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 EVR-CB-001, the discovery of a compact binary with an extremelylow mass ($.21 \pm 0.05 M_{\odot}$) helium core white dwarf progenitor (pre-HeWD) and an unseen low mass ($.32 \pm 0.06 M_{\odot}$) helium white dwarf (HeWD) companion. He WDs are thought to evolve from the remnant helium-rich coreof a main-sequence star stripped during the giant phase by a close companion.Low mass He WDs are exotic objects (only about .2$\%$ of WDs are thought to beless than .3 $M_{\odot}$), and are expected to be found in compact binaries.Pre-He WDs are even rarer, and occupy the intermediate phase after the core isstripped, but before the star becomes a fully degenerate WD and with a largerradius ($\approx .2 R_{\odot}$) than a typical WD. The primary component ofEVR-CB-001 (the pre-He WD) was originally thought to be a hot subdwarf (sdB)star from its blue color and under-luminous magnitude, characteristic of sdBs.The mass, temperature ($T_{\rm eff}=18,500 \pm 500 K$), and surface gravity($\log(g)=4.96 \pm 0.04$) solutions from this work are lower than values fortypical hot subdwarfs. The primary is likely to be a post-RGB, pre-He WDcontracting into a He WD, and at a stage that places it nearest to sdBs oncolor-magnitude and $T_{\rm eff}$-$\log(g)$ diagrams. EVR-CB-001 is expected toevolve into a fully double degenerate, compact system that should spin down andpotentially evolve into a single hot subdwarf star. Single hot subdwarfs areobserved, but progenitor systems have been elusive.

EVR-CB-001: An evolving, progenitor, white dwarf compact binary discovered with the Evryscope