A team of astronomers has found nine stars 30 million times brighter and 100 times heavier than the Sun in the star cluster R136 seen by the NASA/ESA Hubble Space Telescope. The team says that this is the first time to examine R136 by probing the ultraviolet emission of the young cluster, making it the biggest sample of very massive stars found so far.
Lead author Paul Crowther from the University of Sheffield in the UK, explains that R136 is only 170,000 light-years away from Earth, positioned in the Tarantula Nebula within the Large Magellanic Cloud. Crowther’s team has already confirmed in 2010 that there are four stars within R136, which have 150 solar masses but now they have found five more with 100 times the mass of the Sun.
These extremely massive and bright stars’ energy is mostly radiated in the ultraviolet. Moreover, the weight of the material outflows from these reaches up to mass similar that of Earth, ejected at one percent of the speed of light.
“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,” explains Crowther. “Together with my colleagues, I would like to acknowledge the invaluable work done by astronauts during Hubble’s last servicing mission: they restored STIS (Space Telescope Imaging Spectrograph) and put their own lives at risk for the sake of future science!”
Additionally, the team says that R136 data, as well as information gathered from other clusters, leads to more uncertainties about the stars’ origin. Nevertheless, the team will attempt to answer the questions through further data analysis.
“There have been suggestions that these monsters result from the merger of less extreme stars in close binary systems,” co-author Saida Caballero-Nieves asserts. “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.”