Oscar A. Gonzalez

PhD student @ ESO-Garching

3rd Subaru conference: Galactic Archaeology, Deep field and the formation of the Milky Way, Japan, 2011

The Milky Way bulge seems to be very complex The Milky Way bulge seems to be very complex (or we are just very confused…)(or we are just very confused…)

Structure X-shape outer regions |b|>5 Saito+2011, McWilliam+2010, Nataf+2010

Ages Dominated by old populations? Clarkson+2008 (and many others) Significant population of younger stars? Bensby+2011

Bensby et al. 2011Bensby et al. 2011McWilliam & Zoccali 2010McWilliam & Zoccali 2010

Hill et al. 2011Hill et al. 2011(also Bensby+2011)(also Bensby+2011)

Babusiaux et al 2010Babusiaux et al 2010 (also Soto+2007)(also Soto+2007)

Structure X-shape outer regions |b|>5 Saito+2011, McWilliam+2010, Nataf+2010

Ages Dominated by old populations? Clarkson+2008 (and many others) Bensby+2011

Stellar abundances mixed populations?

Two peaks in the MDF with different kinematics

Possible evidence for a classical spheroid + bar

The Milky Way bulge seems to be very complexThe Milky Way bulge seems to be very complex

Stellar abundances mixed populationsStellar 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

Metal-poor Bulge:

-enhanced as the thick disk

Metal-rich Bulge:

-poor as the thin disk

Gonzalez et al. 2011aGonzalez et al. 2011a

Three fields along the minor axis: b = -4, -6 and -12

Metal–poor component shows no variations in -enhancement

Stellar abundances mixed populationsStellar abundances mixed populations

Gonzalez et al. 2011aGonzalez et al. 2011a Johnson et al. 2011Johnson et al. 2011

A large coverage is required in order to obtain the global picture of the Bulge

The mapping problemThe mapping problem

VISTA variables in the Via Lactea (VVV) public surveyVISTA variables in the Via Lactea (VVV) public survey

1 full multi-band mapping + 5 year epochs in Ks for variability campaign

A method for extinction, structure and metallicity mapsA method for extinction, structure and metallicity maps

Difference between the red clump color in BW and any field is a function of reddening

Build the Luminosity function to study the Ks distribution of red clump giants

Photometric metallicities from CMDs in the absolute plane

(J-Ks)0 Interpolation between GC ridge lines with known [Fe/H]

Gonzalez et al. 2011bGonzalez et al. 2011b

A method for extinction, structure and metallicity mapsA 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. 2011bGonzalez et al. 2011b

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

A method for extinction, structure and metallicity mapsA method for extinction, structure and metallicity maps

VVV data allows to trace the photometric properties of the VVV data allows to trace the photometric properties of the RC in order to: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 [/Fe]Comparison to recent bulge formation models

Unfold the formation history of the Milky Way Bulge