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Star Smaller Than Some Planets Found

RobertFisher Re:Interesting... (138 comments)

You can show from basic stellar structure theory that you need a minimum mass of .08 solar masses or so to ignite hydrogen on the p-p cycle. (You can burn heavier isotopes like lithium and deterium at lower masses, but these contribute negligibly to the energy budget of the star because of their low abundances.) .08 solar masses is about 80 Jupiter masses, so this star is over the p-p burning limit. As another author pointed out, the star has a radius comparable to Jupiter. It turns out that due to the physics of degeneracy pressure. Jupiter is about at a maximum in radius for substellar objects.

more than 9 years ago

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Astrophysicists Explain Dimmest Supernovae Using Supercomputer Models

RobertFisher RobertFisher writes  |  about 2 years ago

RobertFisher writes "If thermonuclear supernovae are standard candles for cosmology, as the Nobel committee emphasized in 2011, all originating from the explosion of white dwarf stars, then why are some orders of magnitude dimmer than others? Recently, a group of astrophysicists (including myself) completed a large set of supercomputer models of these supernovae to uncover some peculiar cases which fail to detonate. These supernovae duds have remarkable properties, including the fact that the white dwarf gets kicked by the explosion but survives, and will go careening through the galaxy. This kind of exploratory science is only possible with the advent of petascale computing."
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New International Undergraduate-Level Physics Comp

RobertFisher RobertFisher writes  |  more than 3 years ago

RobertFisher (21116) writes "A new international undergraduate-level physics competition sponsored by the American Physical Society and the American Astronomical Society has been announced. Over the November 5th weekend, teams of three students will delve into a conceptually-rich an open-ended problem, with open access to books, journals, computer programs they've written, and the internet. The top 30% of all written reports will be recognized as either gold, silver, or bronze winners. This will be a ton of fun for any student interested in physics. Computer scientists have long had the ACSL contest, and mathematicians the Putnam competition. Why should they have all the fun?"
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