A study of metal abundance patterns in cool white dwarfs. I - Time-dependent calculations of gravitational settling

Abstract

view Abstract Citations (96) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Study of Metal Abundance Patterns in Cool White Dwarfs. I. Time-dependent Calculations of Gravitational Settling Dupuis, J. ; Fontaine, G. ; Pelletier, C. ; Wesemael, F. Abstract The process of gravitational settling of Mg, Si, Ca, and Fe in models of cool white dwarfs are discussed. The evolution of the distribution of these metals over 25 orders of magnitude in abundance is examined for both static models and models incorporating the effects of cooling as function of time. It is shown that the behavior of the surface abundance of a given metal follows an exponential law very closely. The behavior of the abundance at a given radiative shell below the superficial convection zone is, however, quite different from an exponential law. It is confirmed that the primordial heavy elements can only leave negligible traces in the surface layers of a white dwarf, and that there is a need for an extrinsic source of metals in cool white dwarfs. It is also found that settling of heavy elements freezes over the inner 99-99.9 percent of the mass of a white dwarf, which may have significant impact on the computation of cooling time scales. Publication: The Astrophysical Journal Supplement Series Pub Date: October 1992 DOI: 10.1086/191728 Bibcode: 1992ApJS...82..505D Keywords: Abundance; Cool Stars; Gravitational Effects; Metallicity; White Dwarf Stars; Heavy Elements; Stellar Evolution; Stellar Models; Astrophysics; DIFFUSION; STARS: ABUNDANCES; STARS: WHITE DWARFS full text sources ADS | data products SIMBAD (3) Related Materials (2) Part 2: 1993ApJS...84...73D Part 3: 1993ApJS...87..345D