Chelsea Esposito's Quiz

Chelsea Esposito

1. What does our galaxy look like?
Our galaxy consists of a disk of stars and gas, with a bulge of stars at the center of the disk, surrounded by a
large spherical halo.

2. How do stars orbit in our galaxy?
Stars in the disk orbit in circles going in the same direction with a little up-and-down motion. Orbits of halo
and bulge stars have random orientations.

3. How is gas recycled in our galaxy?
Gas from dying stars mixes new elements into the interstellar medium, which slowly cools, making the
molecular clouds where stars form. Those stars will eventually return much of their matter to interstellar
space.

4. Where do stars tend to form in our galaxy?
Active star-forming regions contain molecular clouds, hot stars, and ionization nebulae. Much of the star
formation in our galaxy happens in the spiral arms.

5. What do halo stars tell us about our galaxy's history?
Halo stars are all old, with a smaller proportion of heavy elements than disk stars, indicating that the halo
formed first.

6. How did our galaxy form?
Our galaxy formed from a huge cloud of gas, with the halo stars forming first and the disk stars forming
later, after the gas settled into a spinning disk.

7. What lies in the center of our galaxy?
Orbits of stars near the center of our galaxy indicate that it contains a black hole with 4 million times the
mass of the Sun.

8. Who is Andrea M. Ghez?
She is an American astronomer and professor in the Department of Physics and Astronomy at UCLA. She
is known for the use of adaptive optics in studies of the galactic center.

9. Who observed stars moving close to the speed of light in the center of our galaxy?
Dr. Ghez

10. Where was Dr. Ghez born?
She was born in New York City, New York but grew up in Chicago.