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Topic 10
Nebula- where stars form
-gas and dust
Protostars- baby stars
Most nebula is
invisible unless bright stars nearby shine on gas and dust- called diffuse
nebula.
Dark nebula-shows up as a darkpatch
against a background of star.
When hydrogen is fused into helium gas in the
center of a star, a star is born. This causes
huge amounts of energy. When the release
of energy counterbalances the force of gravity, the star stops contracting and
becomes a stable state star.
Our sun is a stable state star, at least 5
billion years old and is expected to remain stable for the next 5 billion years
then expand out into a red-giant.
Topic 11 Red giants
When there is no longer any fuel left in the
core of the star, the star is not stable and it contracts, it gets very hot, then stars to expand into a red giant.
Topic 12 White Dwarfs
When the fuel of fusion is used up the giant
collapses into a white dwarf star.
If a white dwarf flairs up this is called a
nova. Our sun is expected to go through
this stage as well.
Whit dwarfs form from stars about the same mass
as our sun.
Topic 13 Supernovas
A star will become a red giant relatively
quickly if the star is very large- called a super giant
Super red giants may become a supernova
explosion as the star cools, core-collapses causing star to violently explode.
½ of a stars mass may
blow away- Supernova explosion.
Chinese observed supernova explosion in 1054
A.D.
The outer shell of star located in Crab Nebula- Constellation
Taurus the Bull
Best record before modern times.
Most famous supernova explosion in modern times occurred
in the Large Magellanic Clous
and was visible in 1987.
Topic 14 Newtron Stars and Black Holes
The mass that remains after a supernova
explosion is called a newtron star
10km in diameter but trillions of times more
dense than our sun
Black holes: End point of a star. Star is crushed into a single point.
Region in space where sp much mass is concentrated,
that no objects can escape.
First suspected was a strong X-ray source in the
constellation Cygnus x-1.
Based indirect evidence.