White Dwarfs: Proceedings of the 10th European Workshop on White Dwarfs, held in Blanes, Spain, 17–21 June 1996

ISBN-13: 9789401063340 / Angielski / Miękka / 2012 / 492 str.

J. Isern;M. Hernanz;E. García-Berro

Opis

The study of white dwarfs has been steadily growing during the last years and now is a mature field extending its influence over many others. Since white dwarfs are long lived objects, they can be used to obtain information about the history of the Galaxy. The simplicity of their structures enables them to act as precise particle physics laboratories and the extreme con- ditions reached at their surfaces allow us to test the equation of state and to study the behavior of matter under conditions impossible to be reached in terrestrial laboratories. Nevertheless, white dwarfs are still challenging astrophysicists. Many questions, ranging from the determination of funda- mental parameters to the evolution of their outer layers, are still waiting for a satisfactory answer. The European Workshop series on White Dwarfs started in 1974 as a con- sequence of the effort and enthusiasm of Professor Volker Weidemann. The existing proceedings of these meetings, together with those corresponding to the lAU Colloquia held in Rochester (1979) and in Hanover (1988), provide a unique opportunity to follow the development of this field. We hope that the present volume will provide a representative snapshot of the state of the art in 1996. In this sense we are very indebted to all the participants that have sent their contributions according to the instructions (this clearly excludes everybody beyond three sigmas from the standards).

Spis treści

I. Structure and Evolution.- The empirical white dwarf mass-radius relation.- What we have learned about white dwarfs from studies of novae.- The redistribution of carbon and oxygen in crystallizing white dwarfs.- The cooling of white dwarfs and their internal composition.- Theoretical models of white dwarfs with helium-rich interiors.- The electrostatic screening of thermonuclear reactions in astrophysical plasmas.- The possible white dwarf-neutron star connection.- The impact of evolutionary envelope masses on the evolution of white dwarfs.- The progenitors of high-mass white dwarfs.- The multiperiodic, short-period variations of WZ Sge.- Limits on gravities of evolved stars, from infrared photometry and binary companions.- Rotation: CO white dwarfs near the Chandrasekhar limiting mass.- The Accretion-Induced Collapse of white dwarfs revisited in 3D.- II. Luminosity Functions and Populations.- Towards a luminosity function of hot DA white dwarfs.- White dwarfs in M67.- Monte Carlo simulations of the kinematics and luminosity function of white dwarfs.- Monte Carlo simulations of the white dwarf population and luminosity function.- Halo white dwarfs: a conservative point of view.- Halo white dwarfs: a non conventional scenario.- HST observations of white dwarfs in the globular cluster NGC 6397.- The distance and age of the globular cluster NGC 6752 measured by HST observations of cluster and field white dwarfs.- DA white dwarfs in the Montréal-Cambridge-Tololo survey.- Cool white dwarf survey using stacked digitised Schmidt plates.- III. Atmospheres.- Chemical evolution of cool white dwarf’s atmospheres.- The chemical evolution of white dwarf stars: what the observations tell us.- A critical look at the question of thick vs thin hydrogen and helium envelopes in white dwarfs.- Polyatomic carbon molecules in very cool helium-rich white dwarfs.- Analysis of optical, UV and EUV observations of G 191-B2B.- New results on PG 1159 stars and ultrahigh-excitation DO white dwarfs.- Non-LTE analyses of DO white dwarfs.- New spectral analyses of pre-white dwarfs.- The sphericity effects in the NLTE model atmospheres of white dwarfs.- Heavy elements in white dwarf envelopes.- Lyman spectra of hot DA white dwarfs.- Diffusion of silicon in the envelopes of hot DA white dwarfs.- Time-dependent diffusion calculations for hot pre-white dwarfs.- Evolutionary calculations of carbon dredge-up in helium envelope white dwarfs.- Analysis of optical and ultraviolet spectroscopy of the DAZ white dwarf G 74–7.- Modeling extreme ultraviolet spectra of white dwarfs with high-metallicity LTE models.- Extreme ultraviolet spectroscopy of EUVE J0720-317 and EUVE J0723-277.- A new dithered EUVE spectrum of PG 1234+482.- Line of sight H and He ionization fractions in the local interstellar medium.- An instrument for observations of EUV opacity sources in G 191-B2B.- Metals in the variable DA G 29–38.- IV. White Dwarfs in Binaries.- In search of the double degenerate progenitors of Type Ia Supernovae.- The double degenerate population.- White dwarf+M dwarf systems: a new infrared search.- The EC 14026 stars: a new class of pulsating star.- Hot white dwarfs in non-interacting binaries from the ROSAT EUV survey.- HST observations of AM Canum Venaticorum.- Effects of irradiation on the secondary star in a tight binary system, exemplified by AM Canum Venaticorum.- White dwarfs in AM Herculis systems.- HST synthetic spectral analysis of U Gem in early and late quiescence: a heated white dwarf and accretion belt.- WFPC2 observations of Procyon B.- Extreme ultraviolet light curve and phase-resolved spectroscopy of the hot white dwarf in V 471 Tauri.- Unique white dwarfs accompanying recycled pulsars.- Merging of different mass ratio white dwarfs: first moments of the 0.4–1.2 M? case.- V. Magnetic White Dwarfs.- New results of magnetic white dwarf spectroscopy.- 1-D and 2-D calculations of dynamo-generated magnetic fields in white dwarfs.- Magnetic field survey of DC white dwarfs.- New IUE-spectra of the magnetic white dwarf Grw +70°8247 and their interpretation.- VI. Pulsating White Dwarfs.- Convection and the ZZ Ceti instability strip.- WET observations of the DAV variable HL Tau 76: first results.- Preliminary asteroseismology of G 29–38.- Recent advances in the theoretical determination of the ZZ Ceti instability strip.- Cool DAV asteroseismology.- Overstability of g-modes in ZZ Ceti variables.- A continuing spectroscopic study of the instability strip of the pulsating DB (V 777 Her) white dwarfs: the view in the optical.- The potential of asteroseismology for hot, B subdwarfs: a new class of pulsating stars?.- Modeling time-resolved spectra of ZZ Ceti stars.- Discovery of two new ZZ Ceti variables.- Non-pulsating DA white dwarfs in the DAV region.