A Grid of MARCS Model Atmospheres for S Stars
2011 (English)In: Astronomical Society of the Pacific, Conference Series, Volume 445, 2011, 71-75 p.Conference paper (Refereed)
S-type stars are late-type giants whose atmosphere is enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing AGB. A large grid of S-star model atmospheres has been computed covering the range 2700 < Teff < 4000 K with 0.5 < C/O < 0.99. ZrO and TiO band strength indices as well as VJHKL photometry are needed to disentangle Teff, C/O and [s/Fe]. A "best-model finding tool" was developed using a set of well-chosen indices and checked against photometry as well as low- and high-resolution spectroscopy. It is found that applying M-star model atmospheres (i.e., with a solar C/O ratio) to S stars can lead to errors on Teff up to 400K. We constrain the parameter space occupied by S stars of the vast sample of Henize stars in terms of Teff, [C/O] and [s/Fe].
Place, publisher, year, edition, pages
2011. 71-75 p.
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-169035OAI: oai:DiVA.org:uu-169035DiVA: diva2:504923
Why Galaxies Care about AGB Stars II: Shining Examples and Common Inhabitants