Sister blog of Physicists of the Caribbean. Shorter, more focused posts specialising in astronomy and data visualisation.
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Red, dead, but very well-fed
What stops galaxies from forming stars ? Normally I'm most interested in this for objects which have hardly any stars at all : ultra dif...
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In the last batch of simulations, we dropped a long gas stream into the gravitational potential of a cluster to see if it would get torn...
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Of course you can prove a negative. In one sense this can be the easiest thing in the world : your theory predicts something which doesn...
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Another day, another paper on how exciting Ultra Diffuse Galaxies are. At first, these large, faint galaxies were just wholly unexpected, a...
MHD?
ReplyDeleteWhy didn't it collapse gravitationally and how did it start off as a sphere? Sound waves might play a role as well.
ReplyDeleteLocally, parts of the gas do collapse and form those little dense blobs that fly off. But the sphere as a whole has too much energy - each section of the cloud is moving at greater than the overall escape velocity, so it's doomed to explode. Since the velocity field is complicated, parts of the cloud collide with each other, forming locally gravitationally bound substructures.
ReplyDeletePressure waves are probably important for the small structures, but probably not for the overall cloud. Sound speed is equivalent to a crossing time of about 200 Myr, a bit longer than what's shown here.
Rhys Taylor Pressure is a measure of the kinetic energy density so you've given it an initial pressure, in some sense.
ReplyDeleteIs this simulation Eulerian or Lagrangian?