Galaxy Structure Evolution

Posted on October 1, 2014 by Takayuki Muranushi, Junko Kominami

I’ve heard about review paper by Dobbs & Baba on galaxy evolution.

Pattern speed of galactic arm is faster than the orbital speed of the stars. This is because bar (at the central) is dragging the pattern forwards. It is difficult to imagine a mechanism that makes the spiral slower than the stars.

Bar regions have large internal motions, which results in low optical depth.

As results of GMC mergers, Giant Mollecular Clouds of 10^6 Solar Mass is formed. Within it rapid Star formations takes place and lots of OB-stars are formed, out of Collision-induced star formation. Then, as results of SN explosions, GMC breaks up due to SN feedback.