Life of stars -

Life of Stars
By: Hannah Angela G. Dy Guaso
Kristen Zakaya C. Zarate
What stars are
• Huge sphere of hot gas
• Produce own light and energy by nuclear fusion.
• Fusion happens when lighter elements are forced
to become heavier elements.
• Energy is created causing the star to heat up and
Clouds of gas and dust
are disturbed by the
gravity of a nearby
The disturbance causes
clumps to form and draw
gas inwards
The collapsing clump
begins to rotate and
flatten into a disc of gas
and dust.
The disc rotates faster and
faster pulling more
material inwards creating
a hot, dense core called a
When the protostar
becomes hot enough
hydrogen atoms begin
to fuse, producing
helium and energy
After millions of years a
bipolar flow erupts from
the protostar and blasts
away remaining gas and
Lifespan of stars
• mass of star defines its lifespan.
• least massive stars live longest
• most massive stars in the Universe use fuel up
in a few million years
• biggest stars last only millions
• medium-sized stars last billions
• smallest stars can last trillions of years.
How stars die
1. Helium fuel runs out
2. core will expand and cool
3. Upper layers will expand and eject material that
will collect around the dying star to form a planetary
4. core will cool into a white dwarf and then
eventually into a black dwarf.

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