Option D.4 Flashcards
p-p chain
The fusion reactions that occur in the stellar cores of stars in the main sequence, converting four hydrogen nuclei into one helium-4 nucleus
CNO cycle
A second fusion reaction that occurs in stellar cores of stars on the main sequence, converting four hydrogen nuclei into a helium-4 nucleus with the use of carbon, nitrogen and oxygen nuclei as catalysts
When is the CNO cycle more dominant than the p-p chain?
In stars that are 1.5 times greater than the sun’s mass or with extremely high temperatures
Triple-alpha process
A fusion reaction that occurs after a star leaves the main sequence, converting three helium-4 nuclei into a carbon-12 nucleus
How is a type Ia supernova formed?
A white dwarf in a binary star system accretes gas from its companion star which becomes a red giant. The mass reaches the Chandrasekhar limit of 1.4 solar masses and explodes
How are type II supernovae formed?
Stars with 8-40 times the solar mass that collapse when they reach the Chandrasekhar limit, increasing the core temperature so that photons can disintegrate nuclei into protons and neutrons, and electrons are captured by protons to produce neutrons. Core continues collapsing until reaches nuclear density, then core bounce occurs and star explodes outwards
Core bounce
When neutrons become degenerate and the core of a star stiffens and becomes incompressible, reversing collapse
Slow neutron capture
Nucleosynthesis process that occurs in relatively low neutron flux and intermediate temperatures in stars, creating heavier nuclei through β-decay
Rapid neutron capture
Nucleosynthesis process that occurs in the high neutron flux and high temperature conditions of core-collapse supernovae. Neutrons are captured rapidly and form super-neutron-rich isotopes that may undergo β-decay
Differences in hydrogen lines between type Ia and type II supernova
No hydrogen lines are in type Ia while they are present for type II
