A Detailed Characterization of the Milky Way Bulge with APOGEE

García Pérez, A. E.; Johnson, Jennifer; Allende-Prieto, C.; Cunha, Katia M. L.; Hearty, Fred; Holtzman, Jon A.; Majewski, Steven R.; Nidever, David L.; Schiavon, Ricardo P.; Sobeck, Jennifer; Zasowski, Gail
Bibliographical reference

American Astronomical Society, AAS Meeting #225, #319.06

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1
2015
Number of authors
11
IAC number of authors
2
Citations
0
Refereed citations
0
Description
An important part of the history of the Milky Way is encoded in the dynamics and chemistry of the inner Galaxy, which contains about 30% of its mass. It is only in the last few years that a composite picture of the bulge has begun to emerge: recent evidence points towards a population made of multiple components. The origin of the bulge appears to be in the disk and the disk-instabilities, although a component associated with mergers (a classical bulge) may also exist. The high-resolution (R=22,500), near-infrared (H-band) SDSS-III/APOGEE-1 survey provides a more complete characterization of the entire bulge as it penetrates the dust and probes down to the Galactic plane. APOGEE-1 collected spectra for approximately 15,000 inner Galaxy stars and derived the associated chemical composition data via an automated spectral analysis based on accurate stellar spectra models. Our statistical analysis of the highly accurate (~0.1 dex) bulge metallicities confirms the presence of multiple bulge components, which change in proportion to each other as a function of height from the plane. There are two metal-rich components that seem to dissipate in our high latitude fields (b ≥ 12o), and the metal-poor components become very weak at low latitude (|b| < 4o). We are analyzing and comparing the individual element abundances for this sample (which includes α and C, among other elements) to that of other Galactic components. This enhances the characterization of the bulge and permits a thorough exploration of the origin and formation of its component populations (e.g., a classical bulge or a thick disk component).