R136a1

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R136a1 (artist's impression)

R136a1 is the brightest and most massive of all stars known to be stable . It is located in the 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 star density there is 100,000 times higher than in the vicinity of our sun. R136a1 is about 1 million years old and has a mass of about 35 times the solar diameter . It is believed that it was originally around 320 times as heavy as the sun , but due to its enormous radiant power - it is ten million times brighter than the sun - it has since lost matter due to stellar winds . If it were in our solar system , it would exceed the luminosity of the sun almost as much as the sun outshines the moon . R136a1 has a surface temperature of more than 40,000 degrees Celsius and is therefore around seven times hotter than our sun. The distance of the star from the earth is approximately 160,000 to 165,000 light years.

Discovery story

R136a1 was discovered in the 1980s. Previously, the center of the cluster was known as R136a ; On the one hand, there were studies that assumed a single star with several thousand solar masses, while others assumed a very dense cluster of stars. Finally, the latter hypothesis was confirmed and R136a was broken down into individual components, the lightest being given the designation R136a1. In 2010, a team of astronomers led by Paul Crowther published a new analysis in which various spectroscopic archive data were combined. In particular, data from VLT / SINFONI from 2005 were used, which made it possible for the first time to separate the light of the stars from R136a spectroscopically cleanly in the near IR. A comparison of the observations with stellar evolution models suggests a mass of solar masses, making R136a1 the most massive star known to be stable. It cannot yet be ruled out that R136a1 is two closely spaced stars, although the smaller star would then be considerably smaller (Crowther himself limits a perhaps not yet recognized partner star to a maximum of around 20 solar masses).

Implications for Stellar Physics

Even before this star was found, various researchers speculated that the upper mass limit of 150 solar masses recognized until recently was too low. Although it cannot be ruled out that R136a1 is not a single object, but rather two closely spaced stars, in most scenarios masses above 150 solar masses would still be necessary. The mass modeled for R136a1 is thus an indication that contradicts the previously assumed mass limit. Because of their high mass, such stars have a very high rate of fusion in their core; that is, in a relatively much larger area of ​​the star, matter is converted into energy , which, according to the theory , should prevent any further increase in mass through radiation ("blowing away" the matter). Hence, it has long been a mystery to astronomers how R136a1 and other hypergiants got so heavy. However, the latest N-body computer simulations suggest that such giants are formed by merging processes of several stars in young star clusters and that the current theory of star formation and evolution is still valid and does not need to be modified.

Individual evidence

  1. ↑ http://mnras.oxfordjournals.org/content/408/2/731.full.pdf+html p.740 Table 5
  2. ↑ Sebastian Boblest, Thomas Müller, Günter Wunner: Special and general theory of relativity: Basics, applications in astrophysics and cosmology as well as relativistic visualization . Springer, Berlin and Heidelberg 2015, ISBN 978-3-662-47767-0 , pp. 305 ( limited preview in Google Book Search).
  3. ↑ Der Standard, Austria, brightest giant star discovered
  4. ↑ VLT: Astronomers discover stellar giants at astronews.com , accessed July 30
  5. ↑ “Star monsters ” with 300 solar masses discovered at www.scinexx.de , accessed on July 30, 2010
  6. ↑ Most massive star on record found in neighboring galaxy on The Guardian , accessed July 30, 2010
  7. ↑ Weigelt, G .; Baier, G .: R136a in the 30 Doradus nebula resolved by holographic speckle interferometry . In: Astronomy and Astrophysics . 150, No. 1, 1985, pp. L18-L20. bibcode : 1985A & A ... 150L..18W .
  8. ↑ Crowther, PA; Schnurr, O .; Hirschi, R. et al .: The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150M solar stellar mass limit . In: MNRAS . 408, No. 2, 2010, pp. 731-751. bibcode : 2010MNRAS.408..731C .
  9. ↑ Sueddeutsche.de: Double star at R136a1 according to co-discoverer Crowther possible
  10. ↑ n-tv.de: Astronomers crack a secret

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