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3D and NLTE analysis for large stellar surveys Karin Lind Uppsala University, Sweden Martin Asplund, Paul Barklem, Andrey Belyaev, Maria Bergemann, Remo.

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Presentation on theme: "3D and NLTE analysis for large stellar surveys Karin Lind Uppsala University, Sweden Martin Asplund, Paul Barklem, Andrey Belyaev, Maria Bergemann, Remo."— Presentation transcript:

1 3D and NLTE analysis for large stellar surveys Karin Lind Uppsala University, Sweden Martin Asplund, Paul Barklem, Andrey Belyaev, Maria Bergemann, Remo Collet, Zazralt Magic, Anna Marino, Jorge Meléndez, Yeisson Osorio

2 Outline -Introduction - 1D LTE/NLTE -Worst-case scenarios -Recent progress -Calibration techniques -Practical implementation -Applications - 3D LTE/NLTE -Worst-case scenarios -Observational tests -Mg : 1D/ /LTE/NLTE -Ca : 1D/ /3D/LTE/NLTE -Applications

3 Motivation Galactic archaeology by chemical tagging of FGK stars - Statistics : Soon > 10 6 stars - Precision (S/N, wavelength range) : σ [X/H] < 0.1dex, σ Teff <150K, σ log(g) <0.3dex - Accuracy (assumptions: 1D, LTE, atomic data) : σ [X/H] < 0.5 dex, σ Teff <400K, σ log(g) < 1 dex

4 Methods Model atmosphere Detailed rad. Transfer 1D/ /3D LTE 1D/3D LTE/NLTE R. Collet

5 NLTE line formation

6 (1D) Is it really necessary? Is it safe? N-

7 Worst-case scenario I NaD lines in metal-poor horisontal branch stars Lind et al. 2011, Marino et al B-I

8 Worst-case scenario II OI 777nm triplet at very low metallicities Fabbian et al LTE trend

9 Input data for NLTE analysis Energy levels + oscillator strengths + photo-ionization cross sections Red boxes : have sufficient(?) data Blue boxes : missing e.g. QM photo-ionisation, but NLTE still attempted

10 Input data for NLTE analysis Blue boxes : QM hydrogen collisions exist or will exist

11 Input data for NLTE analysis Solar neighborhood MDF Halo MDF [X/Fe] vs [Fe/H] Most important free parameter in NLTE modelling of Fe is FeI+HI collisional cross-section Black – LTE Blue – NLTE with no hydrogen collisions

12 Calibration techniques: ionisation balance Korn et al FeI/FeII ionisation equilibrium calibrated using Hipparcos gravities  S(H)=3

13 Calibration techniques: excitation balance Bergemann & Gehren 2008 “Thus, NLTE can solve the discrepancy between the abundances derived from the MnI resonance triplet at 403 nm and excited lines, which is found in analyses of metal-poor subdwarfs and subgiants”  S(H)=0.05

14 Calibration techniques: CLV Allende Prieto et al. (2004) Solar centre-to-limb variation of OI lines

15 Practical implementation I “Curves-of- growth” from UV-NIR: 3200 FeI lines 107 FeII lines ΔNLTE T eff =6500K log(g)=4.0 ξ=2km/s Lind et al. (2012)

16 Practical implementation II Pre-computed departure coefficients  NLTE synthesis T. Nordlander

17 FeI NLTE grid Lind et al. (2012)

18 Application : metal-poor stars Ruchti et al. (2012) LTE NLTE +PHOT

19 Application : metal-poor stars LTENLTE+PHOT Serenelli et al. (2013)

20 3D (LTE/NLTE) Is it really necessary? Is it safe?

21 Stagger grid Magic et al. 2014

22 Abundance patterns 3D N- LTE Keller et al. (2014) Dashed –200 M sun PISN Solid – 60M sun fallback

23 Worst-case scenario III Li isotopic abundances Asplund et al. 2006Lind et al D N- LTE 3D N- LTE

24 Observational tests: the Sun Pereira et al “We confronted the models with observational diagnostics of the [solar] temperature profile: continuum centre-to-limb variations (CLVs), absolute continuum fluxes, and the wings of hydrogen lines. We also tested the 3D models for the intensity distribution of the granulation and spectral line shapes. ” “We conclude that the 3D hydrodynamical model is superior to any of the tested 1D models.”

25 Observational tests: low [Fe/H] Klevas et al FeI line assymmetries in the metal-poor giant HD122563

26 1.5/3D + NLTE LiI : Asplund et al. 2003, Sbordone et al OI, FeI : Shchukina et al OI : Pereira et al. 2010, Prakapavičius et al LiI, NaI, CaI : Lind et al. 2013

27 Ways forward

28 Mg b in a VMP SG 1D LTE 1D NLTE LTE NLTE HD Teff=5780K log(g)=3.7 [Fe/H]=-2.4 “No” free parameters! Yeisson Osorio

29 Ca in a VMP dwarf LTE NLTE 1D 3D HD19445 Teff=6000K log(g)=4.5 [Fe/H]=-2.0

30 Ca in a VMP dwarf LTE NLTE 1D 3D HD19445 Teff=6000K log(g)=4.5 [Fe/H]=-2.0

31 Start ? Goal Bullets: Optical CaI lines Squares: NIR CaII triplet Ca in a EMP TO G64-12 Teff=6430K log(g)=4.0 [Fe/H]=-3.0

32 Start ? Goal Bullets: Optical CaI lines Squares: NIR CaII triplet Ca in a EMP TO

33 Start ? Goal Bullets: Optical CaI lines Squares: NIR CaII triplet Ca in a EMP TO

34 Start ? Goal Bullets: Optical CaI lines Squares: NIR CaII triplet Ca in a EMP TO

35 Start ? Goal Bullets: Optical CaI lines Squares: NIR CaII triplet Ca in a EMP TO

36 Ways forward A : NLTE-sensitive, B : not NLTE-sensitive


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