Related papers: A massive white dwarf member of the Coma Berenices…
We report identification of the optical counterpart to the companion of the millisecond pulsar J2317+1439. At the timing position of the pulsar, we find an object with $g=22.96\pm0.05$, $r=22.86\pm0.04$ and $i=22.82\pm0.05$. The magnitudes…
With the Keck I Low-Resolution Imaging Spectrometer we have observed nine white dwarf candidates in the very rich open cluster NGC 2099 (M37). The spectroscopy shows seven to be DA white dwarfs, one to be a DB white dwarf, and one to be a…
The Hubble Space Telescope observation of the double white dwarf (WD) binary SDSS J125733.63$+$542850.5 reveal that the massive WD has a surface gravity log$g_1\sim8.7$ (which implies a mass of $M_1\sim1.06~{\rm M_\odot}$) and an effective…
We report the spectroscopic confirmation of four further white dwarf members of Praesepe. This brings the total number of confirmed white dwarf members to eleven making this the second largest collection of these objects in an open cluster…
We have used multi-epoch images from the Infrared Array Camera on board the Spitzer Space Telescope to search for substellar companions to stars in the solar neighborhood based on common proper motions. Through this work, we have discovered…
We present the initial-final mass relation derived from 10 white dwarfs in wide binaries that consist of a main sequence star and a white dwarf. The temperature and gravity of each white dwarf was measured by fitting theoretical model…
We present the preliminary results of a survey of the open clusters NGC3532 and NGC2287 for new white dwarf members which can help improve understanding of the form of the upper end of the stellar initial mass-final mass relation. We…
We present measurements of the interferometrically-resolved binary star system 12 Com and the single giant star 31 Com in the cluster Coma Berenices. 12 Com is a double-lined spectroscopic binary system consisting of a G7 giant and an A3…
The old, solar metallicity open cluster Messier 67 has long been considered a lynchpin in the study and understanding of the structure and evolution of solar-type stars. The same is arguably true for stellar remnants - the white dwarf…
We present the discovery of a new double detonation progenitor system consisting of a hot subdwarf B (sdB) binary with a white dwarf companion with an P=76.34179(2) min orbital period. Spectroscopic observations are consistent with an sdB…
We report the results of a CCD imaging survey, complimented by astrometric and spectroscopic follow-up studies, that aims to probe the fate of heavy-weight intermediate mass stars by unearthing new, faint, white dwarf members of the rich,…
We report on the identification of 22 new cool DO-type white dwarfs (WD) detected in Data Release 10 (DR10) of the Sloan Digital Sky Survey (SDSS). Among them, we found one more member of the so-called hot-wind DO WDs, which show ultrahigh…
We report the discovery, from our preliminary survey of the Praesepe open cluster, of two new spectroscopically confirmed white dwarf candidate members. We derive the effective temperatures and surface gravities of WD0837+218 and WD0837+185…
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…
We present detailed theoretical mass-radius relations for massive white dwarf stars with oxygen-neon cores. This work is motivated by recent observational evidence about the existence of white dwarf stars with very high surface gravities.…
The bright, nearby DA-type white dwarf (WD) 40 Eridani B is orbited by the M dwarf 40 Eri C, allowing determination of the WD's mass. Until recently, however, the mass depended on orbital elements determined four decades ago, and that mass…
We have identified stellar and substellar members in the nearby star cluster Coma Berenices, using photometry, proper motions, and distances of a combination of 2MASS, UKIDSS, URAT1, and {\it Gaia}/DR2 data. Those with {\it Gaia}/DR2…
A deep imaging survey covering the entire $23\arcmin$ diameter of the old open cluster M67 to $V = 25$ has been carried out using the mosaic imager (UHCam) on the Canada-France-Hawaii Telescope. The cluster color-magnitude diagram (CMD) can…
We re-examine the properties of the high-velocity and extremely low mass white dwarf LP 400-22 and its close companion. Based on an extended observation timeline we determined a binary period of P= 1.01016 d, somewhat longer than the…
We present the results of a photometric and spectroscopic study of the white dwarf candidate members of the intermediate age open clusters NGC3532 and NGC2287. Of the nine objects investigated, it is determined that six are probable members…