| 1. |
- Pastorelli, Giada, et al.
(författare)
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Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
- 2020
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 498:3, s. 3283-3301
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Tidskriftsartikel (refereegranskat)abstract
- Reliable models of the thermally pulsing asymptotic giant branch (TP-AGB) phase are of critical importance across astrophysics, including our interpretation of the spectral energy distribution of galaxies, cosmic dust production, and enrichment of the interstellar medium. With the aim of improving sets of stellar isochrones that include a detailed description of the TP-AGB phase, we extend our recent calibration of the AGB population in the Small Magellanic Cloud (SMC) to the more metal-rich Large Magellanic Cloud (LMC). We model the LMC stellar populations with the TRILEGAL code, using the spatially resolved star formation history derived from the VISTA survey. We characterize the efficiency of the third dredge-up by matching the star counts and the K-s-band luminosity functions of the AGB stars identified in the LMC. In line with previous findings, we confirm that, compared to the SMC, the third dredge-up in AGB stars of the LMC is somewhat less efficient, as a consequence of the higher metallicity. The predicted range of initial mass of C-rich stars is between M-i approximate to 1.7 and 3 M-circle dot at Z(i) = 0.008. We show how the inclusion of new opacity data in the carbon star spectra will improve the performance of our models. We discuss the predicted lifetimes, integrated luminosities, and mass-loss rate distributions of the calibrated models. The results of our calibration are included in updated stellar isochrones publicly available.
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| 2. |
- Pawlak, Michał, et al.
(författare)
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Investigating the long secondary period phenomenon with the ASAS-SN and Gaia data
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361. ; 682
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Tidskriftsartikel (refereegranskat)abstract
- Aims. The aim of this work is to create a complete list of sources exhibiting a long secondary period (LSP) in the ASAS-SN catalog of variable stars, and analyze the properties of this sample compared to other long period variables without an LSP. Methods. We used the period-amplitude diagram to identify the 55 572 stars showing an LSP, corresponding to 27% of the pulsating red giants in the catalog. We used astrometric data from Gaia DR3 and spectroscopic data provided by the APOGEE, GALAH, and RAVE surveys to investigate the statistical properties of the sample. Results. We find that stars displaying an LSP have a spatial distribution that is more dispersed than that of the non-LSP giants, suggesting that they belong to an older population. Spectroscopically derived ages seem to confirm this. The stars with an LSP also appear to be different in terms of the C/O ratio from their non-LSP counterparts.
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