Hydrogen & Helium Burning in Stars
Hydrogen Burning: 4He,
14N
Michael Wiescher
Joint Institute for Nuclear Astrophysics
Helium Burning: 12C, 16O,
22Ne, n, s-nuclei
What are the critical reactions
that determine the early phase
of stellar evolution and provide
critical neutrino and luminosity
signatures about the burning
mechanism and information
about the seed for subsequent
burning processes.
10
Si-ignition
O-ignition
Ne-ignition
9
log (Tc)
C-ignition
He-ignition
8
H-ignition
7
0
2
4
log (c)
6
8
10
Reaction sequences:
pp-chains, CNO cycles
triple alpha process
2 1H
and its neutrino signatures
2 1H
2H
2H
16O
pp-I
3He
3He
4He
18%
4He
1H
e
-
7Be
pp-III
pp-II
8B
7Li
1H
e
-
8Be
4He
4He
4He
4He
The two most critical Rates
3He(,)7Be
14N(p,)15O
Energy Sources in Helium Burning
Oxygen-16
New low energy data are
needed to improve reliability
of cross section extrapolation
Neutron Sources for s-Process
Generated by α capture on CNO seed material
in AGB stars, He/H zone
13C(α,n)
22Ne(α,n)25Mg
in AGB star He-flash, RGB stars He-core
in RGB stars C-shell
17O(α,n)20Ne
22Ne(α,n)25Mg
New Methods and Techniques
Experimental techniques:
Theoretical Techniques:
Inverse kinematics with
intense heavy ion beams
with recoil separators
Multi-channel R-matrix
theory for improved
extrapolation of cross
section data (AZURE)
Underground experiments
with intense light ion
beams in background free
environments with high
efficiency detector array
Indirect techniques (ANC,
THM) to probe low energy
reaction components
Improved reaction theory
methods for low energy
cross section calculation
(TORUS)
Combination of ANC/THM
data with improved Rmatrix or reaction theory