Quote:
Originally Posted by Glitch
I had not thought of that. Something like a small piece of Dark Matter gets stripped off of one or both colliding galaxies, which collects dust and gas over time. That seems like a very reasonable explanation.
The reason these galaxies are green in appearance is because they are primarily made from ionized oxygen (O III) gas. If they collected gas and dust after a collision, I would think that the composition of the gas collected in this manner would be more random, but maybe not. I certainly do not have a better explanation.
I know the link to the paper I posted suggests that these Green Pea galaxies may have helped the reionization process, but that would make them ~13 billion years old. In which case would we not see lots of older Population II and III stars (F, G, K, and M types) in addition to the newer stars? In other words, several generations of stars should have formed and died in these galaxies. The observations suggest that these are fairly new galaxies, which could also explain why they are producing 3.25 more stars per year than our own Milky Way galaxy even though they are only about one tenth the size. Newly formed galaxies should be gas rich, unlike elliptical galaxies like IC 1101 which are practically void of gas and therefore have little or no new star formation.
I love this kind of scientific speculation. Eventually they will work up postulates, then an hypothesis, and that will eventually lead to a theory.  |
The impression I got is that the Green Peas could possibly help with better understanding the reionization process, but not necessarily that they should be as old as ~13 billion years. Galactic collisions can produce some pretty chaotic conditions. It may be such conditions allow for the reionization process to occur, particularly with O III present in a newly forming mini-galaxy. There can't be many stars in the Green peas as it is. Mostly gas, Dark Matter with gravitational attraction binding and holding it together.
I agree with you that a galactic collision could well disrupt the Dark Matter of the colliding galaxies, scattering it around (like the spash when you throw a rock in the water), some of which untimately becomes part of the new Pea galaxies, as well as larger amounts settling down to surround the host galaxy. I don't think it would take a collision forceful enough to tear a galaxy completely apart. Even a smaller collision could cause enough disruption to fragment material like Dark Matter at the point of impact.
I've generally thought of our galaxy as being pretty large, and it is. Really? Somehow I'm not so sure I'll ever be able to think of it again as being so large. It's really tiny compared to IC 1101.
Speaking of the smallest galaxies, there was a live feed on YouTube about the most light-weight galaxy yet discovered. It's a tiny dwarf galaxy called "Segue 2". Unfortunately, I was only able to catch the last 10 minutes or so of it. But I did find a recent link, dated June 10, describing it.
Lightweight Galaxy Is the Smallest Ever Found | Segue 2 | Space.com
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