Life Cycle of a Star

1. Life Cycle of a Star By: Sara Ekern

2. Step 1 (high mass) In the densest part of a nebula gravity pulls gas and dust together with enough mass to form a protostar. A nebula is a large cloud of gas and dust in space.

3. Step 2 (high mass) After billions of years the star will eventually run out of nuclear fuel. The outer layers will expand and will become a high mass star then a super giant.

4. Step 3 (high mass) When the supergiant eventually runs out of fuel then explodes, the star shines a million times brighter than it did before and this is called a supernova.

5. Step 4 (high mass) Stars that have a mass more than ten times the mass of the sun will then create a black hole. After the enormous supernova explosion, more than five times the mass of the sun is left behind. The gravity of this mass is so strong that its gas is pulled in hard packing gas into a smaller space. The stars gas becomes squeezed so hard that it converts into a black hole.

6. Step 5 (high mass) After the supergiant explodes some of the material from the star left behind might convert into a neutron star.

7. Step 1 (low mass) In the densest part of a nebula gravity pulls gas and dust together with enough mass to form a protostar. A nebula is a large cloud of gas and dust in space.

8. Step 2 (low mass) After billions of years, the star will run out of nuclear fuel. The outer layers will end up expanding and they will become a red giant.

9. Bibliography • http://www.telescope.org/pparc/res8.html • http://en.wikipedia.org/wiki/Stellar_evolution • http://imagine.gsfc.nasa.gov/docs/teachers/lessons/xray_spectra/background-lifecycles.html

10. Step 3 (low mass) The outer layer of the star will still grow larger and drift into space forming a glowing cloud of gas called a planetary nebula.

11. Step 4 (low mass) The blue white core that remains of a red giant star is left behind and when it is fully cooled it is a white dwarf.