Related papers: Discovery of two bright DO-type white dwarfs

We report the discovery of a nearby massive white dwarf with He-H atmosphere. The white dwarf is located at a distance of $74.5\pm0.9$ pc. Its radius, mass, effective temperature, H/He ratio and age are $R=2500\pm100$ km, $M=1.33\pm0.01$…

White dwarfs with metal lines in their spectra act as signposts for post-main sequence planetary systems. Searching the Sloan Digital Sky Survey (SDSS) data release 12, we have identified 231 cool (<9000 K) DZ white dwarfs with strong metal…

We report signal-to-noise ratio SNR ~ 100 optical spectra for four DA white dwarf stars acquired with the GMOS spectrograph of the 8m Gemini north telescope. These stars have 18<g<19 and are around Teff ~ 12000 K, were the hydrogen lines…

We present a detailed model atmosphere analysis of high-dispersion and high signal-to-noise ratio spectra of the heavily polluted DAZ white dwarf GALEX J1931+0117. The spectra obtained with the VLT-Kueyen/UV-Visual Echelle Spectrograph show…

We present the results of a search for white light flares on the ~23,000 cool dwarfs in the Kepler Quarter 1 long cadence data. We have identified 373 flaring stars, some of which flare multiple times during the observation period. We…

We present i and z photometry for 25 T dwarfs and one L dwarf. Combined with published photometry, the data show that the i - z, z - Y and z - J colors of T dwarfs are very red, and continue to increase through to the late-type T dwarfs,…

T and Y-dwarfs are among the coolest and least luminous objects detected, and they can help to understand the properties of giant planets. Their multiplicity properties can shed light on the formation process. We observed a sample six T…

We present full evolutionary calculations appropriate for the study of hot hydrogen-deficent DO white dwarfs, PG 1159 stars, and DB white dwarfs. White dwarf sequences are computed for a wide range of stellar masses and helium envelopes on…

The accretion of planetary debris into the atmospheres of white dwarfs leads to the presence of metal lines in their spectra. Cool metal-rich white dwarfs, which left the main-sequence many Gyr ago, allow the study of the remnants of the…

We present the discoveries of WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5, two low-temperature (1200$-$1400 K), high proper motion T-type subdwarfs. Both objects were discovered via their high proper motion ($>$0.5 arcsec…

The Y-dwarf WISE 1828+2650 is one of the coldest known Brown Dwarfs with an effective temperature of $\sim$300 K. Located at a distance of just 10 pc, previous model-based estimates suggest WISE1828+2650 has a mass of $\sim$5-10 Mj, making…

The spectroscopic sky survey carried out by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) provides the largest stellar spectra library in the world until now. A large number of new DA white dwarfs had been…

We present the first mid-infrared spectra of two cool white dwarfs obtained with the Spitzer Space Telescope. We also present 3.5-8 micron photometry for 19 cool white dwarfs with 5000K < Teff < 9000K. We perform a detailed model atmosphere…

2MASS J05513444+4135297 (herafter J0551+4135) is the only pulsating DAQ white dwarf known with a carbon and hydrogen atmosphere. Its unusual atmospheric composition and kinematics indicate a white dwarf merger origin. We present time-series…

With the launch of the Wide-Field Infrared Survey Explorer (WISE), a new era of detecting planetary debris around white dwarfs has begun with the WISE InfraRed Excesses around Degenerates (WIRED) Survey. The WIRED Survey will be sensitive…

We present a new Y dwarf, WISE J030449.03-270508.3, confirmed from a candidate sample designed to pick out low temperature objects from the WISE database. The new object is typed Y0pec following a visual comparison with spectral standards,…

We report the identification of LSR J0745+2627 in the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool white dwarf with kinematics and age compatible with the thick-disk/halo population.…

We report a nearby L7.5 dwarf discovered using the Preliminary Data Release of the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All-Sky Survey (2MASS). WISEP J180026.60+013453.1 has a motion of 0.42 arcsec/yr and an…

We present new spectroscopic data for Gaia DR3 2309499817384726016 (WD0008-350A) and its two wide, co-moving, low-mass companions. We confirm the white dwarf is a hydrogen-rich DA, with T$_{\rm eff}$=6200$\pm$90~K and a mass of…

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…