2014A&A...567A.143L


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.10CEST02:54:11

2014A&A...567A.143L - Astronomy and Astrophysics, volume 567A, 143-143 (2014/7-1)

Abundance analysis for long-period variables. II. RGB and AGB stars in the globular cluster 47 Tucanae.

LEBZELTER T., NOWOTNY W., HINKLE K.H., HOEFNER S. and ARINGER B.

Abstract (from CDS):

Asymptotic giant branch (AGB) stars play a key role in the enrichment of galaxies with heavy elements. Due to their large amplitude variability, the measurement of elemental abundances is a highly challenging task that has not been solved in a satisfactory way yet. Following our previous work we use hydrostatic and dynamical model atmospheres to simulate observed high-resolution near-infrared spectra of 12 variable and non-variable red giants in the globular cluster 47Tuc. The 47Tuc red giants are independently well-characterized in important parameters (mass, metallicity, luminosity). The principal aim was to compare synthetic spectra based on the dynamical models with observational spectra of 47Tuc variables. Assuming that the abundances are unchanged on the upper giant branch in these low-mass stars, our goal is to estimate the impact of atmospheric dynamics on the abundance determination. To estimate abundances, we measured the equivalent widths of selected features in observed spectra and compared the results with predictions from a set of hydrostatic and dynamical model atmospheres resembling 47Tuc AGB stars in their fundamental parameters. Our study includes lines of 12CO, 13CO, OH, and Na. Furthermore, we investigated the variations in line intensities over a pulsation cycle. We present new measurements of the C/O and 12C/13C ratio for 5 non-variable red giants in 47Tuc. The equivalent widths measured for our 7 variable stars strongly differ from the non-variable stars and cannot be reproduced by either hydrostatic or dynamical model atmospheres. Nevertheless, the dynamical models fit the observed spectra of long-period variables much better than any hydrostatic model. For some spectral features, the variations in the line intensities predicted by dynamical models over a pulsation cycle give similar values as a sequence of hydrostatic models with varying temperature and constant surface gravity. Our study of the dynamical effects on abundance determination visible in these well-characterized cluster stars prepares the ground for the long-term goal of deriving abundances for variable AGB stars in general.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: late-type - stars: atmospheres - stars: abundances - line: profiles

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Cl* NGC 104 LW 1 V* 00 23 22.3384903907 -72 05 39.898734990     11.83     ~ 4 0
2 Cl* NGC 104 LEE 1603 * 00 23 23.0 -72 04 24   13.47 11.89     ~ 9 0
3 Cl* NGC 104 HH 9085 * 00 23 23.0 -72 04 24   13.58 12.15     ~ 10 0
4 Cl* NGC 104 HH 9083 * 00 23 23.0 -72 04 24   13.65 12.13     ~ 9 0
5 Cl* NGC 104 LEE 2426 * 00 23 23.0 -72 04 24   13.62 12.10     ~ 8 0
6 Cl* NGC 104 LEE 4603 * 00 23 23 -72 04.4   13.54 12.13     ~ 6 0
7 2MASS J00232921-7206204 V* 00 23 29.21 -72 06 20.4     11.90     ~ 3 0
8 Cl* NGC 104 LW 3 V* 00 23 47.3842503544 -72 06 52.698428633     11.92     ~ 4 0
9 Cl* NGC 104 R 79 V* 00 23 51.2540124802 -72 03 49.055106097   13.47 11.70     K2II 8 0
10 2MASS J00235692-7205325 RG* 00 23 56.9335581331 -72 05 32.558886305   13.398 11.775   9.858 ~ 7 0
11 2MASS J00240317-7204507 LP* 00 24 03.1673780500 -72 04 50.671132984   13.475 11.465   10.086 ~ 6 0
12 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3548 0
13 Cl* NGC 104 LW 18 V* 00 24 20.5349881204 -72 04 49.670770196     11.91     ~ 4 0
14 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14832 1
15 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2133 0

    Equat.    Gal    SGal    Ecl

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2020.07.10-02:54:11

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