View Full Version : Discussion: How Do Large Galaxies Form?

2005-Jan-17, 06:43 PM
SUMMARY: Most large galaxies have the familiar spiral shaped disc surrounding a central bulge. But when and how do these galaxies take on their characteristic shape? New observations from the European Space Agency surveying 195 galaxies have given astronomers some clues. They've theorized that large galaxies go through a process called "spiral galaxy rebuilding", where galaxies collide, merge, and then begin a period of furious star formation. Part of the gas that didn't fall in rebuilds a disc around the galactic core creating a new spiral galaxy. This process could be repeated many times, building up the galaxy over billions of years.

View full article (http://www.universetoday.com/am/publish/how_large_galaxies_form.html)

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2005-Jan-17, 07:05 PM
That process seems plausible, but I don't think that the merger with another galaxy is necessary, if we also consider the mergers with infalling clouds of Hydrogen, either primordial clouds, or ones blown out of the galaxy earlier during its initial formation.

2005-Jan-17, 08:27 PM
I think that the more interesting finding is that this model still cannot account for the formation and characteristics of 25 percent of spiral galaxies. So it appears that the process of galaxy formation has more than one pathway to the end result.

2005-Jan-17, 10:13 PM
So, in other words, a galaxy recycles itself whenever a dwarf galaxy isn't nearby to engulf. That makes a bit of sense, but it just sounds like they're cramming all aspects of spiral galaxies together without any actual concept unification.

2005-Jan-17, 11:02 PM
The Collision Forming Theory makes some sense to me because of the recent findings of Chandra of the many, many Black Holes at Our Galaxy's Center. If there weren't collisions in the past, then I can't comprehend how that many Nova Remnants could have migrated to the Core of the Galaxy. In one Time Lapse Image over the last Maybe 3 Years there were no less than 12 Black Holes in rendom orbits around The Main Super-Massive Black Hole at the Galaxy's Center. The smallest of the 12 was estimated to be 300,000 Solar Masses, with as many as 20,000 additional additional Smaller Black Holes or Neutron Stars in the near Visinity. The agitation of the interaction of these bodies is kicking out the near-by stars which keeps any of them from feeding. Therefore, if there weren't coliding galaxies in the past, How did all of those 20,000 High Mass objects wind up at the center of Our Milky Way?