R136a1
R136a1 is the brightest and most massive star known to be stable. He is in super star cluster R136 near the center of the 30 Doradus complex ( the Tarantula Nebula or NGC 2070 ) in the Large Magellanic Cloud. The star is part of a whole cluster of young, massive giant stars; the stellar density there is 100,000 times higher than in the neighborhood of our sun. R136a1 is about 1 million years old, has of formerly 320 solar masses currently still 265 at 1,300 times the solar diameter, emits ten million times brighter than the sun, and would, if he were in our solar system, thus the luminosity of the sun almost to the same extent surpass, as the sun outshines the moon. R136a1 has a surface temperature of over 40,000 degrees Celsius, which is about seven times hotter than our Sun. The distance of the star from Earth is about 160000-165000 light years.
Discovery history
R136a1 was discovered in the 1980s. Previously, the center of the cluster than R136a was known; there was a hand investigations which started from a single star of several thousand solar masses, while others attributed it to a very dense cluster of stars. Finally, it was the latter hypothesis confirmed and R136a are resolved into individual components, the brightest was designated R136a1. In 2010, a team of astronomers led by Paul Crowther published a reanalysis in which various spectroscopic archive data were combined. In particular, data from VLT / SINFONI from 2005 were used, which allowed for the first time in the near IR, the light of the stars of R136a to separate spectroscopically clean. The comparison of the observations with star developing models suggests a mass of solar masses, which star is R136a1 the most massive known to be stable. It can not be excluded that it is at R136a1 two, also tightly packed stars, the smaller star but then would be considerably smaller ( Crowther self-limited one might not have recognized companion star to a maximum of about 20 solar masses ).
Implications for stellar physics
Even before the discovery of this star has been conjectured by several researchers that until recently accepted upper mass limit was seized too deep for star of 150 solar masses. Although it can not be ruled out that it is not a single object, but two tightly packed stars at R136a1, would in most scenarios even then masses above 150 solar masses necessary. The modeled for R136a1 mass is thus a clear indication that stands in the mass limit previously adopted. Due to their high mass such stars have a very high rate of fusion in its core, that is, in a relatively much larger area of the star matter is converted into energy, which would prevent any further increase in mass by radiation by " blowing off " of matter. These extremely strong winds should prevent radiation in theory, such a mass formation. Therefore, it has been a mystery to astronomers for a long time, as R136a1 and other hypergiants could be so hard. Recent N-body computer simulations suggest, however, that such giants created by fusion processes of several stars in young star clusters, and so the current theory of star formation and stellar evolution still has remains valid and need not be modified.