.. _yields:

Nucleosynthetic Yields
======================
Due to the associated uncertainties [1]_, VICE takes an agnostic approach to
the user's desired nucleosynthetic yields. Rather than adopting the results of
a nucleosynthesis study, the user declares their yields outright. VICE
includes features which will calculate yields upon request, but requires the
user to explicitly tell it what the yield of each element from each enrichment
channel should be (although there is a set of defaults).

All yields in VICE are defined as *fractional net yields*. This is the
amount of an element that is *produced and ejected* to the interstellar medium
*minus* that which was already present, in units of the star or stellar
population's initial mass. Previously produced nuclei should not be taken into
account, because this is handled via *recycling*. For example, if a stellar
population is born with :math:`1 M_\odot` of oxygen total and ejects
:math:`1 M_\odot` of oxygen back to the interstellar medium, the yield is
zero since there is no net gain.

Yields are also defined for the average star or stellar population.
Stochasticity in yields introduced by, e.g., sampling of the stellar initial
mass function, should not be taken into account in yield calculations
intended for use in VICE.


.. [1] See Andrews, Weinberg, Schoenrich & Johnson (2017), ApJ, 835, 224 and
	the citations therein for a detailed analysis of multiple elements.

.. _yields_ccsne:

.. include:: ccsne.rst

.. _yields_sneia:

.. include:: sneia.rst

.. _yields_agb:

.. include:: agb.rst

.. _fig_yields_agb:

.. include:: agb.fig.rst