In class we learned about two main different types of galaxies:
spiral and elliptical. The formation of these two galaxies is distinct, spiral
galaxies form from quantum fluctuations and inflation leading to overdensities
and seed galaxies. In these seed galaxies, normal matter collapses and begins
to spin according to the conservation of angular momentum. Elliptical galaxies
form due to mergers between galaxies leading to the randomization of orbits of
stars, leading to a ball-shaped galaxy with random orbits of stars. However, we
did not discuss any irregular galaxies. One interesting irregular galaxy type
is known as a ring galaxy.
A ring
galaxy is a galaxy with a circle-like appearance. A classic example of a ring
galaxy is Hoag’s Object, discovered by Art Hoag in 1950. When he discovered the
object, Hoag initially thought that the visible ring was a product of gravitational
lensing. However, this idea was later discarded because the nucleus and ring have
the same redshift. There have been many additional ring galaxies discovered
since Hoag’s discovery.
http://www.universetoday.com/30697/ring-galaxy/
http://www.redorbit.com/education/reference_library/space_1/universe/2574754/ring_galaxy/
http://en.wikipedia.org/wiki/Ring_galaxy
http://ned.ipac.caltech.edu/level5/Sept01/Appleton/frames.html
I continued to be fascinated by the myriad aspects of our universe that we know so little about. I truly appreciate that you chose to write of a topic we have not spent much time discussing. The Ring Galaxy is an extremely interesting type of galaxy that can be found within our universe. What I find most interesting about your post is that we know these galaxies exist yet we know very little of how they are formed. I must be honest, it is difficult for me to accept something like this without knowing how it becomes itself. Does anyone else find this a difficult concept to grasp? However, then I think of other aspects of our universe such as gravity that we knew existed but initially not how it existed. Like gravity, I believe the Ring Galaxy's formation will present itself as some point in our future but for now they are fun to look at and learn what we do know.
ReplyDeleteI find irregular galaxies very interesting. The fact that the disk and elliptical shapes are the most stable tell us a great deal about gravity and its effects on the movement of matter in the universe. However, the fact that some irregular galaxies, such as ring galaxies, are able to sustain themselves at least for a relatively short time indicates that there is always the possibility for multiple forms of stability. These irregular galaxies usually evolve into either disk or elliptical galaxies over time, showing us that these forms are the most stable in our universe.
ReplyDeleteIrregular galaxies are interesting because we don't know very much about them. I think that our perspective of the plane that we see them in makes us see them in a variety of different ways. The short lived lives of the ringed galaxies suggests that a lot of energy is at work in these systems. What fascinates me is the central star bulge caused by the compression of the galaxy. It would be very fascinating to catch two galaxies while they begin to collide with each other because then we would gain valuable information of what we can expect with our own galaxy.
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