Interesting article in Science Daily about mass observations in clusters. They find that there are neutron stars that may have had masses above 40 times that of the sun. Current theory suggests stars above 25 masses should collapse into a black hole.

http://www.sciencedaily.com/releases...1103080649.htm

How will this change current thinking about the formation of black holes?

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Keeper of the Jabberwock

I think what you mean is the progenitor star had 40 solar masses. The upper mass limit for a neutron star is a bit less than 3 solar masses.

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Phil Plait
The Bad Astronomer
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We have different models for how one of these high mass stars ages. Different models in some respects means different guesses. We are not really sure what mechanisms are involved, and how much they are involved, so we are not certain what the maximum possible size is for the original star, what The Bad Astronomer means by progenitor. Some of our models say that if the progenitor is 25 solar masses or more, then it should die leaving a black hole instead of a neutron star. Other models say that the progenitor could be as massive as 40 of our suns, which is what this one comes in at.

Interestingly, some of our models have a range of masses for black hole production. The progenitor leaves a black hole if it's mass is 40, but but leaves nothin if its mass is much more, like 250 solar masses. I forget what those numbers are right now; maybe someone else will have them handy.

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There are ten kinds of people. Those that understand binary, and those that do not.

Well, if a star forms with 250 solar masses (highly unlikely) it won't be stable. It will destroy itself long before it has a chance to become a black hole.

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"Last Thursday, in a major breakthrough for the science of astrology, everyone born under the sign of scorpio was run over by milk trucks...."

Tell that to the Pistol.

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There are ten kinds of people. Those that understand binary, and those that do not.

It is believed that in the very early universe, when it was almost pure hydrogen and helium, that stars could form that had masses of up to or even exceeding 1000 solar masses.

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T. Anderson

Correct. The absense of dust in the primordal cloud meant that proto stars could not radiate heat as efficiently as they could with even a slight salting of heavy elements. Because of this thei retained their heat longer, resisting condensing into proplyds. Whereas proto stars now begin their collapse at around eight Kelvin, these original Population III stars would begin their collapse at more like room temperature, perhaps 300 or 400 Kelvin. This led to some truly massive first generation stars, running as high as 100,000 solar masses. Entire proto galaxies sometimes would collapse into a single star. I have seen some models even run another order of magnitude higher for their mass. It's all guesswork though because we have none today to examine.

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What's a little mayhem between friends?

And note that one key advantage of very massive stars is they evolve very quickly and churn out metals real fast. This may help explain why zero-metallicity gas is never observed, even in the very early universe. I did once hear of a proposal to build a telescope so powerful that it could actually observe these supermassive stars-- in effect, seeing not only the first stars, but the first star! I hope they build it.

Well, such beliefs in very high mass early universe stars would be far more credible if some were actually observed. Until then, such supermassive stars remain hypotheses in search of confirmation.

I'd wait on that.

I'm less pessimistic. The laws of stellar astronomy are among the best-known, best-tested in all of astronomy. Which may not be saying all that much...

If you extrapolate current relationships between stellar mass and their lifespans, you get crazy numbers like stars living on main sequence for less than a human lifetime. What you cannot know in such an exercise is whether there is a knee in the diagram, a point in which one quantity changes a great deal more than it had before.

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There are ten kinds of people. Those that understand binary, and those that do not.

There's no need to reason by "extrapolation", instead you just solve the stellar structure equations. It's just physics, and there can always be surprises, but I don't think it's all that speculative really. I could be wrong.

I thought there was a limit to the size of stars. When the force exerted by the light pressure becomes equal to the force of gravity, no more matter can accrete to the star, because the light will push it away.

This is true in principle, but in practice, the star's interior may adjust to keep the luminosity from exceeding this "Eddington limit". The mass limit is more of an empirical finding, no single star heavier than 80 solar masses has been verified. The problem may be one of stability-- you can get a solution that has higher mass, but it tends to erupt and blow off mass rather rapidly due to these instabilities. But lower metallicity stars are less subject to such instabilities because they have less opacity to block the light, and so you might expect much more massive stars in the first generation.