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10 Cards in this Set

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Stage 1: Interstellar Cloud

-begins with a cold dark dust/gas cloud made up of atomic and molecular gas


-an eternal event triggers the collapse of the cloud


-gravitational instabilities fragment the cloud into 10-1000s of fragments

Stage 2: Collapsing Cloud Fragments

-a sun star requires a fragment cloud containing 1-2 solar masses of H gas and dust


-fragments are expected to be 100 times bigger than the diameter of our solar system

Stage 3: Fragmentation Ceases

-fragments shrunk to the size of our solar systems


-cloud edges become cold, transparent, and radiate out heat


-gases continue to be pulled to the centre


-now known as a Protostar

Stage 4: Protostar

-begins to evolve and shrinks, while density and temp increases


-brighter than main sequence stars


-100x the radius of the sun


-once it becomes a hydrogen

Stage 5: Protostellar Evolution

The Hayashi Track: the protostar approaches the main sequence it shrinks to 10x the size of the sun and losses luminosity to 10x that of the sun

Stage 6: A New Born Star

-stars has contracted and internal temp has increased to 10000000k and nuclear fusion starts to occur


-surface temp is 4500k

Stage 7: Main Sequence Star

-contracts a little more, central temp: 15000000k


-nuclear fusion is in full swing


-surface temp 6000k


-outward pressures of fusion and inward pressures of gravity are balanced


-much like our sun it will stay in this phase for 10 billion years

Process Timing

-takes 40 to 50 million years for the whole process (this is equivalent to 1% of our suns life time)

Mass of Cloud and Star Formation

-the time required for star formation is strongly correlated to the mass of the cloud


-the most massive clouds become main sequence O stars (big and blue) in 1 million years

Shockwaves and Star Formation

Sources:


1. star formation


2. death of a star


a) ejections of gas shells (red giants)


b) supernova


3. density spiral arms


4. gravitational interactions between galaxies