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Dr. Alan Alves-Brito ARC Super Science Fellow

Red giant stars as tracers of the chemical evolution of the Galactic bulge. Dr. Alan Alves-Brito ARC Super Science Fellow. Main Collaborators. Dr. Jorge Mel éndez ( IAG/USP, Brazil ) Prof. Martin Asplund ( RSAA, Australia ) Dr. Thomas Bensby ( Lund Observatory, Sweden ). DIRBE@COBE

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Dr. Alan Alves-Brito ARC Super Science Fellow

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

  2. 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 18-20.

  3. DIRBE@COBE Dwek et al. 1995 OPTICAL IMAGE Axel Mallenhoff 2001 Scientific Motivation • age • kinematics • dynamics • chemical enrichment Astounding Stories of Super Science - Hobart, April 18-20.

  4. 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 18-20.

  5. When and how the Galactic bulge was formed? stellar content (classical) vs.morphology(pseudobulge)Kormendy & Kennicutti 2004see also Elmegreen et al. 2008 Credit:University of Texas, MacDonald Observatory Astounding Stories of Super Science - Hobart, April 18-20.

  6. Main goal: Galactic genealogy Grevesse & Sauval 1998 Big Bang Solar Abundance Pattern Fe-peak Neutron capture Light elements Astounding Stories of Super Science - Hobart, April 18-20.

  7. Chemical enrichment: [X/Fe] ~ SF [O/Fe] ---> SNII/SNIa Tinsley 1979; Chiappini 2004 Astounding Stories of Super Science - Hobart, April 18-20.

  8. Lecureur et al. 2007 and previous works FLAMES:UVES@VLT: R = 20,000 - 40,000 Bulge(giants) vs. Disks (dwarves) [Fe/H] = log(Fe/H)_star - log(Fe/H)_sun 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. Astounding Stories of Super Science - Hobart, April 18-20.

  9. 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 18-20.

  10. High resolution spectra [Fe/H] = log(Fe/H)_star - log(Fe/H)_sun -1.5 < [Fe/H] < +0.5 PHOENIX@GeminiMIKE@MagellanUVES@VLTELODIE@OHP2dcoude@McDonaldHIRES@KeckR = / ≥ 60,000 Astounding Stories of Super Science - Hobart, April 18-20.

  11. Methods Astounding Stories of Super Science - Hobart, April 18-20.

  12. Alves-Brito, Meléndez, Asplund et al. 2010, A&A, 513, 35 Meléndez, Asplund, Alves-Brito et al. 2008 : 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 18-20.

  13. Bensby, Alves-Brito, Oye et al. 2010, A&A Bensby, Alves-Brito, Oye et al. 2011, ApJ (outer disk) Optical data: MIKE@Magellan R = 55,000 : S/N = 100 Inner Disk (44 giants : 3-7 kpc) The metal poor bulge and the (inner) thick disk are indistinguishable  inner disk ,local thick and thin disks; * bulge Astounding Stories of Super Science - Hobart, April 18-20.

  14. 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 18-20.

  15. Optical data: FLAMES@VLT R = 30,000 : S/N = 100 474 giants in 4 different fields 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 Astounding Stories of Super Science - Hobart, April 18-20.

  16. Bulge vs. local and inner thick-disk: Conclusions • Similar chemical evolution: genetic link • Short timescale, similar SFR and IMF • Classical bulge vs. secular/dynamical Astounding Stories of Super Science - Hobart, April 18-20.

  17. Perspectives • 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 2011-2020): ~1 billion of stars to V=20. 3D map of our Galaxy • Australian GMT, HERMES • SIMPLE@E-Extremely Large Telescopes: high R of dwarf stars in the bulge! More info: bulge vs. inner disksAge spread, kinematics and chemical abundances can constrain different models of bulge formation Astounding Stories of Super Science - Hobart, April 18-20.

  18. Thank you very much Astounding Stories of Super Science - Hobart, April 18-20.

  19. Bulge MDF Astounding Stories of Super Science - Hobart, April 18-20.

  20. t = GC +- 2.5 Gyr (Ortolani et al. 1995; Zoccali et al. 2003) CMD @HST t = 10Gyr ([Fe/H] = 0) Unevolved MS t = 10Gyr ([Fe/H] =0.5) ~245,000 stars l,b = 10.25,-20.65 Sahu et al. 2006 Astounding Stories of Super Science - Hobart, April 18-20.

  21. Meléndez, Asplund, Alves-Brito et al. 2008, A&A : IR: Phoenix@Gemini-S [O/Fe] vs. [Fe/H] # 19 gigantes do bojo + 49 gigantes de comparação bulge thick disk thin disk halo [O/Fe] = 0.41 - 0.02*[Fe/H] [O/Fe] = 0.39 - 0.01*[Fe/H] [O/Fe] = 0.03  0.09 dex The bulge and the (local) thick disk are indistinguishable [(C+N)/Fe] = cte [(C+N)/Fe] vs. [Fe/H] Astounding Stories of Super Science - Hobart, April 18-20.

  22. Ryde, Gustafson, Edvardson et al. 2009, A&A IR: CRIRES@VLT : CNO, R = 70,000 : S/N = 40-110 # 11 giants in the bulge X Meléndez et al. 2008 [O/Fe] @ IR : Phoenix and CRIRES results are consistent Astounding Stories of Super Science - Hobart, April 18-20.

  23. Thick disk formationMichelle et al. 2011 • Accretion • Heating via a minor merger • Intense SF in a gas turbulent environment • Radial migration Astounding Stories of Super Science - Hobart, April 18-20.

  24. Ages of Disk Stars Thick disk: ~10 Gyr Thin disk: <8 Gyr Bensby et al. (2007) Astounding Stories of Super Science - Hobart, April 18-20.

  25. Inner disk stars Astounding Stories of Super Science - Hobart, April 18-20.

  26. Inner disk: Toomre Diagram Bensby et al. (2010) Astounding Stories of Super Science - Hobart, April 18-20.

  27. 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 18-20.

  28. Uncertainties • Continuum level • Line fitting (?) • Damping parameters • Stellar atmospheres : 1D models • Non-LTE effects Astounding Stories of Super Science - Hobart, April 18-20.

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