vice.sources
============

The VICE dataframe: nucleosynthetic sources

Stores the dominant astrophysical enrichment channels of each element.
These values are adopted from Johnson (2019) [1]_. Stored values are of
type ``list``, elements of which are of type ``str``.

	- "BBN": Big Bang Nucleosynthesis
		A statistically significant portion of this element's present-day
		abundances was present prior to the onset of star formation in the
		universe.
	- "CCSNE": Core Collapse Supernovae
		A statistically significant portion of this element's present-day
		abundances is due to massive star explosions.
	- "SNEIA": Type Ia Supernovae
		A statistically significant portion of this element's present-day
		abundances is due to white dwarf explosions.
	- "AGB": Asymptotic Giant Branch Stars
		A statistically significant portion of this element's present-day
		abundances is due to synthesis in AGB stars.
	- "NSNS": Neutron Star Mergers, R-process Nucleosynthesis
		A statistically significant portion of this element's present-day
		abundances is due to neutron star mergers, or other astrophysical
		sites of r-process nucleosynthesis.

Indexing
--------
- ``str`` [case-insensitive]
	The symbol of a chemical element as it appears on the periodic table.

Item Assignment
---------------
This instance of the VICE dataframe does not support item assignment.

Functions
---------
- keys
- todict

Example Code
------------
>>> import vice
>>> vice.sources['o']
["CCSNE"]
>>> vice.sources['he']
["BBN", "CCSNE", "AGB"]
>>> vice.sources['fe']
["CCSNE", "SNEIA"]

.. [1] Johnson (2019), Science, 363, 474