An Extremely Massive White Dwarf Escaped From the Hyades Star Cluster

TL;DR

This paper reports the discovery of a highly massive white dwarf likely originating from the Hyades cluster, potentially the most massive single-evolution white dwarf identified, using Gaia data and follow-up spectroscopy.

Contribution

It presents the identification and confirmation of a new extremely massive white dwarf as an escapee from the Hyades, highlighting its significance in stellar evolution studies.

Findings

Discovery of a 1.317 solar mass white dwarf linked to Hyades

Spectroscopic analysis confirms a non-magnetized hydrogen atmosphere

Estimated 97.8% probability of being a true cluster escapee

Abstract

We searched the Gaia DR3 database for ultramassive white dwarfs with kinematics consistent with having escaped the nearby Hyades open cluster, identifying three such candidates. Two of these candidates have masses estimated from Gaia photometry of approximately 1.1 solar masses; their status as products of single stellar evolution that have escaped the cluster was deemed too questionable for immediate follow-up analysis. The remaining candidate has an expected mass >1.3 solar masses, significantly reducing the probability of it being an interloper. Analysis of follow-up Gemini GMOS spectroscopy for this source reveals a non-magnetized hydrogen atmosphere white dwarf with a mass and age consistent with having formed from a single star. Assuming a single-stellar evolution formation channel, we estimate a 97.8% chance that the candidate is a true escapee from the Hyades. With a determined mass of 1.317 solar masses, this is potentially the most massive known single-evolution white dwarf and is by far the most massive with a strong association with an open cluster.