E5+STELLAR+PROCESSES+AND+STELLAR+EVOLUTION

Back to IB PHYSICS > IB ASTROPHYSICS OPTION [|ESA NOTES ON STELLAR PROCESSES AND EVOLUTION] =STELLAR PROCESSES AND STELLAR EVOLUTION= [|FAMOUS STARS PODCAST] with extensive shownotes STELLAR EVOLUTION GALLERY - I have chosen some good images which explain the processes in different ways. Look at each of them and decide which helps you best to understand stellar evolution. You can also add your own images if you are a member of the wiki.
 * E1 INTRODUCTION TO THE UNIVERSE || E2 STELLAR RADIATION AND STELLAR TYPES || E3 STELLAR DISTANCES || E4 COSMOLOGY || E5 STELLAR PROCESSES AND STELLAR EVOLUTION || E6 GALAXIES AND THE EXPANDING UNIVERSE ||

Describe the conditions that initiate fusion in a star. Particles are close enough for gravitation to collapse gas cloud. PE converts to KE. M ** ain sequence star: **Hydrogen to helium fusion starts. Stops contracting.
 * Nucleosynthesis **
 * Protostar:** very hot, surrounded by dust.
 * Pre-main sequence star:** after 100 000 years, dust cloud blown off. Still contracting

State the effect of a star’s mass on the end product of nuclear fusion. __ Small mass (below 4 solar mass) __ : when all H fused to He, no more fusion.

__Large mass (above 4 solar mass)__: carbon, heavier elements created by fusion in layers within the star up to iron.

Outline the changes that take place in nucleosynthesis when a star leaves the main sequence and becomes a red giant. Students need to know an outline only of the processes of helium fusion and silicon fusion to form iron.

**Giant star**: when hydrogen fusion is over in the core, it collapses and gets hotter causing surrounding hydrogen to start to fuse. It expands to a giant.


 * Evolutionary paths of stars and stellar processes **

Apply the mass–luminosity relation.

Explain how the Chandrasekhar and Oppenheimer–Volkoff limits are used to predict the fate of stars of different masses. Max mass of white dwarf is **Chandrasekhar limit = 1.4 solar mass.**
 * Small star: (**below 4 solar masses) no fusion beyond helium. Contracts until electron degeneracy pressure stops it. White dwarf.

Above Chandrasekhar limit, continues to contract, overcome electron degeneracy pressure, neutrons form from protons and electrons. **Neutron star.**

Neutron star (mass below 3 solar masses = **Oppenheimer-Volkoff** limit) will not collapse further due to neutron degeneracy.

Neutron star (above 3 solar masses) will overcome neutron degeneracy and collapse to a black hole.

Compare the fate of a red giant and a red supergiant.

students should know that: • a red giant forms a planetary nebula and then becomes a white dwarf • a white dwarf is stable due to electron degeneracy pressure • a red supergiant experiences a supernova and becomes a neutron star or collapses to a black hole • a neutron star is stable due to neutron degeneracy pressure.

[|ANATOMY OF A BLACK HOLE] - animation

Draw evolutionary paths of stars on an HR diagram.



Outline the characteristics of pulsars.