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| Paper: |
Exploring the Onset of the Contribution of the First AGB Stars
to the Galactic Chemical Enrichment using Isotopic Ratios |
| Volume: |
497, Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time |
| Page: |
523 |
| Authors: |
Goswami, A. |
| Abstract: |
There is uncertainty over the time at which the first intermediate
and low-mass stars reach the AGB phase and begin to influence their
environments with the products of nucleosynthesis. While some studies
have indicated that enrichment from AGB stars sets in at a time
corresponding to –2.4 < [Fe/H] < –2.1, others suggest a
time as early as [Fe/H] ≈ –2.75. These suggestions come
from observations of s-process heavy elements in old metal-poor stars.
Measurements of stellar isotopic ratios, such as the Mg isotope ratios,
can also be a useful probe to explore the
contribution of AGB stars to the Galactic chemical inventory. However,
measurements of isotopic ratios require spectra with high resolution
(R > 90 000) and high S/N ratios (> 200) which require very long
exposure times with the existing observing facilities. Upcoming large
telescopes of 25 to 42-m size equipped with high resolution spectrographs
will provide the resolution and sensitivity required for measurements of
isotopic ratios that are fundamental indicators of nucleosynthesis. |
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