We have exploited the very precise parallaxes , proper motions and photometry of Gaia Data Release 2 to study white dwarf members of the Hyades star cluster . Gaia photometry and parallaxes for the eight DA white dwarfs confirmed members have been then used to compute absolute magnitudes and colours .
These were compared to three independent sets of white dwarf evolutionary tracks , to derive cooling times and white dwarf ( final ) masses .
All sets of models provide the same mass values , with only small differences in the cooling ages .
The precision in the derived masses and cooling ages is typically 1-3 % .
Our derived masses are generally consistent with spectroscopic estimates from the literature , whilst cooling ages are generally larger .
The recent estimate of the cluster age from the Gaia Data Release 2 main sequence turn off colour-magnitude-diagram ( 790 Myr ) has been employed to derive progenitor ( initial ) masses .
We find a slope of the initial-final mass relation for the Hyades white dwarfs ( masses between \sim 0.67 and \sim 0.84 M _ { \odot } ) steeper than that derived for the same mass range from global estimates –averaged over the whole spectrum of white dwarf masses– irrespectively of the cooling models adopted .
However , when considering the error in this age estimate ( ^ { +160 } _ { -100 } Myr ) , a definitive conclusion on this issue can not be reached yet .
The lower limit of 690 Myr ( closer to the classical Hyades age of 600-650 Myr ) would provide a slope of the initial-final mass relation closer to the global determinations .
We also find hints of an intrinsic spread of the cluster initial-final mass relation for the cluster .