vice.primordial

The VICE dataframe: primordial abundances

Stores the abundance by mass of each element following big bang nucleosynthesis. Stored values are of type float, and are zero for all elements with the exception of helium, which is assigned a value of \(Y_\text{p} = 0.24721 \pm 0.00014\) (Pitrou et al. 2021 [1]).

New in version 1.1.0: Previous versions of VICE did not implement helium, and therefore did not require any information on primordial abundances.

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

Notes

In versions >= 1.3.0, the primordial abundance of helium is taken to be \(Y_\text{p} = 0.24721 \pm 0.00014\) (Pitrou et al. 2021), which updates the value of \(Y_\text{p} = 0.24672 \pm 0.00017\) (Planck Collaboration et al. 2016 [2]; Pitrou et al. 2018 [3]; Pattie et al. 2018 [4]) from previous versions of VICE based on updates to the neutron lifetime and the \(\text{D}(p, \gamma)^3\text{He}\) reaction.

Example Code

>>> import vice
>>> vice.primordial['o']
0.0
>>> vice.primordial['he']
0.24721
>>> vice.primordial['c']
0.0