AST 115 HW 13 Questions and Answers

Where are most heavy elements made? A) in the interstellar medium B) in stars and supernovae C) All were made in the Big Bang, when the universe first began. D) none of the above E) all of the above

B

Where do most dust grains form? A) in molecular clouds B) in the winds of red giant stars C) in supernovae D) in planetary nebulae E) all of the above

B

What is the thickness of the disk of the Milky Way? A) 1,000,000 light years B) 100,000 light years C) 1,000 light years D) 100 light years E) 10,000 light years

C

How does the interstellar medium obscure our view of most of the galaxy? A) Molecules in the interstellar medium absorb all wavelengths of light. B) Hydrogen gas produces so much visible light that the interstellar medium is opaque, blocking our view of anything beyond it. C) Dust reflects most light from distant regions of the galaxy back towards the source. D) The small mixture of dust grains in the interstellar medium absorbs visible light. E) all of the above

D

What elements do astronomers consider heavy elements? A) elements that are heavier than uranium B) elements that are heavier than hydrogen C) elements that are heavier than iron D) all elements besides hydrogen and helium E) elements that are heavier than carbon

D

What is the diameter of the disk of the Milky Way? A) 1,000 light years B) 10,000 light years C) 100 light years D) 100,000 light years E) 1,000,000 light years

D

Approximately how long does it take the Sun to orbit the center of the Milky Way Galaxy? A) 2 million years B) 20,000 years C) 2 billion years D) 200,000 years E) 200 million years

E

The star-gas-star cycle will continue forever because stars are continually recycling gas.

False

We can see most of the Milky Way with visible light.

False

All elements heavier than iron are made during supernova explosions.

True

Almost all elements heavier than hydrogen and helium were made inside stars.

True

Most of the mass of the Milky Way is located in the halo of the galaxy in the form of dark matter.

True

Observing our galaxy at radio wavelengths allows us to see through the dust in the disk that obscures our view.

True