Tarantula’s Superstar


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The Tarantula’s Superstar

The star at the very centre of this picture, called R136a, turns out to be nearly ten million times brighter than the Sun. It’s now revealed to be by far the most massive star ever discovered. Its current mass is 265 times that of the Sun and it probably had 320 solar masses at birth. The superstar lies 165,000 light-years away in a neighbouring galaxy, the Large Magellanic Cloud, at the very heart of a huge nebula aptly called the Tarantula. The European Southern Observatory (ESO) obtained this infra-red image with the MAD adaptive optics instrument on the Very Large Telescope in Chile. Credit: ESO/P. Crowther/C.J. Evans

The report by Paul Crowther of Sheffield and his colleagues, released today, is in press in the Monthly Notices of the Royal Astronomical Society, under the title “The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Mstellar mass limit.”.

The Tarantula Nebula in a mosaic of images from ESO's 2.2-metre telescope. Credit: M. Schirmer, T. Erben, M. Lombardi, IAEF Bonn, ESO

What fascinates me is to picture the young superstar R136a, and her obese sisters b and c, hurling off gas equivalent to dozens of suns. Combined with the pressure of their intense radiation, the resulting winds have shaped the Tarantula Nebula with its spidery arms that stretch 500 light-years from the stormy centre.

The theorists will now have a merry time explaining how such a massive star could form from a gas cloud without breaking up into a swarm of normal objects. The discovery also lends credence to an idea that very massive stars can explode as supernovae, scattering chemical elements into space, without leaving any relic like a neutron star or black hole.