Abstract
view Abstract Citations (154) References (48) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Carbon Pollution in Helium-rich White Dwarf Atmospheres: Time-dependent Calculations of the Dredge-up Process Pelletier, C. ; Fontaine, G. ; Wesemael, F. ; Michaud, G. ; Wegner, G. Abstract Calculations are presented showing that carbon diffusing upward from the core can contaminate the atmospheres of cooling He-rich white dwarfs, a process which provides a natural explanation for the presence of traces of carbon in the spectra of such stars. The computations explicitly couple diffusion and evolution, include the effects of electron degeneracy on the carbon distribution, and take into account the variable ionization state of carbon. Maximum contamination occurs at temperatures around 12,000 K, approximately the effective temperature at which the base of the helium convection zone reaches its maximum depth. Below this temperature, carbon pollution decreases with further cooling, largely because carbon sinks back into the star due to its partial recombination. The sensitivity of the theoretical results to changes in helium layer mass, stellar mass, efficiency of turbulent transport, and convective efficiency is investigated. Publication: The Astrophysical Journal Pub Date: August 1986 DOI: 10.1086/164410 Bibcode: 1986ApJ...307..242P Keywords: Carbon; Stellar Atmospheres; Stellar Composition; Stellar Models; White Dwarf Stars; Abundance; Atmospheric Composition; Atmospheric Diffusion; Helium; Stellar Mass; Time Dependence; Astrophysics; DIFFUSION; STARS: ABUNDANCES; STARS: INTERIORS; STARS: WHITE DWARFS full text sources ADS |
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