136a8	05h 38m 42.37s	−69° 06′ 01.9″	14.2	(O3V)	-5.5	~50,000	760,000
R136b	05h 38m 42.74s	−69° 06′ 03.8″	13.24	WN9ha	-7.3	45,000	2,000,000
R136c	05h 38m 42.90s	−69° 06′ 04.8″	12.86	WN5h	-7.9	51,000	3,000,000

This list is incomplete; you can help by expanding it.

See also

• Hodge 301, an older massive star cluster in Tarantula Nebula.
• NGC 2060, a smaller open cluster near R136.

Further reading

• ESA Hubble, Symphony of colours in the Tarantula, 15 December 2004
• R 136 in the Aladin previewer

External links

• SIMBAD RMC 136
• NED RMC 136

• Simbad data for RMC 136