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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Hot subdwarf B stars (sdBs) are core helium-burning stars located on theextreme horizontal branch. About half of the known sdB stars are found in closebinaries. Their short orbital periods of 1.2 h to a few days suggest that theyare post common-envelope systems. Eclipsing hot subdwarf binaries are rare, butimportant to determine the fundamental stellar parameters. Low-mass companionsare identified by the reflection effect. In most cases the companion is a mainsequence star near the stellar mass limit. Here we report the discovery of aneclipsing hot subdwarf binary SDSS J162256.66+473051.1 (J1622) of very shortorbital period (0.0697 d), found in the course of the MUCHFUSS project. Thelightcurve shows grazing eclipses and a prominent reflection effect. Ananalysis of the light- and radial velocity (RV) curves indicated a mass ratioof $q=$ 0.1325, an RV semiamplitude $K=47.2\rm\,km\,s^{-1}$, and an inclinationof $i=72.33^\circ$. We show that a companion mass of 0.064 $M_{\rm \odot}$,well below the hydrogen-burning limit, is the most plausible solution, whichimplies a mass close to the canonical mass (0.47 $M_{\rm \odot}$) of the sdBstar. Therefore, the companion is a brown dwarf, which not only survived theengulfment by the red-giant envelope, but also triggered its ejection, andenabled the sdB star to form. The rotation of J1622 is expected to be tidallylocked to the orbit. However, J1622 rotates too slowly ($v_{\rm rot}=74.5\pm7\rm\,km\,s^{-1}$) to be synchronized, challenging tidal interaction models.

Binaries discovered by the MUCHFUSS project: SDSS J162256.66$+$473051.1 - An eclipsing subdwarf B binary with a brown dwarf companion