Probing The Lower Mass Limit for Supernova Progenitors and the High-Mass End of the Initial-Final Mass Relation from White Dwarfs in the Open Cluster M35 (NGC 2168)

TL;DR

This study of white dwarfs in the open cluster M35 refines the initial-final mass relation, estimates the lower mass limit for supernova progenitors, and confirms the cluster's distance and extinction parameters.

Contribution

It provides new empirical data on the high-mass end of the initial-final mass relation and estimates the maximum progenitor mass for white dwarfs in M35.

Findings

White dwarf masses and progenitor masses are consistent with previous linear IFMR models.

The lower mass limit for supernova progenitors is estimated at ~5.1-5.2 solar masses from M35 data.

Including other clusters raises the maximum progenitor mass estimate to about 7.1 solar masses.

Abstract

We present a photometric and spectroscopic study of the white dwarf population of the populous, intermediate-age open cluster M35 (NGC 2168); this study expands upon our previous study of the white dwarfs in this cluster. We spectroscopically confirm 14 white dwarfs in the field of the cluster: 12 DAs, 1 hot DQ, and 1 DB star. For each DA, we determine the white dwarf mass and cooling age, from which we derive the each star's progenitor mass. These data are then added to the empirical initial-final mass relation (IFMR), where the M35 WDs contribute significantly to the high-mass end of the relation. The resulting points are consistent with previously-published linear fits to the IFMR, modulo moderate systematics introduced by the uncertainty in the star cluster age. Based on this cluster alone, the observational lower limit on the maximum mass of white dwarf progenitors is found to be ~5.1-5.2 solar masses at the 95% confidence level; including data from other young open clusters raises this limit as high as 7.1 solar masses, depending on the cluster membership of three massive WDs and the core-composition of the most massive WDs. We find that the apparent distance modulus and extinction derived solely from the cluster white dwarfs [(m-M)v=10.45 +/- 0.08 and E(B-V)=0.185 +/- 0.010, respectively] is fully consistent with that derived from main-sequence fitting techniques. Four M35 WDs may be massive enough to have oxygen-neon cores; the assumed core composition does not significantly affect the empirical IFMR. Finally, the two non-DA WDs in M35 are photometrically consistent with cluster membership; further analysis is required to determine their memberships.