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We report on spectroscopy of the white-dwarf companion of the millisecond radio pulsar PSR J1012+5307. We find strong Balmer absorption lines, as would be expected for a cool DA white dwarf. The profiles are much narrower than usual,…

Astrophysics · Physics 2009-10-28 M. H. van Kerkwijk , P. Bergeron , S. R. Kulkarni

We present the first phase in our ongoing work to use Sloan Digital Sky Survey (SDSS) data to create separate white dwarf (WD) luminosity functions for two or more different mass ranges. In this paper, we determine the completeness of the…

The ESO Supernova Ia Progenitor Survey (SPY) took high-resolution spectra of more than 1000 white dwarfs and pre-white dwarfs. About two thirds of the stars observed are hydrogen-dominated DA white dwarfs. Here we present a catalog and…

Solar and Stellar Astrophysics · Physics 2015-05-13 D. Koester , B. Voss , R. Napiwotzki , N. Christlieb , D. Homeier , T. Lisker , D. Reimers , U. Heber

We present a catalogue of 73,221 white dwarf candidates extracted from the astrometric and photometric data of the recently published Gaia DR2 catalogue. White dwarfs were selected from the Gaia Hertzsprung-Russell diagram with the aid of…

Solar and Stellar Astrophysics · Physics 2018-08-15 F. M. Jiménez-Esteban , S. Torres , A. Rebassa-Mansergas , G. Skorobogatov , E. Solano , C. Cantero , C. Rodrigo

The accurate flux calibration of observational data is vital for astrophysics and cosmology because absolute flux uncertainties of stellar standards propagate into scientific results. With the ever higher precision achieved by telescopic…

The cool white dwarf SDSS J124231.07+522626.6 exhibits photospheric absorption lines of 8 distinct heavy elements in medium resolution optical spectra, notably including oxygen. The Teff = 13000 K atmosphere is helium-dominated, but the…

Solar and Stellar Astrophysics · Physics 2015-05-20 R. Raddi , B. T. Gaensicke , D. Koester , J. Farihi , J. J. Hermes , S. Scaringi , E. Breedt , J. Girven

We present Hubble Space Telescope UV spectra of the 4.6 h period double white dwarf SDSS J125733.63+542850.5. Combined with Sloan Digital Sky Survey optical data, these reveal that the massive white dwarf (secondary) has an effective…

We investigate the detectability of atmospheric spectral features of Earth-like planets in the habitable zone (HZ) around M dwarfs with the future James Webb Space Telescope (JWST). We use a coupled 1D climate-chemistry-model to simulate…

Earth and Planetary Astrophysics · Physics 2019-05-08 F. Wunderlich , M. Godolt , J. L. Grenfell , S. Städt , A. M. S. Smith , S. Gebauer , F. Schreier , P. Hedelt , H. Rauer

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…

Solar and Stellar Astrophysics · Physics 2015-05-27 S. Vennes , A. Kawka , P. Nemeth

We have observed the short-period dwarf novae BW Scl, BC UMa and SW UMa using the Hubble Space Telescope/Space Telescope Imaging Spectrograph. In all three systems, the white dwarf is the dominant source of far-ultraviolet flux, even though…

Astrophysics · Physics 2009-11-11 B. T. Gaensicke , P. Szkody , S. B. Howell , E. M. Sion

We present an analysis of 40 cool helium-rich white dwarfs found in the Hamburg/ESO survey. They were selected for follow-up spectroscopy because of their U-B colour below -0.18, the absence of strong absorption lines, and a continuum shape…

Astrophysics · Physics 2007-05-23 S. Friedrich , D. Koester , N. Christlieb , D. Reimers , L. Wisotzki

Ultracool dwarfs (UCDs) comprise the lowest mass members of the stellar population and brown dwarfs, from M7 V to cooler objects with L, T, and Y spectral types. Most of them have been discovered using wide-field imaging surveys, for which…

Ultra-cool dwarfs of the L spectral type (Teff=1400-2200K) are known to have dusty atmospheres. Asymmetries of the dwarf surface may arise from rotationally-induced flattening and dust-cloud coverage, and may result in non-zero linear…

Solar and Stellar Astrophysics · Physics 2015-05-13 B. Goldman , J. Pitann , M. R. Zapatero Osorio , C. A. L. Bailer-Jones , V. J. S. Bejar , J. A. Caballero , Th. Henning

Hot DA white dwarfs have fully radiative pure hydrogen atmospheres that are the least complicated to model. Pulsationally stable, they are fully characterized by their effective temperature Teff, and surface gravity log g, which can be…

Brown dwarfs are compact objects that do not reach temperatures high enough to produce sustained hydrogen fusion. Consequently, they cool over time, gradually evolving through later spectral types. In fact, three new spectral types (L, T,…

Solar and Stellar Astrophysics · Physics 2026-05-20 A. R. Callen , I. H. Bustos Fierro , M. Gómez

We report on a comparison of spectroscopic analyses for hydrogen (DA) and helium atmosphere (DB) white dwarfs with Gaia Data Release 2 (DR2) parallaxes and photometry. We assume a reddening law and a mass-radius relation to connect the…

Solar and Stellar Astrophysics · Physics 2018-11-28 P. -E. Tremblay , E. Cukanovaite , N. P. Gentile Fusillo , T. Cunningham , M. Hollands

A detailed analysis of the very cool white dwarfs SDSS 1337+00 and LHS 3250 is presented. Model atmosphere calculations with improved collision-induced absorptions by molecular hydrogen indicate that a pure hydrogen composition can be ruled…

Astrophysics · Physics 2008-11-26 P. Bergeron , S. K. Leggett

With the prevalence of wide-field, time-domain photometric sky surveys, the number of eclipsing white dwarf systems being discovered is increasing dramatically. An efficient method to follow these up will be key to determining any…

We present a near-infrared spectrum of the hot ($T_{\rm eff}$ $\approx$ 55,000 K) DA white dwarf PG 1234+482. We confirm that a very low mass companion is responsible for the previously recognised infrared photometric excess. We compare…

Astrophysics · Physics 2009-11-13 P. R. Steele , M. R. Burleigh , P. D. Dobbie , M. A. Barstow

We present a critical review of the determination of fundamental parameters of white dwarfs discovered by the Gaia mission. We first reinterpret color-magnitude and color-color diagrams using photometric and spectroscopic information…

Solar and Stellar Astrophysics · Physics 2019-05-15 P. Bergeron , P. Dufour , G. Fontaine , S. Coutu , S. Blouin , C. Genest-Beaulieu , A. Bédard , B. Rolland
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