ASTR 220 - Collisions in Space
Homework 4 (12 points)
Due Tuesday December 7 at the beginning of class
- Describe what happens when one member of a binary star system
evolves to the point that it fills its Roche lobe.
- Are galaxies spread homogeneously through space? Describe the
large scale structures traced out by galaxies.
- What evidence suggests that supermassive black holes exist
at the centers of galaxies?
- Below is a picture of the spiral galaxy M101.
- a) Judging from the size of the bulge and the shape of the
spiral arms, is this likely to be classified as an Sa
or an Sc galaxy? Briefly describe why.
- b) The color of this galaxy changes gradually from red to blue
as one moves outward from the center. Given what you know about the
evolution of stars, what does this color gradient imply about the average
ages of stars at different radii?
- c) Stars form together in clumps. Do you see any evidence for recent
star formation in this image? Where?
