wdwarfdate: A Python Package to Derive Bayesian Ages of White Dwarfs
Abstract
White dwarfs have been successfully used as cosmochronometers in the literature; however, their reach has been limited in comparison to their potential. We present wdwarfdate, a publicly available Python package to derive the Bayesian age of a white dwarf, based on its effective temperature (T _{eff}) and surface gravity (log g). We make this software easy to use with the goal of transforming the usage of white dwarfs as cosmochronometers into an accessible tool. The code estimates the mass and cooling age of the white dwarf, as well as the mass and mainsequence age of the progenitor star, allowing for a determination of the total age of the object. We test the reliability of the method by estimating the parameters of white dwarfs from previous studies and find agreement with the literature within measurement errors. In addition, we use wdwarfdate to infer the total age of 18 white dwarfs that are in possible wide binaries with M dwarfs; this leads to an additional set of agecalibrated lowmass stars. By analyzing the limitation of the code we find a typical uncertainty of 10% on the total age when both input parameters have uncertainties of 1%, and an uncertainty of 25% on the total age when T _{eff} has an uncertainty of 10% and log g of 1%. Furthermore, wdwarfdate assumes singlestar evolution and can be applied to calculate the total age of a white dwarf with parameters in the range 1500 ≲ T _{eff} ≲ 90,000 K and 7.9 ≲ log g ≲ 9.3. Finally, the code assumes a uniform mixture of C/O in the core and singlestar evolution, which is reliable in the range of white dwarf masses 0.451.1 M _{⊙}(7.73 ≲ log g ≲ 8.8).
 Publication:

The Astronomical Journal
 Pub Date:
 August 2022
 DOI:
 10.3847/15383881/ac7788
 arXiv:
 arXiv:2206.05388
 Bibcode:
 2022AJ....164...62K
 Keywords:

 White dwarf stars;
 Fundamental parameters of stars;
 Stellar ages;
 Bayesian statistics;
 Open source software;
 1799;
 555;
 1581;
 1900;
 1866;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 19 pages, 12 figures, 2 tables, Accepted for publication in AJ