The Solar Neighborhood. XXI. Parallax Results from the CTIOPI 0.9m Program: 20 New Members of the 25 Parsec White Dwarf Sample

TL;DR

This paper reports 20 new precise parallax measurements for white dwarfs within 25 parsecs, increasing the known nearby white dwarf sample by 20%, and provides detailed atmospheric modeling and new pulsation data.

Contribution

It presents the discovery of 20 new white dwarf members within 25 pc, updates parallaxes for known nearby white dwarfs, and includes atmospheric analysis and pulsation observations.

Findings

20 new white dwarfs within 25 pc identified

Updated parallaxes for 7 white dwarfs within 10 pc

Discovered a new ZZ Ceti pulsating white dwarf

Abstract

We present accurate trigonometric parallaxes for 20 new members of the 25 pc white dwarf sample as part of the DENSE project (Discovery and Evalution of Nearby Stellar Embers, http://www.DenseProject.com). Previously, there were a total of 112 white dwarf systems with trigonometric parallaxes placing them within 25 pc and of these, 99 have trigonometric parallaxes known to better than 10%. Thus, the 20 new members presented in this work represent a 20% increase in the number of white dwarfs accurately known to be within 25 pc. In addition, we present updated parallaxes for seven known white dwarfs within 10 pc that have been observed as part of the ASPENS initiative (Astrometric Search for Planets Encircling Nearby Stars) to monitor nearby southern red and white dwarfs for astrometric perturbations from unseen companions. Including a few white dwarf companions and white dwarfs beyond 25 pc, we present a total of 33 trigonometric parallaxes. We perform atmospheric modeling for white dwarfs to determine physical parameters (i.e., effective temperature, log g, mass, and white dwarf age). Finally, a new ZZ Ceti pulsating white dwarf was identified and revised constraints are placed on two mixed H/He atmosphere cool white dwarfs that display continuum absorption in the near-infrared.