HW#28: pg. 514 Rev 1 – 3, CST 1 – 3
Rev 1 – 3
1. Why don't stars live forever? Which stars live the longest?
2. How long can a star like the Sun keep burning hydrogen in its core? Why is the depletion of hydrogen in the core of a star such an important event?
3. Roughly how big (in AU) will the Sun become when it enters the red-giant phase?
CST 1 – 3
1. A star will evolve off the main sequence when it uses up (a) all of its hydrogen; (b) half of its hydrogen; (c) most of the hydrogen in the core; (d) all of its gas.
2. On the main sequence, massive stars (a) conserve their hydrogen fuel by burning helium; (b) burn their hydrogen fuel more rapidly than the Sun; (c) burn their fuel more slowly than the Sun; (d) evolve into stars like the Sun.
3. Compared to other stars on the H-R diagram, red-giant stars are so named because they are (a) cooler; (b) fainter; (c) denser; (d) younger.