Bibcode
Li, Y.; Beers, T. C.; Allende Prieto, C.; Wilhelm, R.; Yanny, B.; Newberg, H.
Referencia bibliográfica
American Astronomical Society, 201st AAS Meeting, #16.13; Bulletin of the American Astronomical Society, Vol. 34, p.1126
Fecha de publicación:
12
2002
Número de citas
0
Número de citas referidas
0
Descripción
Discovery of the true nature of the halo of the Galaxy has long been
limited by the number of stars with available spectroscopy and
photometry. This constraint will soon be lifted. While undertaking a
thorough spectroscopic follow-up of ~ 1,000,000 extragalactic sources,
the Sloan Digital Sky Survey (SDSS) will ALSO obtain spectra of as many
as ~ 100,000 Galactic sources (30,000 of which will be available with
DR-1, the first data release from SDSS). With a bright limit of V ~ 14,
the SDSS stellar sample will be, by far, the largest spectroscopic
survey of the Galactic halo and the thick disk yet obtained. The
spectral coverage of SDSS is 3900--9100 Å, with a resolving power
δ λ /λ ~ 2000. These data can potentially provide
radial velocities, temperatures, and gravities, as well as measured
abundances of Fe, Ca, Na, Mg, and C, for stars with spectral types in
the range A to K. The spectra are flux-calibrated, and 5-band photometry
is available for all targets, allowing for reasonably accurate distance
estimates. The limited -- and highly variable -- signal-to-noise ratios
of the spectra, together with the large sample size, require the
development of fast and robust automated methods of analysis. As a first
step, we have calculated a grid of synthetic fluxes based on LTE model
atmospheres and spectral syntheses. We are currently exploring different
algorithms to optimally extract the information in the spectra from the
comparison with the synthetic spectra. Preliminary results exploiting a
genetic algorithm are presented for about 4000 stars in the Early Data
Release.