Lifecycle of a Star

1. Picture: http://upload.wikimedia.org/wikipedia/commons/4/4e/Pleiades_large.jpg Lifecycle of a Star The Pleiades Star Cluster Low and High Mass Stars By Zairamink

2. Low Mass Stars Picture: http://en.wikipedia.org/wiki/File:Orion_Nebula_-_Hubble_2006_mosaic_18000.jpg Orion Nebula A Star of Lower Mass

3. Low Mass Stars, Stage 1: Interstellar Gas Cloud Info: http://library.thinkquest.org/3103/nonshocked/topics/interstellar/interstellar.html Picture: http://upload.wikimedia.org/wikipedia/commons/7/74/Triangulum.nebula.full.jpg Gas and other particles is space cluster together they form a mass that is called a Interstellar Gas Cloud or Nebula. As more gas and particulate cluster the gravitational pull of the Nebula strengthens and pulls more particles to gain more mass, thus strengthening it’s gravitational pull further

4. Low Mass Star, Stage 2:ProtoStar Info: Notes Picture: http://www.msnbc.msn.com/id/25959575/displaymode/1168/rstry/25959579/rpage/1/ Once the Nebula gathers enough mass the gravity starts to try and pull it together while the atoms themselves try to push apart. The actions of the atoms trying to push apart and the gravity trying to push in creates heat and pressure. At that point one of two things happen

5. Low Mass Star, Stage 3Brown Dwarf Info: Notes Picture: http://www.sciencedaily.com/releases/2008/04/080410101146.htm After a ProtoStar one of two things can happen, either it turns into a main sequence star or a Brown Dwarf. A brown Dwarf is a Protostar that didn’t gather enough mass to make enough heat to start fusion, so in the end it just shines dimly, never truly becoming a star.

6. Low Mass Star, Stage 3Main Sequence Star Info: Notes Picture: http://upload.wikimedia.org/wikipedia/commons/7/72/Pleiades_Spitzer_big.jpg If the ProtoStar gathers enough mass and heat it starts to fuse Hydrogen into Helium, once it starts fusing the it would be declared a star This type of star would be called a Main Sequence Star Most stars are Main sequence Stars because this is one of the longest parts of the stars life time.

7. Low Mass Star, Stage 4Red Giant When the star starts to run out of Hydrogen it starts to try and burn Helium in a attempt to keep burning and not to collapse upon it’s self. Helium burns a bright red and the star it’s self expands, thus giving it the name ‘Red Giant’

8. Low Mass Star, Stage 5Planetary Nebula Info: http://fusedweb.llnl.gov/CPEP/Chart_Pages/5.Plasmas/Nebula.html When a Red Giant stars to run out of helium it once again try’s to gain heat by radiating it’s outer layers out wards. As the outer layers dissipate away from the core, the core it’s self becomes incredibly hot and dense, trying to sustain it’s self by fusing Helium into carbon and that into heavier elements.

9. Low Mass Star, Stage 6White Dwarf Info: http://imagine.gsfc.nasa.gov/docs/science/know_l2/dwarfs.html http://en.wikipedia.org/wiki/White_dwarf • A White Dwarf happens after a Planetary Nebula, a star uses all of it’s fuel, after which all that is left is the very hot, very dense core of the star. • It cools down over Millions of years, during which all it does is radiate low-energy X-rays into space. • A white dwarf has a low luminosity but have about half the mass of the sun while it is about the size of the earth.

10. Low Mass Star, Stage 7Black Dwarf A black dwarf happens when a white dwarf becomes cool to the point that it no longer emits significant heat or light of any kind. There are no documented sightings of a black dwarf due to they’re low luminosity, or it could be that our universe is simply too young for us to have any black dwarf yet

11. High Mass Stars A Star of Higher Mass

12. High Mass Star, Stage 1 Interstellar Gas Cloud Info: http://library.thinkquest.org/3103/nonshocked/topics/interstellar/interstellar.html Picture: http://upload.wikimedia.org/wikipedia/commons/7/74/Triangulum.nebula.full.jpg • Like the low mass stars, high mass stars Start the same way. • Gas and other particles is space cluster together they form a mass that is called a Interstellar Gas Cloud or Nebula. • As more gas and particulate cluster the gravitational pull of the Nebula strengthens and pulls more particles to gain more mass, thus strengthening it’s gravitational pull further

13. High Mass Star, Stage 2ProtoStar • The only difference between a low mass star and a high mass star at this point is how many atoms and mass they gain • Once the Nebula gathers enough mass the gravity starts to try and pull it together while the atoms themselves try to push apart. • The actions of the atoms trying to push apart and the gravity trying to push in creates heat and pressure.

14. High Mass Star, Stage 3Massive Main Sequence Star • As the Protostar starts to burn hydrogen it would now be called a star, but due to it’s mass it would be declared a Massive Main Sequence Star instead of a star of small or standard size which would be called a Main Sequence Star. • Due to the mass of the star it has the ability to burn hotter then most stars, using it’s fuel faster and thus going into the next stage of events faster.

15. High Mass Star, Stage 4Super Nova • A Super nova is a stellar explosion • They are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading over several weeks or months. • During the time a Super Nova is around, it radiates as much energy as the sun in it’s entire life time. • After a Super Nova one of two things can happen.

16. High Mass Star, Stage 5Neutron Star Info: http://www.universetoday.com/guide-to-space/stars/what-is-a-neutron-star/ After a super nova, the remains of the star could become a Neutron Star To get a Neutron Star you need to have star that's larger than about 1.5 solar masses and less than 5 times the mass of the sun. If you have some where around that mass then after the super nova the protons and electrons of atoms are forced together into neutrons. When neutron stars form, they maintain the momentum of the entire star, but now they're just a few kilometers across. This causes them to spin at tremendous rates, sometimes as fast as hundreds of times a second. Just one teaspoon of a neutron star would have the mass of over 5 x 1012 kilograms.

17. High Mass Star, Stage 5Black Hole Info: http://www.windows.ucar.edu/tour/link=/the_universe/BH.html • A black hole is an object which has such high gravitational pull that not even light can escape. Hence it is black. • But in the black hole case the initial star was so massive that nothing could stop its gravitational collapse. All the matter of the star's core is crushed to an infinitely small point, a singularity. • What would it be like to enter a black hole? Not pleasant. First, as you approach the black hole the difference in the gravitational pull on your head compared to your feet (known as tidal forces) would rip you apart. But suppose you survived that. Once you cross the event horizon there is no turning back. Then the only thing to do is avoid the black hole itself at all costs. If you run into that singularity it will crush your body right out of existence.