Cypress College ASTR 116 Homework
Astronomy 116, Homework CHAPTER 12 (A) Stellar Evolution. Due:
Print Last, First Name and date on the small Scantron in INK. Print
your last name in BIG BLOCK letters on the back of the Scantron.
Use a No. 2 pencil to fill out Scantron. Read the chapter.
Look at the videos and simulations in the CD-ROM. Answer all True/False and
Fill in the Blank questions. Then answer the following questions
and turn in your Scantron only. Choose the best answer.
1. What is a planetary nebula?
- a) A planet surrounded by a glowing shell of gas.
- b) The disc of gas and dust surrounding a young star that will
soon form a solar system.
- c) The ejected envelope of a red giant surrounding a stellar core
remnant.
- d) A type of young, medium mass star.
2. Which statement is true, in terms of stellar evolution?
- a) Sooner or later, gravity loses.
- b) Sooner or later, gravity wins.
- c) Sometimes gravity wins and sometimes gravity loses.
- d) Gravity lets up under certain circumstances.
3. What event leads to the formation of a red giant?
- a) A contracting core of helium.
- b) Hydrogen shell burning.
- c) Expanding outer layers.
- d) all of the above
- e) none of the above
4. What characteristic of a star cluster is used to determine its age?
- a) The number of red giants.
- b) The faintest stars seen in the cluster.
- c) The main sequence turnoff.
- d) The total number of stars in the cluster.
5. Astronomers talk about "low-mass" and "high-mass" stars with regard
to their evolution. In units of solar masses, what is the dividing
line, that is, the lowest mass for a high-mass star?
- a) 2
- b) 4
- c) 8
- d) 12
- e) 20
6. The "helium flash" occurs at what stage in stellar evolution?
- a) in the middle of the main sequence stage
- b) red giant
- c) end of horizontal branch
- d) planetary nebula
- e) supergiant
7. What is the primary composition of a white dwarf?
- a) hydrogen
- b) helium
- c) carbon
- d) oxygen
- e) silicon
8. Which of the following best describes the evolutionary track followed
in the HR diagram for the most massive stars?
- a) Diagonally to lower right, then vertical, then horizontally
left
- b) Horizontally right, diagonally to lower left, then horizontally
right
- c) Horizontally right, then forms a clockwise loop
- d) Vertically up, then diagonally to lower right
- e) Horizontally right
9. In a star cluster, just as the most massive stars are evolving into
giants and supergiants, what is happening for the lowest mass stars?
- a) They continue to be main sequence stars.
- b) They, too, are evolving off the main sequence.
- c) Instead, they are evolving into white dwarfs.
- d) They are steadily gaining mass and moving up the main sequence.
- e) They are just starting to approach the zero-age main sequence.
10. Nearly all the elements found in our environment were formed inside
stars. The major exceptions are:
- a) Iron and nickel.
- b) Oxygen and carbon.
- c) Silver and technetium.
- d) Hydrogen and helium.