Physical Sciences and Mathematics Commons^™

The Helium-Rich Subdwar Cpd-20d1123: A Post-Common-Envelope Binary Evolving On To The Extended Horizontal Branch, Vincent M. Woolf

Vincent M Woolf

Subluminous B stars come in a variety of flavours including single stars, close and wide binaries, and pulsating and non-pulsating variables.

We present a fine analysis of the bright intermediate helium sdB star CPD-20d1123 which shows it to be cool, for a hot subdwarf, with Teff = 23000 K and with a surface helium abundance ~17 percent by number. Other elements do not show extraordinary anomalies; in common with majority sdB stars, carbon and oxygen are substantially depleted, whilst nitrogen is enriched. Magnesium through sulphur appear to be depleted by ~0.5 dex, but chlorine and argon are substantially enhanced.

We …