When Do Stars Go BOOM?

TL;DR

This paper investigates the maximum mass of stars that can produce white dwarfs by searching for massive white dwarf candidates in young star clusters, including the first extragalactic white dwarfs, to better understand stellar evolution limits.

Contribution

It presents the first search for massive white dwarf candidates in extragalactic clusters, expanding the known sample and providing new insights into stellar mass limits for white dwarf formation.

Findings

Identified five potential white dwarf candidates in a Magellanic Cloud cluster.

Discovered the first extragalactic white dwarf candidates.

Highlights the need for spectroscopy to confirm these candidates.

Abstract

The maximum mass of a star that can produce a white dwarf (WD) is an important astrophysical quantity. One of the best approaches to establishing this limit is to search for WDs in young star clusters in which only massive stars have had time to evolve and where the mass of the progenitor can be established from the cooling time of the WD together with the age of the cluster. Searches in young Milky Way clusters have not thus far yielded WD members more massive than about 1.1$~M_{\odot}$, well below the Chandrasekhar mass of $1.38~M_{\odot}$, nor progenitors with masses in excess of about $6~M_{\odot}$. However, the hunt for potentially massive WDs that escaped their cluster environs is yielding interesting candidates. To expand the cluster sample further, we used HST to survey four young and massive star clusters in the Magellanic Clouds for bright WDs that could have evolved from stars as massive as 10$~M_{\odot}$. We located five potential WD candidates in the oldest of the four clusters examined, the first extragalactic single WDs thus far discovered. As these hot WDs are very faint at optical wavelengths, final confirmation will likely have to await spectroscopy with 30-metre class telescopes.