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Sara Lucatello

INAF-Osservatorio Astronomico di Padova Dipartimento di Astronomia, Università di Padova. Sara Lucatello. Extremely metal poor CH stars: a window on the first generation of intermediate mass stars. Team. Timothy Beers - Michigan State University

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Sara Lucatello

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  1. INAF-Osservatorio Astronomico di Padova Dipartimento di Astronomia, Università di Padova Sara Lucatello Extremely metal poor CH stars: a window on the first generation of intermediate mass stars

  2. Team Timothy Beers - Michigan State University Eugenio Carretta - Osservatorio Astronomico di Padova Norbert Chriestlieb – Hamburger Sternewarte Judith Cohen – California Institute of Technology Raffaele Gratton - Osservatorio Astronomico di Padova Jennifer Johnson – DAO Solange Ramirez - California Institute of Technology

  3. Metal poor CH stars Surveys of metal-deficient stars find a large number of stars with strong CH bands Explanation analogous to classical CH stars Three kinds of CH stars? I Normal n-capture elements II r-process elementsrich III s-process elements rich

  4. What can we learn from CEMP? Constraints on the IMF Constraints on nucleosynthesis at low Z

  5. Constraints on the IMF Surveys find ~30% CEMP at [Fe/H]<-2.5 dex ~50% of CH stars s-process binaries ~30% IMS • IMF works for Ba and classical CH stars! Binary fraction ~60% Almost flat IMF at low Z? CNO and ¹²C/¹³C

  6. Nucleosynthesis Early galactic chemical evolution s and r-process at low Z

  7. Broadened lines Measuring C and N abundance [C/Fe]=2.6±0.1dex [N/Fe]=2.1±0.1dex

  8. Radial velocity curve Hires & Uves data Palomar Data Orbital Parameters P=(3.413±0.001)d To(MJD)=(52066.921±0.006)d G=(-178.7±0.5) km/s K=(52.0±0.6) km/s e=0 asini=(2.442±0.029)10e6 km f(m)=(0.0498±0.002) Msun

  9. Rotational velocity vsini=(9.7±1.5) km/s measured from our spectra From orbital parameters + few assumptions expected synchrone velocity: Vsinisyn=<(13.5±3.9)km/s Compatible!!

  10. What do we infer from this information? P<<Pch~100d Common envelope phase Circular orbit Synchrone orbit

  11. s and r process elements [Ba/Fe]=1.4±0.2 [Eu/Fe]<1.1 dex If Ba r-process: [Eu/Fe]=2.2 [Pb/Fe]=3.3±0.2 dex

  12. Abundances summary Teff=6625Klog(g)=4.3 [Fe/H]=-2.7 vt=1.4 km/s

  13. Is theory able to explain these values? A preliminary model Gallino et al. (private communication) Model for [Fe/H]=-2.6 M=1.5Msun Mass of the evolved companion Dilution factor 10 Standard pocket M(¹³C)=4 10e-6 Msun at top of He intershell

  14. Updated Existing sample 10 stars Vr variables Vr constant No info on Vr

  15. Conclusions This object is clearly a case of s-process rich, binary star: enrichment through mass transfer from an AGB companion Sample too limited to draw conclusions Abundance analysis and radial velocity infos are both crucial

  16. Work in progress Vrad monitoring Abundance analysis 2-4 spectra for ~30 objects 7 UVES spectra 5 Keck spectra 4 TNG spectra

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