| |
 |
| Paper: |
Making Good Use of Bad Weather: Finding Extremely Metal-Poor Stars in the Clouds |
| Volume: |
458, Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way |
| Page: |
77 |
| Authors: |
Placco, V.; Beers, T. C.; Rossi, S.; Kennedy, C.; Christlieb, N.; Lee, Y. S.; Sivarani, T. |
| Abstract: |
Current results are presented for a new survey effort to search for
Extremely Metal-Poor (EMP) and Carbon Enhanced Metal-Poor (CEMP) stars from
the Hamburg / ESO objective-prism survey (HES). These stars are important
probes of Galactic Chemical Evolution, as they require specific scenarios
and conditions for their formation. Recent results infer that their
distribution among the various structural components of the Milky Way can
also help describe the dynamical process(es) that led to the assembly of
our Galaxy.
We have developed a new method to search for metal-poor stars, based on
identifying stars with apparently strong molecular CH G-band strengths for
their colors. The hypothesis we exploit is that large over-abundances of
carbon are common among metal-poor stars, as has been found by numerous
studies over the past two decades. Estimates of the stellar atmospheric
parameters, as well as carbon abundances, are now available for about 250
of the first candidates, based on follow-up medium-resolution spectra
obtained with bad weather GMOS proposals on the Gemini 8m telescopes, and
also with the Goodman HTS on the SOAR 4.1m telescope. We have over 5000
candidates, they are reasonably bright (10<B<16), and they cover most
of the southern sky. Thus, they are perfect to switch to when weather or
seeing prevents the execution of other programs. There are 13 newly
discovered stars with [Fe/H]<–3.0 in our sample, including four with
[Fe/H]<–3.5 and one with [Fe/H]∼–4.0. This work is important to
provide reliable targets suitable for high-resolution spectroscopy on 8m
class telescopes such as Subaru, to determine the detailed abundance patterns
of these objects. |
|
|
|
|
|
