The Life Cycle of Stars

1. The Life Cycle of Stars Mike Chris

2. Life of a Small to Medium-Mass Star

3. Nebulas And Protostars • Stars begin as a nebula, or clouds scattered dust made mostly of hydrogen • As the nebula collapses the contents of it begin to to heat up. This is known as a protostar • This phase can be referred to as the fetus of the star http://www.godandscience.org/images/nebula.jpg

4. Brown Dwarf • Brown dwarfs are objects in space • They are not technically stars, and are bigger than planets Brown Dwarf http://seanf.hypexr.org/project/Brown_Dwarf.jpg

5. MainSequence • The main sequence is where stars live most of their lives • Right now, our sun is in the main sequence • A star begins the main sequence when nuclear fusion begins Main Sequence Star http://www.noaanews.noaa.gov/stories2005/images/sun-soho011905-1919z.jpg

6. Fusion Nuclear fusion is when two atoms combine to make a larger one In stars this is between hydrogen and helium When a star runs out of hydrogen, it starts fusing helium and carbon Larger stars can fuse carbon into even heavier elements like iron

7. Red Giants • When a star starts burning helium, it starts to pack the atoms tighter together, causing the outside of the star to expand • When this happens, it is classified as a red giant • This is the first step into old age Red Giant http://www.lancs.ac.uk/ug/hilditch/pic3.gif

8. Planetary Nebula • Planetary nebula is a nebula that has gas and plasma • Planetary nebulas are made of dead stars • After a red giant a planetary nebula is made Planetary Nebula http://en.wikipedia.org/wiki/File:NGC6543.jpg

9. White and Black Dwarfs • The cores of low-mass stars are white dwarfs • White dwarfs are close to the size of the Earth, but may weigh as much as our sun • They are not as bright as larger stars • White dwarfs are very bright because of the heat made when the star collapsed • A black dwarf is made when white dwarf becomes cold • Black have not been proven to exist because it takes longer for a white dwarf to become one than the universe has been in existence White Dwarf http://cactus.dixie.edu/smblack/chem1010/images/Unit_4/4A_white_dwarf_star.jpg

10. Life of a High-Mass Star

11. Massive Main Sequence • Massive main sequence stars are the same as small or medium-mass except that they are bigger so they burn hydrogen faster Massive Main Sequence Star https://segue.atlas.uiuc.edu/uploads/ryemm2/blue%20main%20sequence.jpg

12. Supergiant • Supergiants are the largest stars in our universe • They can have a diameter of around 1,000 times bigger than our sun Supergiant http://isc.astro.cornell.edu/~sloan/fun/figures/star_agb.gif

13. Supernova • A supernova is an explosion of a high-mass stars • This happens when a star’s supply of energy and light runs out • This only happens every few millions of years Supernova Remnant E0102-72 http://imagine.gsfc.nasa.gov/Images/bios/stecker/large.supernova.jpg

14. Neutron Star A neutron star is the result of a supernova A neutron star is small and dense and is mostly made up of neutrons , hence the name A neutron star is bigger in mass than our sun http://nrumiano.free.fr/Images/Neutron_star_E.gif

15. Black Holes A black hole is another result of a supernova It is a thing in space that has such a strong pull of gravity so strongly that light can’t be seen Until recently, astronomers didn’t know that black holes even existed because black holes can’t be seen with a telescope Black Hole http://ucsdnews.ucsd.edu/graphics/images/2006/neutron-star-jet_bg.jpg

16. Why high-mass and low-mass stars live different lives • High-mass and low-mass stars take different paths at the end of their lives • High mass stars burn their fuel faster than low-mass stars, which is why low-mass star live much longer than high-mass stars • Also, high mass stars end their lives with a supernova, then a black hole or a neutron star • Low mass stars end their lives by becoming a white dwarf Black Hole http://www.geosociety.org/graphics/04denver/blackhole.jpg

17. Ages of Different Mass Stars Most massive-20 million years Our sun-10 billion years Least massive-1 trillion years http://www.keyway2.ca/jpg/stars.jpg

18. Sites • http://nasascience.nasa.gov/astrophysics/how-do-stars-form-and-evolvehttp://sunshine.chpc.utah.edu/labs/star_life/starlife_main.htmlhttp://simple.wikipedia.org/wiki/Supergiant • http://simple.wikipedia.org/wiki/White_dwarf • http://simple.wikipedia.org/wiki/Red_giant • http://simple.wikipedia.org/wiki/Black_hole • http://simple.wikipedia.org/wiki/Main_sequence • http://simple.wikipedia.org/wiki/Neutron_star