English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present a comprehensive analysis of DB white dwarfs drawn from the SloanDigital Sky Survey, based on model fits to $ugriz$ photometry and mediumresolution spectroscopy from the SDSS. We also take advantage of the exquisitetrigonometric parallax measurements recently obtained by the Gaia mission.Using the so-called photometric and spectroscopic techniques, we measure theatmospheric and physical parameters of each object in our sample ($T_{\rmeff}$, $\log g$, H/He, Ca/He, $R$, $M$), and compare the values obtained fromboth techniques in order to assess the precision and accuracy of each method.We then explore in great detail the surface gravity, stellar mass, and hydrogenabundance distributions of DB white dwarfs as a function of effectivetemperature. We present some clear evidence for a large population ofunresolved double degenerate binaries composed of DB+DB and even DB+DA whitedwarfs. In the light of our results, we finally discuss the spectral evolutionof DB white dwarfs, in particular the evolution of the DB-to-DA ratio as afunction of $T_{\rm eff}$, and we revisit the question of the origin ofhydrogen in DBA white dwarfs.

A Photometric and Spectroscopic Investigation of the DB White Dwarf Population using SDSS and Gaia Data