Stellar nucleosynthesis is the process of using nuclear reactions within a stellar core to create/synthesize new atomic nuclei (chemical elements) from pre-existing nuclei or nucleons (i.e. protons & neutrons).
> [!key-idea] Methods of Stellar Nucleosynthesis
>
>![[nucelosynthesis.png|align:center|400]]
>
> - Hydrogen fusion:
> - [[Deuteron Fusion]]
> - [[Proton-Proton Chain]] (PP Chain)
> - [[Carbon-Nitrogen-Oxygen Cycle]] (CNO Cycle)
> - Helium fusion:
> - [[Triple-Alpha Process]] (Triple-$\alpha$ Process)
> - [[Alpha Process]]
> - Fusion of heavier elements:
> - [[Lithium Burning]]
> - [[Carbon Burning]]
> - [[Neon Burning]]
> - [[Oxygen Burning]]
> - [[Silicon Burning]]
> - Production of elements heavier than iron:
> - [[Neutron Capture]]:
> - [[Neutron Capture#s-process|s-process]]
> - [[Neutron Capture#r-process|r-process]]
> - [[Proton Capture]]:
> - [[Proton Capture|p-process]]
> - [[Proton Capture#rp-process|rp-process]]
> - [[Photodisintegration]]
^methods-of-fusion
![[Nuclear Energy Generation Rate#^nuclearBurning-comparison]]
## Rules for Nuclear Reactions
![[SMparticles.png|align:center|400]]
When balancing the left- and right-hand sides of a nuclear reaction, you must conserve:
- Energy
- Charge
- Baryon Number *(i.e. number of baryons on each side)*
- Lepton Number *(i.e. number of leptons on each side)*
> [!note] Matter & Antimatter
>
> When accounting for matter and anitmatter particles, remember that antimatter particles have the **opposite charge sign and lepton number**.
>
## Table of Nuclides
![[nuclides_chart_origins.png]]
For an Interactive Version with Nuclide Data: [Interactive Nuclide Chart - IAEA, Nuclear Data Section](https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html)
**Features:**
- Valley of Stability (also called the **belt of stability**, **nuclear valley**, **energy valley**, or **beta stability valley**)
- The shape of the valley refers to the profile of binding energy as a function of the numbers of neutrons and protons, with the lowest part of the valley corresponding to the region of most stable nuclei.
- The line of stable nuclides down the center of the valley of stability is known as the **line of beta stability**.
- The gradient of the sides of the valley correspond to increasing instability to [[Beta Decay]]
- The boundaries of the valley correspond to the **nuclear drip lines**, where nuclides become so unstable they emit single protons ([[Proton Emission]]) or single neutrons ([[Neutron Emission]]).
- High atomic number boundaries also includes the effect of [[Alpha Decay]] or [[Spontaneous Fission]]
## Periodic Table
![[periodic_table.png]]
In astronomy, this table becomes much similar such that we classify the elements into three categories:
1) Hydrogen ($X$)
2) Helium ($Y$)
3) Metals ($Z$)
> [!note]
> When $X$, $Y$, and $Z$ appear in equations, it refers to the **mass fraction** of hydrogen, helium, and metals , respectively. The number density fraction can vary widely from this quantity.
That said, with further studies in nucleosynthesis and astronomical events, astronomers have learned about the origin of the various chemical abundances in our universe.
![[periodic_table_astro.png]]