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Home , CNO cycle

Supernovae &

1.What are supernovae? What the different kinds of supernovae?

2.What is nucleosynthesis? What does it happen? Supernovae: two main types

Type II – massive

Type Ia – explosion of in binary systems)

Also, Type Ib – massive stars but no H envelope

Type Ic – massive stars but no H/He envelope Type II SN: core collapses into a neutron , blows off envelope

8–25 Msun: NS 25–100 Msun: BH Type Ia occurs in binaries when companion transfers mass to WD Type Ibc: happens in massive stars sans H/He envelope Light curves of SN: Ia vs. II When does nucleosynthesis happen?

Stellar nucleosynthesis 2. Main Seq. 3.

low mass high mass star (< 5 M ) 1 & 5. star (>5 M ) molecular sun high mass cloud star (>5 M ) 4. sun

5. 4. 4. White dwarf

Nucleosynthesis possible 5. Black hole if white dwarf in binary system (during or supernova) The -proton chain is the staple of main-sequence dwarfs

Hydrogen Deuterium

Helium

Occurs in stars > 0.08 Msun Higher-mass stars fuse H via the CNO cycle

Occurs in stars > 1.1 Msun fuses mainly via the triple-

Occurs in stars > 0.5 Msun Elements heavier than form via He-capture

Occurs in stars > 5 Msun Other fusion reactions can occur as well Where are different elements produced?

Q: How do we know is happening in stars? Review: Supernovae & Nucleosynthesis When does nucleosynthesis happen?

Stellar nucleosynthesis 2. Main Seq. 3. Red Giant

low mass high mass star (< 5 M ) 1 & 5. star (>5 M ) sun molecular sun high mass cloud star (>5 M ) 4. Planetary nebula sun

5. Neutron star 4. Supernova 4. White dwarf

Nucleosynthesis possible 5. Black hole if white dwarf in binary system (during nova or supernova) Nucleosynthesis

Nucleosynthesis happens when nucleons combine to produce energy

4 H —> He (p-p chain) is the staple of solar-type stars

Heavier stars burn with the CNO cycle

He fuses to C

Heavier elements are produced by capturing He

Iron is the heaviest element produced by fusion

Heavier elements are produced by or decay