There are no scheduled talks today.
Characterization of Planetary Atmospheres
Karan Molaverdikhani
Fri, 21 Jun 2019, 15:00
Fundamental Physics with High-Energy Cosmic Neutrinos
Dr. Mauricio Bustamante
Mon, 24 Jun 2019, 16:30
Lynton Ardizzone
Tue, 25 Jun 2019, 14:15

CEMP stars - a new way of obtaining metallicities and classifications

Camilla Hansen , MPIA
Carbon enhanced metal-poor (CEMP) stars are low-mass stars formed throughout the history of the Universe. They are found in various environments from dwarf galaxies, to more massive galaxies like the Milky Way. These carbon rich stars can occur as single, very old, possibly bona fide second generation stars, or in binary systems, but they also occur as variable RR Lyr stars. This class of stars is therefore important to understand, as one can trace the chemical environments at different times from the first low-mass stars that formed shortly after Big Bang up to today. The CEMP stars are subcategorised depending on their heavy element (Z>30) content, and they tend to show an enhancement in either slow or rapid neutron-capture elements (or both) or a complete lack of heavy elements. These CEMP stars are typically cool stars with strong molecular bands obliviating the usual chemical imprints from the smaller atomic absorption features. It is therefore challenging to analyse this class of stars. Here I will present a new way of deriving metallicities for CEMP stars as well as a new fast way of subclassifying the CEMP stars into their various subgroups, which in turn allows for a first assessment of their binary nature using single exposure low-to-medium resolution spectra (i.e., follow-up observations tracing radial velocity variations may not be needed). These new methods may prove highly relevant in the era of large surveys where a fast chemical analysis is sought after. Finally, I will use the heavy elements to trace the extinct sources that enriched the long-living CEMP stars.
ARI Institute Colloquium
10 Jan 2019, 11:15
ARI Moenchhofstrasse 12-14, Seminarraum 1

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