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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

T. Tauri

Stars that emerge from the cocoon (protostars are embedded in a cocoon which makes them hard to observe)

Top Right

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

radiative heat

Inner 2/3 of sun

Convective heat

Outer 1/3 of sun


Energy transport varies with ____ of star

less than

Fusion will not begin if mass is _____________ 0.08 M* (Mass of sun)

Brown Dwarf

Protostar not massive enough to ignite fusion

90%, mass

Stars spend _____ of their live on the main sequence. The time on Main sequence depends on _______.

10, 10

Sun (1M*) = ___ billion years (1 x 10 ^__ years; 1 solar lifetime)

T=1/M^2.5 (1x10^10)

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

1 billion

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 ____.

Variable stars

Stars that change brightness rapidly and periodically

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