Hubble unveils nine new monster stars

Using the unique ultraviolet capabilities of the NASA/ESA Hubble Space Telescope, an international team of scientists has identified nine monster stars with masses over 100 times the mass of the sun in the star cluster R136.

R136 is only a few light-years across and is located in the Tarantula Nebula within the Large Magellanic Cloud, about 170,000 light-years away.

The young cluster hosts many extremely massive, hot and luminous stars whose energy is mostly radiated in the ultraviolet, NASA said in its report on Wednesday.

Apart from being extremely massive, the detected stars are also extremely bright. Together these nine stars outshine the Sun by a factor of 30 million.

The scientists also investigated the outflows of these nine starts and reported that they eject up to an Earth mass of material per month at a speed approaching one percent of the speed of light, resulting in extreme weight loss throughout their brief lives.

"The ability to distinguish ultraviolet light from such an exceptionally crowded region into its component parts, resolving the signatures of individual stars, was only made possible with the instruments aboard Hubble," said Paul Crowther, lead author of the study.

In 2010 Crowther and his team showed the existence of four stars within R136, each with over 150 times the mass of the Sun. Now, this new census has shown that there are five more stars with more than 100 solar masses in R136.

"There have been suggestions that these monsters result from the merger of less extreme stars in close binary systems," Saida Caballero-Nieves, a co-author of the study, explained.

This makes it the largest sample of very massive stars identified to date, however, the origin of the stars remains unclear.

"From what we know about the frequency of massive mergers, this scenario can't account for all the really massive stars that we see in R136, so it would appear that such stars can originate from the star formation process," Caballero-Nieves added.