by cabellasus » Tue May 03, 2011 6:38 pm
It is difficult to seriously consider this in the absence of any compelling theory describing how globular clusters formed. My own view is that disc-like rotating systems are a special case, and occur when a rotating system forms under viscous conditions that favor a single axis for angular momentum. But in lower density systems, there is no reason to expect disc formation, and in the long term I expect disc-like systems to evolve to elliptical and ultimately spherical systems. Globular clusters are currently in high entropy states, and I see no mechanism to lower that entropy and produce a more ordered or symmetrical structure.
Ah, so I'm not crazy. There "is no compelling theory describing how globular clusters form" ???
Mentally, certainly, i cannot picture how globular clusters OR spherical galaxies form, if they form by accretion (and not capture, which g.c.'s certainly do not, given relative uniformity of star types/ages). Picture a sphere of randomly moving particles. How would they accrete? And when they did, there would be coalescence into non-random flows, giving a predominate vector or vectors. IOW, i can only picture accretion occuring in a disc (relatively two-dimensional) despite being in three dimensions (or more, granted).
One must admit, that if a
planetary system was spherical, without an ecliptic
plane , and whose planets had random orbits, then astronomers would argue it formed by capture, not accretion. Right? So how the h*ll do they explain globular clusters or galaxies, the former with matching (not random) stars, so to speak???
[quote] [b]It is difficult to seriously consider this in the absence of any compelling theory describing how globular clusters formed[/b]. My own view is that disc-like rotating systems are a special case, and occur when a rotating system forms under viscous conditions that favor a single axis for angular momentum. But in lower density systems, there is no reason to expect disc formation, and in the long term I expect disc-like systems to evolve to elliptical and ultimately spherical systems. Globular clusters are currently in high entropy states, and I see no mechanism to lower that entropy and produce a more ordered or symmetrical structure.[/quote]
Ah, so I'm not crazy. There "is no compelling theory describing how globular clusters form" ???
Mentally, certainly, i cannot picture how globular clusters OR spherical galaxies form, if they form by accretion (and not capture, which g.c.'s certainly do not, given relative uniformity of star types/ages). Picture a sphere of randomly moving particles. How would they accrete? And when they did, there would be coalescence into non-random flows, giving a predominate vector or vectors. IOW, i can only picture accretion occuring in a disc (relatively two-dimensional) despite being in three dimensions (or more, granted).
One must admit, that if a [i]planetary system was spherical[/i], without an ecliptic[i] plane [/i], and whose planets had random orbits, then astronomers would argue it formed by capture, not accretion. Right? So how the h*ll do they explain globular clusters or galaxies, the former with matching (not random) stars, so to speak???