Author Question: How do we know that halo stars are older, on average, than disk stars? A) Halo stars orbit in ... (Read 160 times)

deesands · **on:** Jul 27, 2018

How do we know that halo stars are older, on average, than disk stars?

A) Halo stars orbit in random directions but disk stars have more ordered orbits.
B) There are no blue halo stars.
C) There are no red disk stars.
D) Theories of galaxy formation tell us that the halo formed earlier than the disk.
E) We see evidence for new stars forming in the disk today.

Question 2

Which of the following are candidates for dark matter?

A) brown dwarfs
B) Jupiter-size objects
C) WIMPs
D) faint red stars
E) all of the above