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Stars Have a Weight Limit
Mike writes "Using NASA's Hubble Space Telescope, astronomers made the first direct measurement within our Milky Way Galaxy, and concluded stars cannot get any larger than about 150 times the mass of our sun. The astronomers used the Hubble to probe the Arches cluster, the densest in our galaxy. This finding takes astronomers closer to understanding the complex star formation process. It also gives the strongest backing yet to the notion stars have a weight limit."
mass and weight- not the same thing.
Give a man fire, and you warm him for the night. Set a man on fire, and you warm him for the rest of his life.
Unfortunately, this is not a troll; this is true. It is a shame that we are going to lose something that has been so valuable to us when NASA decomissions it soon, despite that some say that ground based telescopes are good enough now. Good bye, Hubble.
You should look up the Nature article. The author himself is more cautious in the main text (c.f., his abstract says a bit firmly). And you will understand why the number 150 solar mass came about.
a) Lower limits are roughly 1/20 solar mass. Less mass than this can't product the temperatures and densities needed for hydrogen fusion.
b) roughly the population dies off as M^{-2.5}, with some hard cut-off at high and low mass. There are many more low- than high-mass stars.
c) Age goes roughly as M^{-3.5} or so. High mass stars don't live very long at all.
d) Yes! Not only energy output, but elemental abundance evolution. That was my thesis.
A better read than the ./ article reference is an article at hubble site.
What exactly do they consider direct versus indirect?
The article at hubblesite answers your question:
It will cost just as much to repair the Hubble as it would to put something else more compact and powerful out there, so troll or not, Hubble needs to make way for leaner and more powerful machinery.
I wouldn't mind Hubble dying if there were a replacement for it, but there isn't one. JWST isn't going to be active until 2011, and it is infrared-only.
TTFN
A white dwarf is the remnant from a low to mid-mass star (less than about 10 solar masses). White dwarves do not go supernova unless they have a very close binary companion that begins to dump mass onto its surface.
As a side note, white dwarf+companion supernova have characterstics in their spectra that are different from those of a single massive star collapse. As a result, they are distinguished by the labels Type Ia (for the WD binary SN) and Type II (for most single massive star SN), Ib, and Ic (for oddball stars that have been modified before the SN occurs). The labels are a bit strange because SN were classified by spectra before the explanation for the difference in their spectra existed.
Finally, although I'm not an expert in massive star formation, I think the 120-150 solar mass limit is not from a fast-burning argument, but from an argument that arises from looking at how such a massive system evolves dynamically in the early part of its life. Most massive stars have significant "winds" that slowly shed material from their envelops right from the start. It may be that such a process in stars with a chance to get larger end up disrupting the accretion process too fast.