Galac%c Unprecedented Precision (0.01 dex)

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1 Li Be B Si O Fe Dy Ce Ru Y Pb C a Ti L V b Y Eu Al N Pr d Sr Mo Ba P Ca K Cr S N Sm Gd U Ag Pd Mg Ni Galac%c Unprecedented Precision (0.01 Dep. Astronomia, Univ. São Paulo

2 - Is the observed star-to-star abundance scaver just due to errors in the analyses? - Can we find evidences of real cosmic scaver? What are the causes? - Analyses based on small samples (>=2) #SolarTwins #Binaries #OpenClusters #GlobularClusters #MetalPoorStars

3 Thick disk Star-to-star scatter due to errors or true cosmic scatter? Thin disk 714 stars Bensby et al. 2014

4 Chemical homogeneity in open clusters: 0.03 dex Bovy 2016 Ness et al. 2017

5 Reaching a 0.01 dex precision using stellar twins (T eff ±100K) Very high S/N (> 400) High spectral resolu%on (R > ) Careful selec%on of lines Strictly differen-al approach using stars similar between them ( stellar twins ): - precise rela-ve efec-ve temperartures - line-by-line cancel errors in gf-values - weak dependence on model atmospheres

6 Differen%al abundances A X (element X) log (W/λ) = cte + A X + log (g f ) + log λ - θ χ exc - log k cont,λ Precise differential EW measurements are key to precise differential abundances Bedell, Meléndez, Bean et al. 2014

7 Solar Twins: Defined Solar type stars late F, G, early K Solar analogs about G2V and factor of 2 in chemical composi%on Solar twins very rare stars with similar T eff (within 100 K), gravity & composi%on (0.1 dex) to the Sun's values Implies: [Fe/H] = 0.0±0.1, mass = 1.00±0.05 M & ages = 0 10 Gyr

8 Experiment on precision abundances using solar twins - Magellan 6.5m Telescope & Mike spectrometer - R = 65,000 - S/N = 450 per pixel - coverage nm - Solar spectrum: Vesta - 3 nights of observa%ons Observa-ons of the solar twin 18 Sco BLUE frame RED frame

9 Example of Magellan spectra of 11 solar twins and the Sun (total spectral coverage 3350 A -1µm) Small part ( nm) of solar twin & Sun s spectra Meléndez, Asplund, Gustafsson, Yong 2009

10 [Cr/Fe] distribu%on in 11 solar twins Star-to-star scaver of only dex

11 Δ abundance: Sun - <twins> vs. atomic number Z Sun typical: Δ = 0 Sun weird: Δ 0 Our solar system is not host by a typical Sun Meléndez et al. 200 Meléndez, Asplund, Gustafsson, Yong 2009

12 Sun s anomalies are strongly correlated to the dust condensa%on temperature of the elements! Correla%on is highly significant. Probability ~10-9 to happen by chance Volatile elements ~ 0.08 dex ~ 20% Dust condensation temperature (K) Meléndez, Asplund, Gustafsson, Yong 2009

13 Meléndez et al The missing refractories were used to form dust, planetesimals & terrestrial planets The late accreted gas in the convec%on zone was deficient in refractories

14 Planet effects in binary system with twins 16 Cyg: widely separated pair of solar analogs 16 Cyg A : no planets 16 Cyg B : giant planet (~ 2 M J )

15 Signatures of giant planet forma%on: 16 Cyg binary 16 Cyg A: no planet B: hosts a giant planet

16 Another binary system: XO-2 Both components host planets 0.6 M J >0.3 M J + > 1.4 M J Ramírez et al See also Teske et al. 2015; Biazzo et al. 2015

17 Binary pair ζ Ret with debris disk in one component (ζ 2 ) Saffe et al. (2016) Trend with T cond confirmed by Adibekyan et al. 2016

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19 Teske et al. 2016

20 Chemical inhomogeneity in open clusters: solar twins in M67 Liu et al. 2016

21 Solar twins in M67 are chemically inhomogeneous Two solar twins in M67 differ in ~0.05±0.01 dex Liu et al. 2016

22 Galac%c chemical evolufon: precise stellar ages can be obtained using solar twins We can study [X/Fe] vs. age rather than only [X/Fe] vs. [Fe/H]

23 Solar twin HIP σ (LTE) = dex σ (NLTE) = dex

24 Differen%al method is also useful to obtain high precision stellar parameters (Δ Teff 10 K, Δ log g 0.02 dex) à good stellar masses and ages

25 Diverse abundance signatures unveiled in the solar twin 18 Sco a solar twin younger than the Sun and rich in refractories, s-process and r-process elements Using UV spectra obtained at the VLT / ESO

26 18 Sco (brightest solar twin, V = 5.5) UVES+VLT R = (red) R = (blue) Rich in silver and other n-capture elements Rich in refractory elements Age = 2.9 Gyr Meléndez et al. 2014, ApJ 791, 14 August 10, 2014

27 18 Sco (brightest solar twin, V = 5.5) UVES+VLT R = S/N = 800 Subtrac%ng T cond trend Sr observations Ru Mo Y Zr Pd Ag Ba Eu Sm Nd La Ce Pr Gd Dy Yb AGB model (Amanda Karakas) Meléndez et al. 2014, ApJ

28 Perfect agreement between residual abundances and predic%ons from the SS r-process frac%ons Meléndez et al. 2014, ApJ

29 Abundance ra%os as a func%on of age

30 Spina et al. 2016

31 Spina et al. (2016): chemical clocks

32 Tucci-Maia et al [Y/Mg] can also tell us about mass transfer in binaries

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34 Schirbel et al. 2015

35 Schirbel et al Dust from AGB star?

36 Schirbel et al Signatures of former AGB star

37 Peculiar solar twin Condensa%on temperature of the elements Meléndez et al. 2017, in prep. Why the scaver is so high?

38 Enhanced odd-even effect detected in a solar twin using precise (0.01 dex) abundances, likely due to a peculiar supernova Solar twin - Sun C O Mg Na Al Si S Z Ca Sc Ti V Cr Fe Ni Mn Co Cu Zn Meléndez et al. 2017, in prep. <odd - even> ~ dex

39 Cosmic scaver in metal-poor stars? Cayrel et al True scaver (0.15 dex)?

40 High precision in very metal-poor stars requires high S/N G 64-12, G64-37: Extremely metal-poor twins 6463 K, 6570 K; log g = 4.26, 4.40, [Fe/H] = -3.2, -3.0 Keck, R ~ , S/N ~ 700

41 Distinct abundances in twins G64-12 & G64-37 EMP stars [Fe/H] < -3 Reggiani et al. 2016

42 High Precision in Metal-Poor Stars SAGA, T eff = 6250±250K, log g = 4.0±0.5 dex UVES@VLT R ~ S/N ~ 200 Abundance error = 0.06 dex Star-to-scatter = 0.06 dex Reggiani et al. 2017, to be submived

43 High Precision in Metal-Poor Stars R ~ S/N ~ 200 Abundance error = 0.05 dex Star-to-scatter = 0.05 dex Reggiani et al. 2017, to be submived

44 High precision in metal-rich halo stars

45 R ~ S/N ~ Nissen & Schuster 2010

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47 Field stars born in a globular cluster

48 Differen%al techniques applied to cool metalpoor giants in cluster NGC 6752 ([Fe/H] = -1.6) Yong, D., Meléndez, J., Grundahl, F., et al. 2013

49 Differen%al techniques applied to cool metalpoor giants in NGC 6752 [Fe/H] = -1.6 At high precision ( dex) all elements show abundance variafons Yong, D., Meléndez, J., Grundahl, F., et al. 2013

50 Conclusions - Precision Spectroscopy of solar (& stellar) twins is a powerful tool for Galac%c archaeology - A precision of about 0.01 dex may be needed to disentangle effects of planets and nucleosynthe%c signatures of SN + AGB stars