The birth of stars begins with contraction & heating of interstellar matter initiated by ______.
Exploding stars that produce shock waves
As gravity draws atoms together, temperature ____.
Collapsing cloud of gas & dust
Protostars radiate ____ radiation, which is invisible to the eye
Stars that emerge from the cocoon (protostars are embedded in a cocoon which makes them hard to observe)
Protostars are found at the ____ _____ of the H R diagram, shift down & to the left when fusion begins
For a main sequence star, the H --> He. Protostar stage ends when ____ begins.
Sun took ____ million years to reach the main sequence star stage
In Nuclear fusion, Mas --> _______
For nuclei to fuse, they must be _____ together
Hydrostatic Equilibrium, collapsing star, expanding star
In ___________ __________, the Force of gravity (________ ______) is offset by pressure (__________ _____)
Type of heat not important in stars
Inner 2/3 of sun
Outer 1/3 of sun
Energy transport varies with ____ of star
Fusion will not begin if mass is _____________ 0.08 M* (Mass of sun)
Protostar not massive enough to ignite fusion
Stars spend _____ of their live on the main sequence. The time on Main sequence depends on _______.
Sun (1M*) = ___ billion years (1 x 10 ^__ years; 1 solar lifetime)
Life expectancy of stars
He, H, H
Post Main Sequence stars, ____ accumulates in the core. The ___ outside the core heats up, ignites as a shell of fusing ___.
Excess energy causes outer layers of a star to ____
Triple Alpha Process
Helium fusion begins in core
The sun will last _______ years as a giant
C, O, Ne, Si
Fusion of __, __, __, and ___ can occur later in massive stars
When usable fuel is exhausted, all stars will ____.
Stars that change brightness rapidly and periodically