Dr. Alan Alves-Brito ARC Super Science Fellow Red giant stars as tracers of the chemical evolution of the Galactic bulge

Astounding Stories of Super Science - Hobart, April Main Collaborators  Dr. Jorge Meléndez (IAG/USP, Brazil)  Prof. Martin Asplund (RSAA, Australia)  Dr. Thomas Bensby (Lund Observatory, Sweden)

Astounding Stories of Super Science - Hobart, April Scientific Motivation  age  kinematics  dynamics  chemical enrichment Dwek et al OPTICAL IMAGE Axel Mallenhoff 2001

Astounding Stories of Super Science - Hobart, April Tracers of the Galactic bulge K and M giant stars in the field (e.g. Mcwillian & Rich 1994; Fulbright et al. 2006,2007; Zoccali et al. 2006; Lecureur et al. 2007; Zoccali et al. 2008; Meléndez et al. 2008; Ryde et al. 2009; Alves-Brito et al. 2010; Bensby et al. 2010; Alves-Brito et al. 2012b, in preparation) Giant stars in globular clusters (e.g. Alves-Brito et al. 2006; Barbuy et al. 2006; Barbuy et al. 2009) Dwarf, sub-giant and giant stars in gravitational microlenses (e.g. Cohen et al. 2008;2009; Bensby et al. 2008;2009; Alves-Brito et al. 2012c, in preparation)

Astounding Stories of Super Science - Hobart, April When and how the Galactic bulge was formed? Credit: University of Texas, MacDonald Observatory stellar content (classical) vs. morphology (pseudobulge) Kormendy & Kennicutti 2004 see also Elmegreen et al. 2008

Astounding Stories of Super Science - Hobart, April Main goal: Galactic genealogy Big Bang Fe-peak Light elements Neutron capture Grevesse & Sauval 1998 Solar Abundance Pattern

Astounding Stories of Super Science - Hobart, April Chemical enrichment: [X/Fe] ~ SF [O/Fe] ---> SNII/SNIa Tinsley 1979; Chiappini 2004

Astounding Stories of Super Science - Hobart, April Bulge (giants) vs. Disks (dwarves) The bulge chemical enrichment is dominated by SNII (massive stars). It must have formed faster than both the thick and thin disks Ballero et al. (2007): MDF and [Mg/Fe] imply different IMFs for the bulge and the thick disk. Lecureur et al and previous works R = 20, ,000 [Fe/H] = log(Fe/H)_star - log(Fe/H)_sun

Astounding Stories of Super Science - Hobart, April Concerns   Giants (bulge) vs. dwarves (disks): Teff  Zero points on stellar parameters  Line list (different lines, atomic data)  Solar abundances  Methods of analysis

Astounding Stories of Super Science - Hobart, April High resolution spectra R = /  ≥ 60,000 [Fe/H] = log(Fe/H)_star - log(Fe/H)_sun -1.5 < [Fe/H] < +0.5

Astounding Stories of Super Science - Hobart, April Methods

Astounding Stories of Super Science - Hobart, April Alves-Brito, Meléndez, Asplund et al. 2010, A&A, 513, 35 Meléndez, Asplund, Alves-Brito et al : CNO Optical data: R = 60,000 : S/N = 200 thick  thin same knee (thick disk) The bulge and the (local) thick disk are indistinguishable

Astounding Stories of Super Science - Hobart, April Bensby, Alves-Brito, Oye et al. 2010, A&A Bensby, Alves-Brito, Oye et al. 2011, ApJ (outer disk) Optical data: R = 55,000 : S/N = 100 Inner Disk (44 giants : 3-7 kpc)  inner disk,  local thick and thin disks; * bulge The metal poor bulge and the (inner) thick disk are indistinguishable

Astounding Stories of Super Science - Hobart, April Alves-Brito, Johnson, Bensby et al. 2012, in preparation The bulge (normal giants and microlensed ones) and the thick disk are indistinguishable

Astounding Stories of Super Science - Hobart, April Gonzalez, Rejkuba, Zoccali et al. 2011, A&A; also using Alves-Brito et al. 2010’s data Different techniques and independent methods ¡confirm our results! The bulge and the thick disk are indistinguishable Optical data: R = 30,000 : S/N = giants in 4 different fields

Astounding Stories of Super Science - Hobart, April  Similar chemical evolution: genetic link  Short timescale, similar SFR and IMF  Classical bulge vs. secular/dynamical Bulge vs. local and inner thick-disk: Conclusions

Astounding Stories of Super Science - Hobart, April  What about the heavy elements?  Bulge vs Thin/Thick disk in the Galactic center  The critical -0.3 < [Fe/H] < +0.0 range  Gaia mission (from ): ~1 billion of stars to V=20. 3D map of our Galaxy  Australian GMT, HERMES  Large Telescopes: high R of dwarf stars in the bulge! More info: bulge vs. inner disks Age spread, kinematics and chemical abundances can constrain different models of bulge formation Perspectives

Astounding Stories of Super Science - Hobart, April Thank you very much

Astounding Stories of Super Science - Hobart, April Bulge MDF

Astounding Stories of Super Science - Hobart, April ~245,000 stars l,b = , t = 10Gyr ([Fe/H] = 0) Unevolved MS t = 10Gyr ([Fe/H] =0.5) t = GC Gyr (Ortolani et al. 1995; Zoccali et al. 2003) Sahu et al. 2006

Astounding Stories of Super Science - Hobart, April # 19 gigantes do bojo + 49 gigantes de comparação Meléndez, Asplund, Alves-Brito et al. 2008, A&A : IR: bulge thick disk thin disk halo [O/Fe] vs. [Fe/H] [(C+N)/Fe] vs. [Fe/H] [(C+N)/Fe] = cte [O/Fe] = *[Fe/H] [O/Fe] = *[Fe/H]  [O/Fe] = 0.03  0.09 dex The bulge and the (local) thick disk are indistinguishable

Astounding Stories of Super Science - Hobart, April # 11 giants in the bulge X Meléndez et al Ryde, Gustafson, Edvardson et al. 2009, A&A IR: : CNO, R = 70,000 : S/N = IR : Phoenix and CRIRES results are consistent

Astounding Stories of Super Science - Hobart, April Thick disk formation Michelle et al  Accretion  Heating via a minor merger  Intense SF in a gas turbulent environment  Radial migration

Astounding Stories of Super Science - Hobart, April Ages of Disk Stars Thick disk: ~10 Gyr Thin disk: <8 Gyr Bensby et al. (2007)

Astounding Stories of Super Science - Hobart, April Inner disk stars

Astounding Stories of Super Science - Hobart, April Inner disk: Toomre Diagram Bensby et al. (2010)

Astounding Stories of Super Science - Hobart, April Uncertainties ∆T = ±100K : ∆logg = ±0.30 dex : ∆v = ±0.20 Km/s Fe: 0.03 dex Mg: 0.07 dex C: 0.11 dex Si: 0.12 dex N: 0.11 dex Ca: 0.10 dex O: 0.14 dex Ti: 0.17 dex

Astounding Stories of Super Science - Hobart, April Uncertainties  Continuum level  Line fitting (?)  Damping parameters  Stellar atmospheres : 1D models  Non-LTE effects