Is life more likely to be present in spiral galaxies or in elliptical galaxies?
It is true that elliptical galaxies are dominated by the oldest populations of stars in the universe, and are therefore intrinsically very poor in the heavy elements needed to form planetary bodies. Spiral galaxies, however, contain very young ‘metal rich’ populations of stars that could more easily provide the elements needed for life. But, some elliptical galaxies may ‘canibalize’ their element-rich neighbors and so acquire stars and gas that can form planets, or may already have done so. There is also another issue. We think that all stars, regardless of their heavy element compliment, have to have emerged from some kind of rotating disk of gas with the central parts forming the star itself. If we estimate that 10 percent of the mass of the star is in such a disk, the typical stars in elliptical galaxies have masses from 1 – 0.5 times that of the Sun, and their heavy element compliment is about 100 times lower than for the Sun. A little arithmetic shows that the amount of heavy elem
Related Questions
- Can you arrange the following galaxies in order of decreasing size: spiral, giant elliptical, swarf elliptical, irregular?
- Is there other evidence that Type Ias in elliptical galaxies are different from those in spiral galaxies?
- Do galaxies have life cycles as stars do? Will all spiral galaxies eventually become ellipticals?
