skip to main content

SciTech ConnectSciTech Connect

Title: QUIESCENT NUCLEAR BURNING IN LOW-METALLICITY WHITE DWARFS

We discuss the impact of residual nuclear burning in the cooling sequences of hydrogen-rich (DA) white dwarfs with very low metallicity progenitors (Z = 0.0001). These cooling sequences are appropriate for the study of very old stellar populations. The results presented here are the product of self-consistent, fully evolutionary calculations. Specifically, we follow the evolution of white dwarf progenitors from the zero-age main sequence through all the evolutionary phases, namely the core hydrogen-burning phase, the helium-burning phase, and the thermally pulsing asymptotic giant branch phase to the white dwarf stage. This is done for the most relevant range of main-sequence masses, covering the most usual interval of white dwarf masses—from 0.53 M {sub ☉} to 0.83 M {sub ☉}. Due to the low metallicity of the progenitor stars, white dwarfs are born with thicker hydrogen envelopes, leading to more intense hydrogen burning shells as compared with their solar metallicity counterparts. We study the phase in which nuclear reactions are still important and find that nuclear energy sources play a key role during long periods of time, considerably increasing the cooling times from those predicted by standard white dwarf models. In particular, we find that for this metallicity and for whitemore » dwarf masses smaller than about 0.6 M {sub ☉}, nuclear reactions are the main contributor to the stellar luminosity for luminosities as low as log (L/L {sub ☉}) ≅ –3.2. This, in turn, should have a noticeable impact in the white dwarf luminosity function of low-metallicity stellar populations.« less
Authors:
;  [1] ;  [2]
  1. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata (Argentina)
  2. Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, E-08860 Castelldefels (Spain)
Publication Date:
OSTI Identifier:
22215436
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 775; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMPTOTIC SOLUTIONS; COOLING; HELIUM BURNING; HYDROGEN; HYDROGEN BURNING; LUMINOSITY; MASS; NUCLEAR ENERGY; NUCLEAR REACTIONS; STAR EVOLUTION; WHITE DWARF STARS