Evidence of Spectral Evolution on the white dwarf sample from the Gaia Mission

Abstract

Since the Gaia data release 2, several works were published describing a bifurcation in the observed white dwarf colour$-$magnitude diagram for $\mbox{$G_{\mathrm{BP}}$}-\mbox{$G_{\mathrm{RP}}$} > 0$. Some possible explanations in the literature include the existence of a double population with different initial mass function or two distinct populations, one formed by hydrogen$-$ and one formed by helium$-$envelope white dwarfs. We propose instead spectral evolution to explain the bifurcation. From a population synthesis approach, we find that the spectral evolution occurs for effective temperature below $\simeq 11000\mathrm{K}$ and masses mainly between $0.64{\mathrm{M}}_{\odot }$ and $0.74{\mathrm{M}}_{\odot }$, which correspond to around $16$ per cent of all DA white dwarfs. We also find the Gaia white dwarf colour-magnitude diagram indicates a star formation history that decreases abruptly for objects younger than $1.4\mathrm{Gyr}$ and a top-heavy initial mass function for the white dwarf progenitors.

9 pages, 9 figures, accepted by MNRAS

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Cited by in corpus (8)

• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• The 40 pc sample of white dwarfs from Gaia
• Spectral classification of the 100 pc white dwarf population from Gaia-DR3 and the Virtual Observatory
• Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS
• The spectral evolution of white dwarfs: where do we stand?
• A hidden population of white dwarfs with atmospheric carbon traces in the Gaia bifurcation
• White dwarf spectral type-temperature distribution from Gaia-DR3 and the Virtual Observatory
• Asteroseismology of PG 1541$+$651 and BPM 31594 with TESS