Related papers: White Dwarf based evaluation of the GALEX absolute…
We present metallicity and photometric parallax calibrations for the F and G type dwarfs with photometric, astrometric and spectroscopic data. The sample consists of 168 dwarf stars covering the colour, iron abundance and absolute magnitude…
White dwarfs with infrared excess emission provide a window into the late stages of stellar evolution and the dynamics of circumstellar environments. Using data from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), we…
We present an update of our low-resolution spectroscopic follow-up and model atmosphere analysis of hot subdwarf stars from the Galaxy Evolution Explorer (GALEX) survey. Targets were selected on the basis of colour indices calculated from…
We use galaxies detected in a deep ultraviolet XMM-Newton Optical Monitor image and a model that predicts UV galaxy counts based on local counts and evolution parameters to constrain galaxy evolution to Z=1.2. The 17' square 2000 angstrom…
We present a comparative study of effective temperatures determined from the hydrogen Balmer lines and from the UV energy distribution for 140 DA white dwarfs drawn from the IUE archive. Our results indicate that the optical and UV…
We present results from a GALEX ultraviolet (UV) survey of a complete sample of 390 galaxies within ~11 Mpc of the Milky Way. The UV data are a key component of the composite Local Volume Legacy (LVL), an ultraviolet-to-infrared imaging…
We present a catalog of 71,364 point-like UV sources with SDSS photometry and GALEX FUV-NUV less or equal 0.1mag. The limit corresponds to stellar Teff greater than 15,000 to 20,000K, slightly depending on gravity but nearly…
We present a detailed spectroscopic and photometric analysis of DA and DB white dwarfs drawn from the Sloan Digital Sky Survey with trigonometric parallax measurements available from the Gaia mission. The temperature and mass scales…
The luminosity function of white dwarfs is a powerful tool for studies of the evolution and formation of the Milky Way. The (theoretical) white dwarf cooling sequence provides a useful indicator of the evolutionary time scales involved in…
We used the updated [Fe/H] abundances of 168 F-G type dwarfs and calibrated them to a third order polynomial in terms of reduced ultraviolet excess, $\delta_{0.41}$ defined with $ugr$ data in the SDSS. We estimated the $M_g$ absolute…
We present a new photometric calibration of the WFC3-UVIS and WFC3-IR detectors based on observations collected from 2009 to 2020 for four white dwarfs, namely GRW+70~5824, GD~153, GD~71, G191B2B, and a G-type star, P330E. These…
The space density of white dwarfs is highly uncertain even nearby. This results from the fact that the known sample of white dwarfs is largely incomplete in part because most white dwarfs have been discovered as by-products in non-dedicated…
Near-infrared photometry and spectroscopy is obtained for a heterogeneous sample of nearby white dwarfs with possible excess flux as identified primarily in the Two Micron All Sky Survey. Among the sample of 43 stars are a number of white…
Spectrophotometric observations at high signal-to-noise ratio were obtained of a complete sample of 347 DA white dwarfs from the Palomar Green (PG) Survey. Fits of observed Balmer lines to synthetic spectra calculated from pure-hydrogen…
White dwarf cooling sequences provides a useful indicator of the evolutionary time scales involved in the chronometry and star formation history of the galactic disk and, for this reason, the luminosity function of white dwarfs has become a…
We present a new procedure for photometric parallax estimation. The data for 1236 stars provide calibrations between the absolute magnitude offset from the Hyades main-sequence and the UV-excess for different (B-V)o colour-index intervals,…
This paper presents new trigonometric parallaxes and proper motions for 214 stars. The measurements were made at the US Naval Observatory Flagstaff Station (NOFS) between 1989 and 2017, and the average uncertainty in the parallax values is…
We rederive the luminosity function for the sample of DA white dwarfs from the Kiso Schmidt ultraviolet excess survey (KUV stars) using the spectroscopic method where the atmospheric parameters (Teff and log g) and absolute visual…
We collected F606W- and F814W-band time-series data of the Sagittarius low-reddening window in the Galactic bulge with the Advanced Camera far Surveys mounted on the Hubble Space Telescope. We sampled the region approximately every two…
We present the calibration of the [$\alpha/$Fe] element in terms of ultra-violet excess for 465 dwarf stars with spectral type F0-K2. We used a single calibration, fitted to a third degree polynomial with a square of the correlation…