What is the mechanism thought to cause huge stellar nurseries to form e.g. eagle nebula?
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2$\begingroup$ any reason for the negative vote? $\endgroup$– Lucy MeadowCommented Aug 15, 2015 at 20:53
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1 Answer
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Molecular clouds are the most common places where stars are born, so it's best to discuss them.
Richard Larson (who has studied molecular clouds in depth) discusses two processes in an overview of these structures in The Evolution of Molecular Clouds:
- Random collisions between particles in the interstellar medium (ISM) grow over time until eventually larger structures appear. This takes much longer than the expected lifetimes of the component clouds, so it is an unlikely contributor.
- Large-scale instabilities cause gas to coalesce and collapse a little to form a molecular cloud. This growth theory takes place on smaller timescales, so it is a better bet for formation.
answered Aug 15, 2015 at 22:37
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$\begingroup$ Thank you HDE. I agree the 2nd one seems more plausible, given the lifespan (if that is correct). But I was wondering whether you found it convincing? It seems weak to me. I mean, those clouds are the most dense regions of space with up to thousands of times the mass of the solar system. $\endgroup$ Commented Aug 16, 2015 at 10:29
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$\begingroup$ @LucyMeadow I'm not an astrophysicist, so my opinion isn't that good. But while the clouds are dense in comparison to the ISM, they're still not dense when compared to other celestial bodies. $\endgroup$ Commented Aug 16, 2015 at 14:17
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$\begingroup$ True. But they are the densest regions of space (i.e. their size --> volume/mass $\endgroup$ Commented Aug 17, 2015 at 17:26
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$\begingroup$ HDE - do you think that due to being the densest part of the instellar medium, that these clouds have gravitation $\endgroup$ Commented Aug 17, 2015 at 21:25