What evidence do we have that the halo population of stars are older than other stars in the galaxy?
A) They are farther away.
B) They have higher masses than other stars in the galaxy.
C) They have fewer planets.
D) They have a smaller proportion of heavy elements.
E) They move slower than other stars in the galaxy.
Question 2
What is the ultimate fate of an open universe?
A) the Big Crunch
B) Stars will expand away from each other and galaxies effectively evaporate.
C) All matter decays to a low-density sea of photons and subatomic particles.
D) All matter eventually ends up in massive black holes.
E) Individual stars die but their gas is recycled through the interstellar medium and new stars form in a never-ending process.