Using the ultraviolet capabilities of the NASA/ESA Hubble Space Telescope, astronomers have identified nine monster stars within the star cluster R136. With masses over 100 times that of the sun, they represent the largest sample of massive stars discovered to date and raise new questions regarding the formation of these star types.
The discovery was made using Hubble's Wide Field Camera 3 (WFC3) using the ultraviolent spatial resolution of the Space Telescope Imaging Spectrograph (STIS) in order to view the R136 star cluster in ultraviolet for the first time ever.
R136 measures just a few light-years across and is located in the Tarantula Nebula in the Large Magellanic Cloud approximately 170,000 light-years away from the Earth. Due to the ultraviolet energy radiated by its many hot, luminous and massive stars, the team was able to probe the ultraviolet emission of the star cluster.
In addition to discovering numerous stars with over 50 solar masses, the team revealed nine very massive stars with 100 times the mass of the sun and together, their brightness outshines the sun by a factor of 30 million.
As of now, the origins of behemoth stars such as those observed in the R136 are unknown.
"There have been suggestions that these monsters result from the merger of less extreme stars in close binary systems," said Saida Caballero-Nieves, co-author of the study. "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."
Future studies will need to continue analysis of the current datasets. Furthermore, the new optical STIS observation will allow researchers to search for close binary systems in R136 and give them the opportunity to observe gravitational waves produced by massive black hole binaries.
"Once again, our work demonstrates that, despite being in orbit for over 25 years, there are some areas of science for which Hubble is still uniquely capable," concludes Paul Crowther, lead author of the study.
The findings were published online in the Feb. 5 issue of the Monthly Notices of the Royal Astronomical Society.
