2015年2月28日 · There is enough energy released by gravitational collapse to heat the Sun to its current temperature. You can do a more detailed analysis taking into account how much cooling occurs during the collapse, but the steep temperature dependence of the Stephan-Boltzmann law makes it difficult to lose heat to space until the object is already hot.

2024年7月2日 · However, this involves a loss of energy to the environment and hence an overall increase in the entropy of the Universe. This crucial detail always seems to be missing from discussions of the Jeans mass and gravitational collapse. I was wondering if there are any nice, simplified models of this that can be easily expressed?

2019年1月10日 · The answers to Gravitational collapse and free fall time (spherical, pressure-free) describe the calculation of collapse time for a gas. For the case of neutral hydrogen gas with number density $10...

2016年3月11日 · Gravitational collapse is a fundamental mechanism for structure formation in the universe. Over time an initial relatively smooth distribution of matter will collapse to form pockets of higher density, typically creating a hierarchy of condensed structures such as clusters of galaxies, stellar groups, stars and planets.

A partial answer only. Given a spherical collapse, and ignoring relativistic effects, the time is the same as the time taken for a particle at the edge of the cloud to fall to the centre.

2017年4月23日 · "at the instant of gravitational collapse" Remember that gravitation propagates at the speed of light, so even if anything where going to happen (it won't) it takes time for the information to get out to the planets. "Assuming this sudden change would cause some perturbation" It won't, so we don't assume that, which also disposes of your fourth ...

2021年1月1日 · You can only have a gravitational collapse if the gas cloud continuously loses energy through inelastic collisions (which is then radiated off). Otherwise the collapse would soon come to a halt as the lost potential energy would be turned into kinetic energy and a steady state would be reached once the kinetic energy is -1/2 x the potential ...

2016年5月4日 · During gravitational collapse, gravitational potential energy of the gas is converted to its internal kinetic energy so the internal energy of the cloud of gas is said to be increased. Like CuriousOne said, this depends on how you define the internal energy of the cloud.

$\begingroup$ I initially upvoted this, but now see it is incomplete and contains several inaccuracies. e.g. The collapse is faster in the inner regions, not the outer regions; why would splitting Fe and making more particles "reduce the core's mass and the pressure", this doesn;t make sense; the Fe has already decomposed by the time you get a core bounce, you need …

2021年5月24日 · After a star becomes a White dwarf, it resists gravitational collapse mainly due to the electron degeneracy pressure. If the mass of the white dwarf is greater than the Chandrasekhar limit, the degeneracy pressure cannot resist the collapse any longer and is doomed to become a neutron star or a black hole.