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25

This was studied many years ago. Not only do galaxies have to hold together, but there also has to be enough matter to hold it tightly enough to spin at the speed it turns. (Imagine swinging an object on a string around your head, the faster it spins, the more force you have to apply.) (Note that galaxies don't actually rotate like a single solid object ...


37

The galaxy is kept together by the combined mass of the matter in the galaxy, of which the supermassive black hole is a negligible part. There are galaxies that don't have a central black hole (such as the Triangulum galaxy), but they are held together by their combined mass. In particular the dark matter of the galaxy is what provides most of the mass that ...


0

Although the question was asked a while ago, it still sounds interesting, so I did a bit re-search and I found a Nature news-feature by Adam Mann: Hidden history of the Milky Way revealed by extensive star maps The team had spotted a set of 30,000 renegade stars. Unlike other objects in the main body of the Milky Way, which orbit in a relatively flat disk ...


0

You'd be right to be a little suspicious if CHIME had just detected two events. Fortunately, that's not typically the detection criterion for a repeating FRB. In the case you're talking about, FRB 180814.J0422+73 (Amiri et al. 2019 for the CHIME/FRB Collaboration), six bursts were detected from one particular region, with only 18 total bursts detected in ...


2

I think there are a few misconceptions floating around here. The Hubble Sequence is not a sequence in time. Hubble did not mean to imply that galaxies flow from one side to the other in the sequence (He may have thought it was a possibility though). It is just meant for classification. As it turns out a small fraction of galaxies have changed class, ...


3

To start, if I'm reading your question correctly you've got the general galaxy evolution model backwards, at least as far as morphology goes. At a very high level the picture goes like this: most if not all (large) galaxies form as spirals, then at varying points in their lives they merge with other large galaxies (either ellipticals or other spirals) and ...


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