Life Cycle of Stars Not All Stars are

Life Cycle of Stars

Not All Stars are the Same • We will examine the following stages of life for stars: ▫ Birth ▫ Early life ▫ Major part of life ▫ Old age ▫ Death ▫ Remains • The results of each stage will be different for each star depending on its mass

A Star is Born! A star is born from a cloud of dust and gas called a nebula Nebula means “mist” in Latin

Early Life A small star (like our Sun) will gradually turn into a hot, dense clump that begins to produce energy. This happens when parts of nebulas collapse in on themselves Gravity and mass will increase causing a tightly packed sphere of matter to form Eventually the pressure gets so high that nuclear fusion occurs

The Major Part of Life The star really turns “on” when nuclear fusion starts transforming Hydrogen into Helium This produces energy (light & heat) The Star stays in this for most its life state The length of aofstar’s life depends on its mass and how quickly it uses up its Hydrogen For a star similar to our Sun, it will use nuclear fusion to produce energy for about 10 billion years

Old Age After a while, all of the hydrogen in the core of the star gets used up Helium is then used for nuclear fusion The core starts to collapse and the outer layers of the star expand

Red Giant As the outer layers expand, the star becomes a large, cool red giant See the size difference between the Sun and a Red Giant

Death Outer layers of the Red Giant drift away The core shrinks The star becomes a small, hot, dense white dwarf star Sirius (Dog Star) Sirius B – White Dwarf Remains The white dwarf star will eventually cool off, and fade away

Life of Bigger Stars For stars 10 times the size of the Sun: In a short time will become a hot dense clump, and use nuclear fusion to produce energy Only uses nuclear fusion for a few million years They are 5000 times brighter than the Sun For stars 30 times the size of the Sun: In a very short time will become a hot dense clump, and use nuclear fusion to produce large amounts of energy Only uses nuclear fusion for about one million years They are extremely bright

Old Age Larger stars swell to become Red Supergiants Red Supergiant

Death of Bigger Stars Bigger stars have a more extravagant death Their cores collapse inwards, sending the outer layers exploding into a supernova

Remains of Bigger Stars that are around 10 times the size of the Sun will turn into a neutron star after the supernova. Gases from a neutron star drift off as nebula and get recycled

Black Holes The largest of stars will end up as black holes http: //hubblesite. org/explore_astronomy/black_holes/i ndex. html

Eagle Nebula

Heart Nebula

Fairy Nebula