"Astronomers have discovered the most massive stars known, including one at more than 300 times the mass of our sun – double the size that scientists thought heavyweight stars could reach.
These colossal stars are millions of times brighter than the sun and shed mass through very powerful winds.
The stellar discovery, which represents the first time that these hulking stars were individually identified, could help astronomers understand the behavior of massive stars, and how large they can be at birth.
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More massive than thought
In the NGC 3603 nebula, the astronomers were also able to directly measure the masses of two stars that belong to a double-star system. The stars A1, B and C in this cluster have estimated birth masses of close to or above 150 solar masses.
These ultra-heavy stars are extremely rare and only form within the densest star clusters. Detecting them requires the sharp resolving power of the Very Large Telescope's infrared instruments.
In the study, the researchers estimated the maximum possible mass for stars within the two clusters, and the relative number of the most massive stars. Their findings have caused them to reevaluate current estimates for how large these stars can be.
"The smallest stars are limited to more than about 80 times more than Jupiter, below which they are 'failed stars' or brown dwarfs," said Olivier Schnurr, a research team member from the Astrophysikalisches Institut Potsdam in Germany. "Our new finding supports the previous view that there is also an upper limit to how big stars can get, although it raises the limit by a factor of two, to about 300 solar masses."
Within R136, only four of the approximately 100,000 stars found in the cluster weighed more than 150 solar masses at birth. Yet the sheer intensity of their wind and radiation account for nearly half of R136's entire wind and radiation power.
R136a1 alone emits energy by more than a factor of 50 compared to the entire Orion Nebula, which is the closest region of massive star formation to Earth. "More in:
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http://www.space.com/scienceastronomy/eso-massive-stars-discovered-100721.html-
http://www.astronomynow.com/news/n1007/21massive/What is strange about this star is that estimated limit for the mass of a star is about 150-200 solar masses (
http://arxiv.org/abs/astro-ph/0501135 ) R136a1 easily exceeds this limit which. Maybe this star are a close binary with total mass of 265 solar masses ?
However the preprint of the paper from researchers suggests that no, this would not be a binary star which challenges the model for star mass limits.
The preprint of the paper on the star R136a1 can be read here:
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http://arxiv.org/pdf/1007.3284v1I did a simulation to demonstrate the dimensions of this star with some other stars of known spectral type similar ( not Red Giants or Supergiants), note that even the giant Rigel becomes relatively small near the monster R136a1:
[Edit by Dan: Fixed link]