page_title: R136a1
section_title: Surroundings
hierarchical_section_title: R136a1 / Surroundings
caption_attribution_description: English: Using a combination of instruments on ESO’s Very Large Telescope, astronomers have discovered the most massive stars to date, some weighing at birth more than 300 times the mass of the Sun, or twice as much as the currently accepted limit of 150 solar masses. The most extreme of these stars was found in the cluster RMC 136a (or R136 as it is more usually named). Named R136a1, it is found to have a current mass of 265 times that of the Sun. Being a little over a million years old, R136a1 is already “middle-aged” and has undergone an intense weight-loss programme, shedding a fifth of its initial mass over that time, or more than fifty solar masses. It also has the highest luminosity, close to 10 million times greater than the Sun. R136 is a cluster of young, massive and hot stars located inside the Tarantula Nebula, in one of the neighbourhood galaxies of the Milky Way, the Large Magellanic Cloud, 165 000 light-years away. R136 contains so many stars that on a scale equivalent to the distance between the Sun and the nearest star there are tens of thousands of stars. Hundreds of these stars are so incredibly bright that if we were to sit on a (hypothetical) planet in the middle of the cluster the sky would never get dark. This montage shows a visible-light image of the Tarantula nebula as seen with the Wide Field Imager on the MPG/ESO 2.2-metre telescope (left) along with a zoomed-in visible-light image from the Very Large Telescope (middle). A new image of the R136 cluster, obtained with the near-infrared MAD adaptive optics instrument on the Very Large Telescope is shown in the right-hand panel, with the cluster itself at the lower right. The MAD image provides unique details on the stellar content of the cluster.
context_page_description: RMC 136a1 has the highest mass and luminosity of any known star, at 315 M☉ and 8.7 million L☉, and is also one of the hottest, at around 53,000 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. Its cluster can be seen under mild magnification in the far southern celestial hemisphere, at magnitude 7.25; to perceive the outline of this star requires good telescopic magnification as it is five orders of magnitude fainter — it lies at a distance of about 49.97 kiloparsecs in the leading edge of a neighbouring highly dispersed galaxy, which has many large nebulae with highly active star formation, the Large Magellanic Cloud.
context_section_description: The R136a system at the core of R136 is a dense luminous knot of stars containing at least 12 stars, the most prominent being R136a1, R136a2, and R136a3, all of which are extremely luminous and massive WN5h stars. R136a1 is separated from R136a2, the second brightest star in the cluster, by 5,000 AU.
  R136 is located approximately 157,000 light-years away from Earth in the Large Magellanic Cloud, positioned on the south-east corner of the galaxy at the centre of the Tarantula Nebula, also known as 30 Doradus. R136 itself is just the central condensation of the much larger NGC 2070 open cluster.
  For such a distant star, R136a1 is relatively unobscured by interstellar dust. The reddening causes the visual brightness to be reduced by about 1.8 magnitudes, but only around 0.22 magnitudes in the near infrared.
caption: Zooming in from the Tarantula Nebula to the R136 cluster, with R136a1/2/3 visible as the barely resolved knot at bottom right.
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