Spectroscopic and photometric studies of white dwarfs in the Hyades

TL;DR

This study reviews and assesses the membership of white dwarf candidates in the Hyades cluster using spectroscopic, photometric data, and contamination simulations, highlighting unresolved issues about older white dwarfs in the cluster.

Contribution

The paper critically evaluates new white dwarf candidates in the Hyades cluster, combining observational data and contamination modeling to refine cluster membership.

Findings

Six white dwarfs may be Hyades members.

Three candidates have uncertain membership status.

Field star contamination is significant among candidates.

Abstract

The Hyades cluster is known to harbour ten so-called classical white dwarf members. Numerous studies through the years have predicted that more than twice this amount of degenerate stars should be associated with the cluster. Using the PPMXL catalog of proper motions and positions, a recent study proposed 17 new white dwarf candidates. We review the membership of these candidates by using published spectroscopic and photometric observations, as well as by simulating the contamination from field white dwarfs. In addition to the ten classical Hyades white dwarfs, we find six white dwarfs that may be of Hyades origin and three more objects that have an uncertain membership status due to their unknown or imprecise atmospheric parameters. Among those, two to three are expected as field stars contamination. Accurate radial velocity measurements will confirm or reject the candidates. One consequence is that the longstanding problem that no white dwarf older than ~340 Myr appears to be associated with the cluster remains unsolved.