Speaker
Ms
Erika Holmbeck
(University of Notre Dame)
Description
Metal-poor stars in the Galactic halo have been studied for the past half century in order to understand the chemical evolution of the Galaxy, extending back to the first generations of stars born in the Universe. However, only within the last twenty years have very metal-poor, highly r-process-element-enhanced (r-II) stars begun to shed light on the cosmic origin of the r-process elements. Herein we present the first r-II star found within the RAVE survey (RAVE J2038-0023; a bright, non-carbon-enhanced star with V = 12), following medium- and high-resolution spectroscopic follow-up with the KPNO/Mayall and Magellan Telescopes, respectively. An initial analysis indicates that this star, with [Fe/H] = –2.8, lies within the metallicity range typical of r-II stars, and that it is strongly enhanced in neutron-capture elements (Eu/Fe] = +1.85). High-resolution follow-up has confirmed the presence of the actinides Th and U (this star is only the fourth very metal-poor star known with clearly detected U). We will present a full chemical abundance analysis for this star, as well as a comparison with current theoretical yields for the r-process. Ongoing efforts to identify additional r-II halo field stars, described here as well, will provide critical constraints on the astrophysical site of the r-process.
Primary author
Ms
Erika Holmbeck
(University of Notre Dame)
Co-authors
Prof.
Anna Frebel
(Massachusetts Institute of Technology)
Dr
Charli Sakari
(University of Washington)
Prof.
Rebecca Surman
(University of Notre Dame)
Prof.
Timothy Beers
(University of Notre Dame)
Dr
Vinicius Placco
(University of Notre Dame)
