Chapter 13 Flashcards
gravity can create stars only if..
it can overcome the force of thermal pressure in a cloud
gravity within a contracting gas cloud becomes stronger as the gas what?
becomes denser
gravity is working against what?
gravitational contraction and nuclear fusion and degeneracy pressure
a cluster of many stars can of be formed out of what?
a single cloud
dust grains heat up and emit _______ light
infrared
rotation causes _____ of matter to shoot out along the rotation axis of ______
protostars (still in the process of forming)
_______ ends when energy released by hydrogen fusion ____ energy radiated from the surface
Contraction
fusion
a ______ contracts and heats until the core temperature is sufficient for hydrogen fusion
protostar
it took the sun _____ years, to change from protosar to main sequence
30 million years (less time for more massive stars)
gravity causes ______ and _______ cloud to shrink
cold and dense cloud
when the core gets hot enough, ____ begins and stops the shrinking
fusion
what are brown dwarfs?
starlike objects not massive enough to start fussion
______________ halts the contraction of objects (brown dwarfs) before the temperature becomes hot enough for fusion
Degeneracy Pressure
what would happen to stars more massive than 300MSun?
would blow apart
what happens to stars less massive than 0.08Msun?
they cant sustain fusion