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| Paper: |
Calibrating the Role of TP-AGB Stars in the Cosmic Matter Cycle |
| Volume: |
497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time |
| Page: |
229 |
| Authors: |
Marigo, P. |
| Abstract: |
In the last ten years three main facts about the thermally pulsing
asymptotic giant branch (TP-AGB) have become evident: 1) the modelling
of the TP-AGB phase is critical for the derivation of basic galaxy
properties (e.g. mass and age) up to high redshift, with consequent
cosmological implications; 2) current TP-AGB calibrations based on
Magellanic Cloud (MC) clusters turn out not to work properly for other
external galaxies, yielding a likely TP-AGB overestimation; and 3)
the significance of the TP-AGB contribution in galaxies, and hence
their derived properties, are strongly debated, with conflicting claims
in favor of either a heavy or a light TP-AGB.
The only way out of this condition of persisting uncertainty is to
perform a reliable calibration of the TP-AGB phase as a function of
the star's initial mass (hence age) over a wide range of metallicity,
from very low to super-solar values. In this context, I will review
recent advances and ongoing efforts toward a physically-sound TP-AGB
calibration that, moving beyond the classical use of the MC clusters,
combines increasingly refined TP-AGB stellar models with exceptionally
high-quality data for resolved TP-AGB stars in nearby galaxies.
Preliminary results indicate that a sort of “TP-AGB island” emerges
in the age-metallicity plane, where the contribution of these stars
is especially developed, embracing preferentially solar- and MC-like
metallicities, and intermediate ages (a few Gyr). |
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