Life Cycle of a Star Video (5 min) http://www.youtube.com/watch?v=pm9cqdlqi0a The Life Cycle of Stars Solar Nebula Theory : Is the current theory of how our Solar System formed. This theory states that stars form from the cloud of gas and dust in a. Planets stars then form around from the gas and dust cloud that is left after the formation of the star. hydrogen The main gas in a nebula is. Once a star forms, the hydrogen undergoes a process called nuclear. fusion nebula Eagle Nebula together Nuclear Fusion: A process is which hydrogen atoms fuse to form helium atoms. This process releases a large amount of energy. This is released as in stars heat and light Life of a Star Protostar Equilibrium End of Life 1) Protostar sphere 1. Gravity pulls gas and dust together into a rises 2. As matter builds up the pressure and temperature protostar 3. At 10 000 000 degrees Celsius hydrogen atoms within the begin to collide to form helium (this process is called ) fusion glow 4. This fusion reaction causes the star to "turn on" and begin to
2) Equlibrium Once fusion begins, hydrogen is continually consumed and accumulates in the core of the star. Core temperature and pressure increase and the result is a stable state which we refer to as the. gravity outwards Equilibrium = a balance between the force of pulling inwards and gas pressure pushing. helium equilibrium Diagram http://aspire.cosmicray.org/labs/starlife/starlife_eq uilibrium.html The time a star stays in this state depends on its mass. 3) End of Life Once formed, helium can then itself fuse to form elements. equilibrium heavier Eventually however, can no longer be maintained as the hydrogen begins to run out. The end of a stars life occurs when the force of pressure from fusion no longer the gravitational force. balances
How Size Determines the Life of a Star Low Mass Stars Low mass stars (red dwarfs) consume hydrogen at a very rate (~ 100 billion years). During this time, they lose significant, mass and eventually evaporate. The result is a very faint. white dwarf slow Intermediate Mass Stars faster expand Intermediate mass stars consume hydrogen at a rate (~ 10 billion years). As the core contracts from its own gravity, the outer layers. carbon When the core reaches 100 000 000 o C, the helium fuses into. Because of the expansion, the outer layers are much cooler than when the star was in equilibrium. It therefore appears as a. red giant Our Sun is considered an intermediate mass star and will evolve to this phase in about 5 billion years, its diameter expanding beyond the orbit of. Mars Stellar winds will peel away gases of the red giant and over time, its remnant will cool slowly and lose its brightness. It then becomes a. white dwarf The Sun red giant white dwarf
High Mass Stars (Massive Stars) High mass stars consume hydrogen extremely fast (~ 7 million years). Their core gets so hot the helium fuses into heavier elements. This releases a vast amount of energy which causes the star to swell into a. red supergiant http://www.youtube.com/watch?v=zwpz1giehhy In high mass stars, the extremely high temperature of the core of the star allows fusion to create any of the elements that come before on the periodic table iron collapses When a high mass star enters the end of life phase, its iron core and the outer portion of the star causing a supernova which is very bright. expands rapidly neutron starfollowing supernova. A high mass star will become a black hole If it is a very high mass star, it will become a. Summary Chart Size How long for it's lifetime End of life (last 2 steps) Low Mass Star Intermediate Mass Star Massive Star 1. As the size of a star increases, the length of its lifetime, because 2. What size of star can become a blackhole? 3. What type of star is our Sun? 4. On paper draw a flow chart showing what happens for the 3 types of stars in the chart above. 5. On paper define the following: red dwarf, white dwarf, red giant, neutron star, black hole, nebula
Something like this but include the small mass star as well
neutron star A is a type of stellar remnant that can result from the gravitational collapse of a massive star during a supernova event. Neutron stars are the densest and tiniest stars known to exist in the universe; although having only the diameter of about 10 km (6 mi), they may have a mass of several times that of the Sun. Neutron stars probably appear white to the naked eye.