Lives of Stars

Please get out your notes and a pencil

Nebulae

• Massive cloud of gas and dust

• Birth of new star

• Needs to be seen with infrared rays

Protostar

• The densest part of a nebula

• Contracting cloud of gas and dust with enough mass to form a star

A star is born when the contracting gas and dust from a nebula become so dense and hot that nuclear fusion starts.

nebula/protostar video

What is nuclear fusion???

Lifetimes of Stars

• How long a star lives depends on its mass.• Small stars live the longest• Large stars have a shorter life span.

• Our sun will burn for a total of around 10 billion years.

Deaths of Stars

• A star’s core shrinks and its outer layer expands becoming either a red giant or supergiant.

• After a star runs out of fuel, it becomes a white dwarf, a neutron star or a black hole.

White Dwarfs

• Outer layer of red giant drifts out into space forming a planetary nebula.

• Blue-white core is left, cools and becomes a white dwarf.

• Have no fuel left but glow from left over energy

• Once energy is gone it becomes a black dwarf.

Super Novas

• When a supergiant runs out of fuel, it explodes making the star a million times brighter.

• Material expelled by the explosion can become part of a nebula.

• Super Nova clip

Neutron Stars

• are the remains of high-mass stars.

• Spinning neutron stars are called pulsars, giving off pulses of radio waves.

Black Holes

• are an object with gravity so strong that nothing, not even light, can escape.• Gravity of the mass collapsing is so strong

that gas is pulled inward• No form of electromagnetic radiation can

escape a black hole• Scientists detect a black hole by looking at

the gasses around the phenomenon.