Stellar Structure

1.         From the fact that the average density of the Sun is near that of water, while the atmospheric density is very low, we may conclude that the interior of the Sun has a

a.         high mass

b.         high density*

c.         low temperature

d.         low density.

2.         Stars are spherical because of

a.         the high temperature in the interior

b.         their large size

c.         their hydrogen composition

d.         gravity*

e.         their nuclear energy generation.

3.         When you heat up a gas in a container, the

a.         density increases

b.         pressure increases *

c.         temperature decreases

d.         particles move more slowly

4.         If the interior temperature of a star decreases, the star will

a.         do nothing __________ that is, remain in the same

b.         contract*

c.         expand

d.         cease to exist as a star but cool off to become a planet.

5.         The fundamental quantity which determines a star's central pressure and temperature is

a.         mass*

b.         luminosity

c.         surface temperature

d.         chemical composition

e.         radius.

6.         The Russell-Vogt theorem states that the properties of a star at any given age depend completely upon the star's

a.         luminosity and radius

b.         mass and luminosity

c.         mass, chemical composition, and radius

d.         radius, and chemical composition

e.         mass and chemical composition.*

7.         Low mass stars burn hydrogen in the _______; massive stars burn hydrogen in the _______.

a.         proton-proton chain; proton-proton chain

b.         carbon-nitrogen-oxygen cycle; carbon-nitrogen-oxygen cycle

c.         proton-proton chain; carbon-nitrogen-oxygen cycle*

d.         carbon-nitrogen-oxygen cycle; proton-proton chain

e.         triple-alpha reaction; proton-proton chain.

8.         For stars like the Sun energy is transported by _____ in the core and by _____ in the envelope.

a.         radiation, radiation

b.         convection, radiation

c.         convection, convection

d.         radiation, convection*

9.         For massive stars, energy is transported by _____ in the core and by _____in the envelope.

a.         radiation, radiation

b.         convection, radiation*

c.         radiation, convection

d.         radiation, radiation.

10.      The lifetime of a star is determined by its initial

a.         temperature and luminosity

b.         temperature and radius

c.         temperature and mass

d.         mass and luminosity*

e.         mass and radius.

11.      Stars evolve because of changes in

a.         chemical composition of the core*

b.         luminosity of the star

c.         mass of the star

d.         chemical composition of the surface

e.         surface temperature.

12.      The evolution of stars in a binary system may differ from that of a single star because

a.         two stars are more massive than one star

b.         one star may transfer mass to the other*

c.         two stars have a higher combined temperature than single stars

d.         two stars have a higher luminosity than single stars.

13.      In a binary star system, the star loosing mass will evolve more ______, and the star gaining matter will evolve more ______.

a.         rapidly, rapidly

b.         rapidly, slowly

c.         slowly, slowly

d.         slowly, rapidly.*

14.      Which of the following is NOT a necessary ingredient in the construction of a theoretical star model?

a.         a balance between gravity and gas pressure

b.         a knowledge of the star's position and motion in space *

c.         a knowledge of the star's mass and chemical composition

d.         a balance between the star's luminosity and the amount of energy generated