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Diffusion in hot subdwarf progenitors from the common envelope channel

Published version
Peer-reviewed

Type

Article

Change log

Authors

Byrne, CM 
Jeffery, CS 
Tout, CA 
Hu, H 

Abstract

© 2017 C. M. Byrne et al. Diffusion of elements in the atmosphere of a star can drastically affect its surface composition, sometimes leading to unusual mixtures. These chemically peculiar stars can be identified from the presence of unusual lines in their spectra. Some hot subdwarf stars show extraordinary abundances of elements such as lead, zirconium and strontium, while the abundance of helium ranges from practically zero to almost 100 percent across the hot subdwarf population. A sequence of extreme horizontal branch star models was generated by producing a number of post-common envelope objects from red giants. The evolution of these subdwarf progenitors was computed with the MESA stellar evolution code from immediately after envelope ejection right up to the ignition of helium in the core. Envelope abundances were calculated at the zero age horizontal branch for models both with and without the presence of diffusion. A small number of simulations also looked at the effects on radiative levitation of these abundances, to test how well diffusion physics is able to reproduce observational data.

Description

Keywords

atomic processes, stars: evolution, stars: subdwarfs

Journal Title

Open Astronomy

Conference Name

Journal ISSN

2543-6376
2543-6376

Volume Title

26

Publisher

De Gruyter