Related papers: The Torino Observatory Parallax Program: White Dwa…
We present the first detailed photometric and spectroscopic study of the white dwarfs (WDs) in the field of the ~225 Myr old (log tau_cl = 8.35) open cluster NGC 1039 (M34) as part of the ongoing Lick-Arizona White Dwarf Survey. Using…
We present a new determination of the distance (and age) of the Galactic globular cluster 47 Tucanae (NGC 104) based on the fit of its white dwarf (WD) cooling sequence with the empirical fiducial sequence of local WD with known…
For a decade there has been a factor of 2.5 gap in luminosity between the 275K WISE J085510.83-071442.5 (Luhman 2014) and all other Y dwarfs, with Teff >= 350K. Recently three objects were found which may fall in this gap. Two are…
We present deep VI photometry of stars in the globular cluster M5 (NGC 5904) based on images taken with the Hubble Space Telescope. The resulting color-magnitude diagram reaches below V ~ 27 mag, revealing the upper 2-3 magnitudes of the…
Using the Hubble space Telescope Fine Guidance Sensor, we have measured the trigonometric parallax of the bright cataclysmic variable 1223 Sgr. The absolute parallax is pi(abs)= 1.96+-0.18mas, making V1223 Sgr the most distant CV with a…
We report the discovery of a nearby M5.0V dwarf at 24.6 pc, SCR 1848-6855, that is orbited by an unusual companion causing an astrometric perturbation of more than 200 milli-arcseconds. This is by far the largest perturbation found to date…
We begin the search for extremely-low mass ($M\leq0.3M_{\odot}$, ELM) white dwarfs (WDs) in the southern sky based on photometry from the VST ATLAS and SkyMapper surveys. We use a similar color-selection method as the Hypervelocity star…
In this paper we present our project that aims at determining accurate distances and proper motions for the Y brown dwarf population using the Hubble Space Telescope. We validate the program with our first results, using a single new epoch…
Pulsars with compact companions in close eccentric orbits are unique laboratories for testing general relativity and alternative theories of gravity. Moreover, they are excellent targets for future gravitational wave experiments like LISA…
An unresolved, likely L dwarf companion to the DA white dwarf GD1400 is reported. This would be only the second such system known, discovered 17 years after the prototype L dwarf, GD165B, was determined to be a companion to a white dwarf.…
We have discovered a detached pair of white dwarfs (WDs) with a 12.75 min orbital period and a 1,315 km/s radial velocity amplitude. We measure the full orbital parameters of the system using its light curve, which shows ellipsoidal…
We investigate the membership in double, triple or higher-order-multiplicity systems of 54 pairs with at least one bright M dwarf in the solar neighbourhood. These M dwarfs are potential targets of radial-velocity surveys for exoplanets. We…
We present the first trigonometric parallax and distance for a young planetary mass object. A likely TW Hya cluster member, 2MASSW J1207334-393254Ab (hereafter 2M1207Ab) is an M8 brown dwarf with a mid to late L type planetary mass…
We search for photometric variability in more than 23,000 known and candidate white dwarfs, the largest ultraviolet survey compiled for a single study of white dwarfs. We use gPhoton, a publicly available calibration/reduction pipeline, to…
We present 916 trigonometric parallaxes and proper motions of newly discovered nearby stars from the United States Naval Observatory (USNO) Robotic Astrometric Telescope (URAT). Observations were taken at the Cerro Tololo Interamerican…
This paper presents a sensitive and comprehensive IRAC 3-8 $\mu$m photometric survey of white dwarfs for companions in the planetary mass regime with temperatures cooler than the known T dwarfs. The search focuses on descendents of…
We report on photometric and spectroscopic observations of white dwarf companions to four binary radio millisecond pulsars, leading to the discovery of companions to PSRs J0614-3329, J1231-1411 and J2017+0603. We place limits on the…
The TW Hya Association (TWA) is a nearby stellar association with an age of $\sim$ 5-10 Myr. This is an important age for studying the late stages of star and planet formation. We measure the parallaxes of 14 candidate members of TWA. That…
Deep Hubble Space Telescope (HST) observations with WFPC2 of the nearby globular cluster NGC 6752 have allowed us to obtain accurate photometry for the cluster white dwarfs (WD). A sample of local WDs of known trigonometric parallax and…
I used the 2.4 m Hiltner telescope at MDM Observatory in an attempt to measure trigonometric parallaxes for 14 cataclysmic variable stars. Techniques are described in detail. In the best cases the parallax uncertainties are below 1 mas, and…