 Star Formation
Star Formation
The following
are the reasons where and why stars form:
Stars form in dark clouds dusty gas in
interstellar space, in between what is called
InterStellar MediumWe determine
composition of ISM from its absorption
lines70%H, 28%He, 2% Heavier
ElementsSome pockets are cool & dense
where stars form, while others are some are hot and
less denseThe cool, dense parts are the
areas where it is cool enough to form molecular
clouds made up of H2, CO, NH3, etc.1% of
molecular clouds are made of dustStars
form as a result of tempering thermal pressure with
gravity where gravity has upper
handContraction of the gas/dust cloud
converts gravitational potential energy into
thermal energyIf excess thermal energy not
gotten rid of, pressure would increase and
contraction would come to a haltEmission
lines from molecules in a cloud can prevent a
pressure buildup by converting thermal energy into
infrared and radio photonsFragmentation of
the molecular cloud - growing strength of
gravity over pressure in dense lumps fragment the
cloud, and each lump can go on to form one or
moreIsolated star formation -
gravity can overcome pressure in relatively small
cloud if the cloud is unusually
denseTrapping of thermal energy -
Gravity packs molecules and dust particles of a
cloud fragment close together, which makes it
harder for infrared and radio photons to
escapeThermal energy builds up, increasing
internal pressureContraction slows down,
and center of cloud fragment becomes a
protostarGrowth of a protostar
and blowing off the remaining gas: Matter from
the cloud continues to fall onto the protostar
until the protostar blows the surrounding gas away,
likely via stellar windPosted 18:08
|
share!
