Related papers: Spectroscopic Analysis of the White Dwarf KUV 0219…

Half of the energy emitted by late-T- and Y-type brown dwarfs emerges at 3.5 < lambda um < 5.5. We present new L' (3.43 < lambda um < 4.11) photometry obtained at the Gemini North telescope for nine late-T and Y dwarfs, and synthesize L'…

We report the discovery of a new eclipsing system less than one arcminute south of the pulsating DB white dwarf KUV 05134+2605. The object could be identified with the point source 2MASSJ0516288+260738 published by the Two Micron All Sky…

We present a detailed analysis of all the known Hot DQ white dwarfs in the Fourth Data Release of the Sloan Digital Sky Survey (SDSS) recently found to have carbon dominated atmospheres. Our spectroscopic and photometric analysis reveals…

LS V +4621 is the DAO-type central star of the planetary nebula Sh 2-216. We perform a comprehensive spectral analysis of high-resolution, high-S/N ultraviolet observations obtained with FUSE and STIS aboard the HST as well as the optical…

We report the discovery of two new hot, hydrogen-rich subdwarfs (sdB) in close binary systems. The hot subdwarfs, GALEX J0321+4727 and GALEX J2349+3844, were selected from a joint optical-ultraviolet catalogue of hot sub-luminous stars…

We present a spectro-photometric analysis of 2880 cool white dwarfs within 100 pc of the Sun and cooler than Teff = 10,000 K, with grizy Pan-STARRS photometry and Gaia trigonometric parallaxes available. We also supplement our data sets…

We present ten new ultra-cool dwarfs in seven wide binary systems discovered using $\textit{Gaia}$ DR2 data, identified as part of our $\textit{Gaia}$ Ultra-Cool Dwarf Sample project. The seven systems presented here include an L1 companion…

In the framework of our extensive modeling study of the spectral evolution of white dwarfs, we present here a new set of detailed calculations of the transport of residual hydrogen in helium-rich white dwarfs. First, we investigate the…

We report the discovery of spectroscopic variations in the magnetic DBA white dwarf SDSS J091016.43+210554.2. Follow-up time-resolved spectroscopy at the Apache Point Observatory (APO) and the MMT show significant variations in the H…

We report the first $BV$ light curves and high-resolution spectra of the post-mass transfer binary star WASP 0131+28 to study the absolute properties of extremely low-mass white dwarfs. From the observed spectra, the double-lined radial…

We present a detailed model atmosphere analysis of hot white dwarfs in the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. Our sample includes 19,321 unique targets with $G_{\rm BP}-G_{\rm RP}\leq0$. We use the DESI spectra…

We present spectra for 33 previously unclassified white dwarf systems brighter than V = 17 primarily in the southern hemisphere. Of these new systems, 26 are DA, 4 are DC, 2 are DZ, and 1 is DQ. We suspect three of these systems are…

Hydrogen-rich white dwarfs (WDs) comprise the majority of the WD population, but are only rarely found at the very hot end of the WD cooling sequence. A small subgroup that exhibits both hydrogen and helium lines in their spectra, the…

White dwarfs with helium-dominated atmospheres comprise approximately 20% of all white dwarfs. Among the open questions are the total masses and the origin of the hydrogen traces observed in a large number and the nature of the deficit of…

We present the results of a radial velocity survey designed to measure the fraction of double degenerates among DA white dwarfs. The narrow core of the H-alpha line was observed twice or more for 46 white dwarfs yielding radial velocities…

We present the discovery of an unusual, tidally-distorted extremely low mass white dwarf (WD) with nearly solar metallicity. Radial velocity measurements confirm that this is a compact binary with an orbital period of 2.6975 hrs and a…

The characterization of white dwarf atmospheres is crucial for accurately deriving stellar parameters such as effective temperature, mass, and age. We aim to classify the population of white dwarfs up to 500 pc into hydrogen-rich or…

We use hierarchical Bayesian modelling to calibrate a network of 32 all-sky faint DA white dwarf (DA WD) spectrophotometric standards ($16.5 < V < 19.5$) alongside three CALSPEC standards, from 912 \r{A} to 32 $\mu$m. The framework is the…

We have acquired new time series photometry of the two pulsating DB white dwarf stars KUV 05134+2605 and PG 1654+160 with the Whole Earth Telescope. Additional single-site photometry is also presented. We use all these data plus all…

We present an overview of the sample of northern hemisphere white dwarfs within 40 pc of the Sun detected from $Gaia$ Data Release 2 (DR2). We find that 521 sources are spectroscopically confirmed degenerate stars, 111 of which were first…