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| Paper: |
A Grid of MARCS Model Atmospheres for S Stars |
| Volume: |
445, Why Galaxies Care about AGB Stars II: Shining Examples and Common Inhabitants |
| Page: |
71 |
| Authors: |
Van Eck, S.; Neyskens, P.; Plez, B.; Jorissen, A.; Edvardsson, B.; Eriksson, K.; Gustafsson, B.; Jørgensen, U. G.; Nordlund, Å. |
| Abstract: |
S-type stars are late-type giants whose atmospheres are 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(K) ≤ 4000 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” has been 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 in Teff up to 400 K.
We constrain the parameter space occupied by the S stars of the vast Henize sample in terms of Teff, [C/O] and [s/Fe]. |
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