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Unfolding the Milky Way Bulge

This research explores the complex structure and formation history of the Milky Way bulge, using spectroscopic and photometric data. The study investigates the presence of multiple populations, age distributions, and abundance patterns in the bulge region.

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Unfolding the Milky Way Bulge

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  1. Unfolding the Milky Way Bulge Oscar A. Gonzalez PhD student @ ESO-Garching 3rd Subaru conference: Galactic Archaeology, Deep field and the formation of the Milky Way, Japan, 2011

  2. The Milky Way bulge seems to be very complex (or we are just very confused…) StructureX-shape outer regions |b|>5Saito+2011, McWilliam+2010, Nataf+2010 AgesDominated by old populations? Clarkson+2008 (and many others) Significant population of younger stars? Bensby+2011 McWilliam & Zoccali 2010 Bensby et al. 2011

  3. The Milky Way bulge seems to be very complex StructureX-shape outer regions |b|>5Saito+2011, McWilliam+2010, Nataf+2010 AgesDominated by old populations? Clarkson+2008 (and many others) Bensby+2011 Stellar abundances mixed populations? Hill et al. 2011 (also Bensby+2011) Babusiaux et al 2010 (also Soto+2007) Two peaks in the MDF with different kinematics Possible evidence for a classical spheroid + bar

  4. Stellar abundances mixed populations Alpha-element abundances (Ca, Mg, Ti, Si) by spectral synthesis from FLAMES-GIRAFFE spectra of 650 K giants in 4 Bulge fields and a homogeneous comparison with 40 disk giants Gonzalez et al. 2011a Metal-poor Bulge: a-enhanced as the thick disk Metal-rich Bulge: a-poor as the thin disk

  5. Stellar abundances mixed populations Three fields along the minor axis: b = -4, -6 and -12 Metal–poor component shows no variations in a-enhancement Johnson et al. 2011 Gonzalez et al. 2011a

  6. The mapping problem A large coverage is required in order to obtain the global picture of the Bulge 1 full multi-band mapping + 5 year epochs in Ks for variability campaign VISTA variables in the Via Lactea (VVV) public survey

  7. A method for extinction, structure and metallicity maps Build the Luminosity function to study the Ks distribution of red clump giants Difference between the red clump color in BW and any field is a function of reddening Photometric metallicities from CMDs in the absolute plane (J-Ks)0 Interpolation between GC ridge lines with known [Fe/H] Gonzalez et al. 2011b

  8. A method for extinction, structure and metallicity maps Extinction maps for the outer bulge and the very inner regions with up to 3’ resolution Metallicity maps which trace the minor axis gradient observed in HR studies Gonzalez et al. 2011b

  9. A method for extinction, structure and metallicity maps Extinction maps for the outer bulge and the very inner regions with up to 3’ resolution Web tool to obtain extinction values. Link available soon at the VVV survey page

  10. VVV data allows to trace the photometric properties of the RC in order to: • Obtain extinction maps sensitive to small scale variations • Trace the Bulge structure (X-shape, bar, inner structure) • Measure photometric metallicity distributions which resemble spectroscopic measurements • Trace the bulge metallicity gradients. • All this coupled with: • HR and LR in several fields to measure [Fe/H] and [a/Fe] • Comparison to recent bulge formation models Unfold the formation history of the Milky Way Bulge

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