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