Precise Ages of Field Stars From White Dwarf Companions in Gaia DR2

Understand

We analyze 4\,050 wide binary star systems involving a white dwarf (WD) and usually a main sequence (MS) star, drawn from the large sample assembled by \citet[][hereafter, T20]{Tian_2020}.

• Using the modeling code BASE-9, we determine the system's ages, the WD progenitors' ZAMS masses, the extinction values ($A_V$), and the distance moduli.
• Discarding the cases with poor age convergences, we obtain ages for 3\,551 WDs, with a median age precision of $\sigma_{\tau}/\tau = 20$\%, and system ages typically in the range of 1-6 Gyr.
• We validated these ages against the very few known clusters and through cross-validation of 236 WD-WD binaries.