Bibcode
Wilson, John C.; Simmonsand, Audrey; Skrutskie, Michael F.; Schultheis, Mathias; Schneider, Donald P.; Robin, Annie C.; Pan, Kaike; Oravetz, Daniel; O'Connell, Robert W.; Meszaros, Sz.; Malanushenko, Viktor; Malanushenko, Elena; Hearty, Fred R.; Girardi, Léo; Frinchaboy, Peter M.; Eisenstein, Daniel J.; Ebelke, Garrett; Bizyaev, Dmitry; Beers, Timothy C.; Allende-Prieto, C.; Zasowski, Gail; Nidever, David; Holtzman, Jon; Schiavon, Ricardo P.; Smith, Verne V.; Johnson, Jennifer A.; Majewski, Steven R.; Shetrone, Matthew; Cunha, Katia; García Pérez, Ana E.
Bibliographical reference
The Astrophysical Journal Letters, Volume 767, Issue 1, article id. L9, 7 id. (2013).
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4
2013
Citations
56
Refereed citations
52
Description
Despite its importance for understanding the nature of early stellar
generations and for constraining Galactic bulge formation models, at
present little is known about the metal-poor stellar content of the
central Milky Way. This is a consequence of the great distances involved
and intervening dust obscuration, which challenge optical studies.
However, the Apache Point Observatory Galactic Evolution Experiment
(APOGEE), a wide-area, multifiber, high-resolution spectroscopic survey
within Sloan Digital Sky Survey III, is exploring the chemistry of all
Galactic stellar populations at infrared wavelengths, with particular
emphasis on the disk and the bulge. An automated spectral analysis of
data on 2403 giant stars in 12 fields in the bulge obtained during
APOGEE commissioning yielded five stars with low metallicity ([Fe/H]
<= –1.7), including two that are very metal-poor [Fe/H] ~
–2.1 by bulge standards. Luminosity-based distance estimates place
the 5 stars within the outer bulge, where 1246 of the other analyzed
stars may reside. A manual reanalysis of the spectra verifies the low
metallicities, and finds these stars to be enhanced in the
α-elements O, Mg, and Si without significant α-pattern
differences with other local halo or metal-weak thick-disk stars of
similar metallicity, or even with other more metal-rich bulge stars.
While neither the kinematics nor chemistry of these stars can yet
definitively determine which, if any, are truly bulge members, rather
than denizens of other populations co-located with the bulge, the newly
identified stars reveal that the chemistry of metal-poor stars in the
central Galaxy resembles that of metal-weak thick-disk stars at similar
metallicity.
Related projects
Chemical Abundances in Stars
Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to
Carlos
Allende Prieto