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  (Source: eso.org)
Scientists find star more than 300 times more massive than the sun.

A UK-led team of scientists say that R136a1 is the most massive star ever found.  According to the Associated Press, a new study finds that it shines millions of times more luminous than the sun.  The star, which is about 265 solar masses, had a birth weight of as much as 320 times that of our sun.

The mammoth star was found at the center of a star cluster in the Tarantula Nebula, located in the Large Magellanic Cloud, a neighboring galaxy about 165,000 light-years away from the Milky Way.

The celestial giant is losing mass through powerful winds and burns so brightly that it has already slimmed down considerably over its lifetime, said Paul Crowther, lead astrophysicist at the University of Sheffield in northern England.

"Unlike humans, these stars are born heavy and lose weight as they age," said Crowther. "R136a1 is already middle-aged and has undergone an intense weight loss program, shedding a fifth of its initial mass over that time, or more than fifty solar masses."

The team of scientists compared previous findings from the NASA/ESA Hubble Space Telescope with the new readings from the European Southern Observatory's Very Large Telescope, of two young clusters of stars. They found several stars with surface temperatures over 40,000 degrees — more than seven times hotter than the sun.

The findings from Crowther and his team can be found in the July edition of Monthly Notices of the Royal Astronomical Society.

In June, a team of NASA scientists discovered the most powerful gamma rays on record and physicists at the University of Oxford published a study about their findings on whether dark matter in the sun sustains life on Earth in this month's Physical Review Letters journal.



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Copy
By rs1 on 7/22/2010 3:33:54 PM , Rating: 2
This article seems to be essentially a trimmed-down version of the story that CNN posted yesterday:

http://www.cnn.com/2010/WORLD/europe/07/21/monster...

There's nothing wrong with reposting news articles from other sites, per se, but how about at least adding a few of your own contributions? For instance, I'd be interested in the science behind how this star manages to avoid collapsing in on itself and becoming a black hole. It's certainly massive enough to do so, so why doesn't it?




RE: Copy
By Josett on 7/22/2010 11:55:54 PM , Rating: 2
A good point, at last.

Mainly because electromagnetic repulsion (fusing Hydrogen atoms into Helium ones) still overcomes its gravitational pull. Within some few hundreds of thousands of years (perhaps less; I didn't make the calculations), it most probably will become a black-hole.

Simplistically, and to get it into perspective, the assumed initial minimum for a star-like object to collapse into a b-h, is about 2,5 solar masses. This one was about 320.

Cheers!


RE: Copy
By Executor115 on 7/24/2010 10:01:49 AM , Rating: 2
A star this massive almost certainly will not form a black hole. Above about 130 solar masses, a dying star will undergo a pair-instability supernova instead of a core-collapse one that lower mass stars undergo and which produce neutron stars and black holes. A pair-instability supernova occurs when a star's core grows so hot that it beings producing photons with energies greater then the mass of an electron-positron pair. While the pair will usually annihilate each other and release another photon in a random direction, when this is happening the photon is basically stopped and not helping the star against gravity. A star depends on photon pressure to keep it in hydrostatic equilibrium with gravity. As the temperature increases, more high-energy photons are created, but the distance each one travels before some kind of interaction is actually decreasing. For a few seconds, the star collapses, fusing its entire core, but the huge release of thermal energy is far more then the gravitational binding energy, so the star simply explodes without leaving anything behind.


RE: Copy
By Josett on 7/24/2010 7:20:16 PM , Rating: 2
Good point.

Had to Wiki it but anyway...

quote:
250 solar masses or more

A different reaction mechanism, photodisintegration , results after collapse starts in stars of at least 250 solar masses. This endothermic reaction (energy-absorbing) causes the star to continue collapse into a black hole rather than exploding due to thermonuclear reactions.


http://en.wikipedia.org/wiki/Pair-instability_supe...

Thanks for the pertinent post.

Cheers!


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