Speaker
Kaori Otsuki
(University of Chicago)
Description
We report on observations of six giants in the globular cluster M15 (NGC 7078).
The Subaru/HDS was used to measure neutron-capture elemental abundances.
Previous studies have reported a significant star-to-star variation in the
neutron-capture elemental abundances of M15, and deduced that their origin was from
the r-process. Our abundance analyses based on high-quality blue spectra confirm the
scatter in the abundances of heavy neutron-capture elements (e.g., Eu). Observed
[La/Eu] ratios indicate there are no significant s-process contributions.
We have found, for the first time, that there are anti-correlations between the
abundance ratios of light to heavy neutron-capture elements ([Y/Eu] and [Zr/Eu])
and heavy ones (e.g., Eu). This indicates that light neutron-capture elements in
these stars cannot be explained by only a single r-process, but another process that
has significantly contributed to the light neutron-capture elements is required to
have occurred in M15. We will also discuss possible r-process enrichment model to
explain our results.
Author
Kaori Otsuki
(University of Chicago)
Co-authors
Anibal Medina
(University of Chicago)
Prof.
Grant Mathews
(University of Notre Dame)
Prof.
Jim Truran
(University of Chicago)
Dr
Satoshi Honda
(National Astronomical Observatory of Japan)
Prof.
Toshitaka Kajino
(National Astronomical Observatory of Japan)
Vikram Dwarkadas
(University of Chicago)
Dr
Wako Aoki
(National Astronomical Observatory of Japan)
