Exploring circumstellar effects on the lithium and calcium abundances in massive Galactic O-rich AGB stars

Abstract

We previously explored the circumstellar effects on the Rb and Zr abundances in massive Galactic O-rich AGB stars. Here we are interested in the role of the extended atmosphere in the case of Li and Ca. Li is an important indicator of HBB while the total Ca in these stars could be affected by neutron captures. The Li abundances were previously studied with hydrostatic models, while the Ca abundances have been determined for the first time. We use a modified version of Turbospectrum and consider the presence of a gaseous circumstellar envelope and radial wind. The new Li abundances derived with the pseudo-dynamical models are very similar to those obtained from hydrostatic models (the average difference is 0.18 dex), with no difference for Ca. The Li and Ca content in these stars is only slightly affected by the presence of a circumstellar envelope. We also found that the Li I and Ca I line profiles are not very sensitive to variations of the model wind parameters. The new Li abundances confirm the Li-rich nature of the sample stars, supporting the activation of HBB in massive Galactic AGB stars. This is in good agreement with the theoretical predictions for solar metallicity AGB models from ATON, Monash, and NuGrid/MESA but is at odds with the FRUITY database, which predicts no HBB leading to the production of Li. Most sample stars display nearly solar Ca abundances that are consistent with the available s-process nucleosynthesis models for solar metallicity massive AGB stars, which predict overproduction of 46Ca relatively to the other Ca isotope and the creation of the radiactive isotope 41Ca but no change in the total Ca abundance. A minority of the stars seem to show a significant Ca depletion (by up to 1.0 dex). Possible explanations are offered to explain their apparent and unexpected Ca depletion.

arXiv comment14 pages, 8 figures, accepted in A&A

References in corpus (40)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• Nucleosynthesis and mixing on the Asymptotic Giant Branch. III. Predicted and observed s-process abundances
• Evolution, nucleosynthesis and yields of AGB stars at different metallicities (III): intermediate mass models, revised low mass models and the ph-FRUITY interface
• Stellar yields from metal-rich asymptotic giant branch models
• Stellar Models and Yields of Asymptotic Giant Branch Stars
• s Process in low-mass Asymptotic Giant Branch Stars
• Aluminum-, Calcium- And Titanium-Rich Oxide Stardust In Ordinary Chondrite Meteorites
• Massive AGB models of low metallicity: the implications for the self-enrichment scenario in metal poor Globular Clusters
• The Kr85 s-process Branching and the Mass of Carbon Stars
• NuGrid Stellar Data Set. II. Stellar Yields from H to Bi for Stellar Models with Mzams = 1 to 25Msun and Z = 0.0001 to 0.02
• Evolution and nucleosynthesis of asymptotic giant branch stellar models of low metallicity
• Rubidium-Rich Asymptotic Giant Branch Stars
• Radioactive nuclei from cosmochronology to habitability
• Lithium and zirconium abundances in massive Galactic O-rich AGB stars
• Heavy-element yields and abundances of Asymptotic Giant Branch models with a Small Magellanic Cloud metallicity
• Heavy Element Nucleosynthesis in the Brightest Galactic Asymptotic Giant Branch stars
• Line formation in AGB atmospheres including velocity effects. Molecular line profile variations of long period variables
• Dynamic atmospheres and winds of cool luminous giants, I. Al${}_2$O${}_3$ and silicate dust in the close vicinity of M-type AGB stars
• Rubidium, zirconium, and lithium production in intermediate-mass asymptotic giant branch stars
• Construction of a Calibrated Probabilistic Classification Catalog: Application to 50k Variable Sources in the All-Sky Automated Survey
• Rb-rich Asymptotic Giant Branch stars in the Magellanic Clouds
• ExoMol molecular line lists - XIII: The spectrum of CaO
• Stellar origin of the 182Hf cosmochronometer and the presolar history of solar system matter
• Synthetic photometry for carbon-rich giants. IV. An extensive grid of dynamic atmosphere and wind models
• Hot bottom burning and s-process nucleosynthesis in massive AGB stars at the beginning of the thermally-pulsing phase
• Abundances in intermediate-mass AGB stars undergoing third dredge-up and hot-bottom burning
• Mg line formation in late-type stellar atmospheres: II. Calculations in a grid of 1D models
• The Local Group Galaxy IC1613 and its Asymptotic Giant Branch Variables
• Short-lived radioactivity in the early Solar System: the Super-AGB star hypothesis
• The Role of Massive Agb Stars in the Early Solar System Composition
• On the alumina dust production in the winds of O-rich Asymptotic Giant Branch stars
• Circumstellar effects on the Rb abundances in O-rich AGB stars
• Spitzer/IRS spectroscopy of high mass precursors to planetary nebulae
• Ca line formation in late-type stellar atmospheres: I. The model atom
• Determination of the stellar (n,gamma) cross section of 40Ca with accelerator mass spectrometry
• Isotope Anomalies in the Fe-group Elements in Meteorites and Connection to Nucleosynthesis in AGB Stars
• Rubidium and zirconium abundances in massive Galactic asymptotic giant branch stars revisited
• Near-IR variability properties of a selected sample of AGB stars
• Radioactivities in Low- and Intermediate-Mass Stars

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