Use these questions to test your understanding. If you get them wrong, you will be linked back to the relevant part of the notes.
Be sure you study them thoroughly (don't just get a quick fix for your mistake) so your overall understanding is improved.
1. The best place to look for stars just beginning to form is
a. in empty space b. in a molecular cloud
2. Which physical force dominates the process of star formation?
a. strong nuclear b. weak nuclear c. electrical d. gravitational e. reactional
3. Disks form around young stars
a. if the cloud from which the star forms is too massive for all of it to fall into the star
b. when the new star passes through a dense cloud and it is attracted to the star
c. from material that was spinning around the protostellar core too fast to fall into the star
d. when a second star that formed in orbit breaks up
e. disks are something that only form around older stars
4. To form a real star, an object must be massive enough to
a. have enough gravity to hold planets in orbit
d. create enough pressure and heat in its core for hydrogen fusion
e. burn hydrogen and helium into heavier elements
5. Star formation is often aided by
a. planets passing through a molecular cloud and upsetting its equilibrium
b. a gravitational vibration caused by thermal instability in interstellar gas
c. a supernova explosion near a molecular cloud that compresses it and starts fragments collapsing
d. heating of an interstellar cloud by a nearby young star
e. centrifugal forces caused by spinning cloud fragments
6. A very large clump of interstellar matter
b. can make a star up to nearly any mass range
c. takes an extra-strong initial event to start it collapsing
d. collapses into a star particularly slowly because it is so big
e. can explode as a supernova rather than becoming a star
7. Clumps of matter with too little mass to form stars
a. seldom collapse - they just stay part of the interstellar medium
b. usually join together to form stars
8. When clumps first collapse into young stars,
a. they cannot burn hydrogen because it has not settled into their cores yet
b. they cannot burn hydrogen until a spark ignites it
c. their activity level needs to rise before they can burn hydrogen
d. their cores must shrink and heat up to burn hydrogen
e. the hydrogen must be converted from molecular to atomis form to burn