Issue |
A&A
Volume 378, Number 2, November I 2001
|
|
---|---|---|
Page(s) | 455 - 465 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20011210 | |
Published online | 15 November 2001 |
K 413, a star near the AGB in the globular cluster M 12
1
Special Astrophysical Observatory, N. Arkhyz 369167, Russia
2
Isaac Newton Institute of Chile, SAO Branch, Russia
3
Institute of Astronomy of Russian Acad. Sci., 48, Pyatnitskaya Str., Moscow 109017, Russia and Sternberg Astronomical Institute of Moscow University, 13, University Ave., Moscow 119899, Russia
4
Isaac Newton Institute of Chile, Moscow Branch, Russia
Corresponding author: V. G. Klochkova, valenta@sao.ru
Received:
27
June
2001
Accepted:
20
August
2001
CCD spectra obtained with the echelle spectrometer of
the 6-meter telescope were used to determine, by the model
atmospheres method, the fundamental parameters
( = 4800 K, log ) and detailed chemical
abundances for the star K 413, a member of the globular cluster
M 12. The resulting value,
, is
the first metallicity determination for M 12 using
high-resolution spectra. The main characteristic feature
of the star's atmospheric chemical abundance pattern is a large oxygen
excess,
.
The s-process elements are probably slightly depleted compared to
metallicity:
for yttrium and
zirconium,
for barium. Abundances
of the heavier elements: La, Ce, Nd, and Pr, do not differ,
relative to iron, from the solar ones:
.
The europium excess,
, is
typical of members of low-metallicity globular clusters.
The spectrum of K 413 shows, for the Hα line, an variable
absorption and emission profile. From its high luminosity and
chemical abundance anomalies, we can suppose that K 413 is in an
evolutionary stage after the AGB. In the spectrum, we
find absorption details that can be identified with diffuse
interstellar bands displaced by 16 to longer wavelengths
relative to the star's velocity.
Key words: globular clusters: general / galaxy: globular clusters: individual: M 12 / stars: abundances / stars: atmospheres / stars: AGB and post-AGB
© ESO, 2001
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