J/A+A/583/A56 Abundance study of two LMC post-AGB stars (De Smedt+, 2015)
Chemical abundance study of two strongly s-process enriched post-AGB stars
in the LMC: J051213.81-693537.1 and J051848.86-700246.9.
De Smedt K., Van Winckel H., Kamath D., Wood P.R.
<Astron. Astrophys. 583, A56 (2015)>
=2015A&A...583A..56D 2015A&A...583A..56D (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Abundances ; Spectroscopy
Keywords: stars: AGB and post-AGB - stars: abundances - stars: evolution -
Magellanic Clouds
Abstract:
This paper is part of a larger project in which we systematically
study the chemical abundances of extra-galactic post-asymptotic giant
branch (post-AGB) stars. The aim of our programme is to derive
chemical abundances of stars covering a large range in luminosity and
metallicity with the ultimate goal of testing, constraining, and
improving our knowledge of the poorly understood AGB phase, especially
the third dredge-up mixing processes and associated s-process
nucleosynthesis.
Post-AGB photospheres are dominated by atomic lines and indicate the
effects of internal chemical enrichment processes over the entire
stellar lifetime. In this paper, we study two carefully selected
post-AGB stars: J051213.81-693537.1 and J051848.86-700246.9 in the
Large Magellanic Cloud (LMC). Both objects show signs of s-process
enhancement. The combination of favourable atmospheric parameters for
detailed abundance studies and their known distances (and hence
luminosities and initial masses) make these objects ideal probes of
the AGB third dredge-up and s-process nucleosynthesis in that they
provide observational constraints for theoretical AGB models.
Description:
We used the UVES spectrograph mounted on the Very Large Telescope
(VLT) at the European Southern Observatory (ESO), to obtain
high-resolution spectra with high signal-to-noise (S/N) of two
post-AGB stars of the Large Magellanic Cloud. The spectral energy
distributions (SEDs) of the objects indicate the presence of
circumstellar dust. We perform an extensive detailed abundance
analysis on the basis of these spectra. Both catalogues have the same
layout: the identification is given by the proton-number of the
chemical element. For lines coming from ionised lines, we add 0.1 to
the proton number; the wavelength is given in rest in air in Angstrom
units; the excitation potential (eV); the used oscillator strength and
finally the measured equivalent width (mÅ).
Objects:
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RA (2000) DE Designation(s)
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05 12 13.81 -69 35 37.1 J051213.81-693537.1 = 2MASS J05121381-6935371
05 18 48.87 -70 02 47.0 J051848.86-700246.9 = 2MASS J05184886-7002469
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
j051213.dat 36 168 Linelist of J051213.81-693537.1
j051848.dat 36 169 Linelist of J051848.86-700246.9
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Byte-by-byte Description of file: j051213.dat j051848.dat
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Bytes Format Units Label Explanations
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1- 5 F5.1 --- Ion Identification:
Mass number+0.1*ionisation stage
7- 15 F9.3 0.1nm lambda Wavelength in rest frame (Å)
17- 22 F6.2 eV chi Excitation potential
24- 29 F6.2 [-] loggf Oscillator strength
31- 36 F6.1 0.1pm EW Equivalenth width (mÅ)
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Acknowledgements:
Kenneth De Smedt, Kenneth.DeSmedt(at)ster.kuleuven.be
(End) Patricia Vannier [CDS] 05-Aug-2015