For the following graph, I have some confusions:

  1. How do galaxies rank by mass? We know that on main-sequence, more luminous stars are also more massive, so I guess it also applies to galaxies.

  2. Do red sequence galaxies split into blue galaxies, or do blue galaxies merge into bigger red galaxies?

  3. Can galaxies ever be born as red sequence members? I doubt it because all galaxies should start from blue. But I am not 100% sure.

  4. Do red sequence galaxies tend to become redder over time?

  5. Do large galaxies use up star forming gas more rapidly than smaller galaxies?

color-luminosity chart for galaxies


closed as too broad by Sir Cumference, Hohmannfan, zephyr, Rory Alsop, Dieudonné Dec 12 '16 at 17:04

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ These are quite a few questions. I'd recommend dividing them up, and having this question focus on just one of them. $\endgroup$ – HDE 226868 Dec 11 '16 at 2:28