EDP Sciences
Free Access
Issue
A&A
Volume 401, Number 3, April III 2003
Page(s) 1119 - 1129
Section Formation and evolution of planetary systems
DOI https://doi.org/10.1051/0004-6361:20030191


A&A 401, 1119-1129 (2003)
DOI: 10.1051/0004-6361:20030191

An analysis of the optical spectra of the post-asymptotic giant branch stars LSIV -12 111 and HD 341617

R. S. I. Ryans1, P. L. Dufton1, C. J. Mooney1, W. R. J. Rolleston1, F. P Keenan1, I. Hubeny2, 3 and T. Lanz2, 4

1  The Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, Northern Ireland
2  Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Centre, Greenbelt, MD 20771, USA
3  National Optical Astronomy Observatories, Tucson, AZ 85726, USA
4  Department of Astronomy, University of Maryland, College Park, MD 20742, USA

(Received 23 August 2002 / Accepted 4 February 2003)

Abstract
High spectral resolution and signal-to-noise observations of the absorption and emission line spectra in two post-asymptotic-giant-branch (PAGB) stellar candidates, LSIV -12 111 and HD 314617 are discussed. The absorption line spectra have been analysed using non-LTE model atmosphere techniques to determine stellar atmospheric parameters and chemical compositions, both in absolute terms and relative to a standard star, HD 13841. The atmospheric parameters differ from previous estimates based on LTE model atmospheres, probably due to non-LTE effects. In turn these imply stellar masses that are generally larger than have been previously estimated. Both PAGB candidates have relative uniform underabundances of metals with mean values of -0.35 dex for LSIV -12 111 and -0.50 dex for HD 314617.

Furthermore, their abundance patterns are remarkably similar to that observed for optically bright, F-type PAGBs. From the emission spectra, the plasma parameters and angular size of the circumstellar material are constrained, and these are consistent with previous estimates and with a PAGB evolutionary stage.


Key words: stars: abundances -- stars: supergiants -- stars: early-type -- stars: fundamental parameters

Offprint request: R. Ryans, R.Ryans@qub.ac.uk

SIMBAD Objects



© ESO 2003

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.