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Preliminary results for the Gaia-ESO UVES tests

Preliminary results for the Gaia-ESO UVES tests. C. Allende Prieto Instituto de Astrofísica de Canarias. Team members. Expected FTE Giraffe FTE UVES C. Allende Prieto (IAC) 0.1 0.1

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Preliminary results for the Gaia-ESO UVES tests

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  1. Preliminary results for the Gaia-ESO UVES tests C. Allende Prieto Instituto de Astrofísica de Canarias

  2. Team members Expected FTE Giraffe FTE UVES • C. Allende Prieto (IAC) 0.1 0.1 • A. Asensio Ramos (IAC) 0.1 - • F. Garzón (IAC) 0.05 - • J. González-Hernández (IAC) 0.05 (Madrid) • Paul Compére (IAC) 0.5 - • C. González-Fernández (Alicante) 0.05 - • Matthias Steffen (AIP) - 0.3 • Swetlana Hubrig (AIP) - 0.1 • Eric Depagne (AIP) - 0.2 • Michael Weber (AIP) - 0.1 total 0.85 + 0.8 = 1.65

  3. Test (input) data • Gaussian-smoothed (FWHM=0.095 Å) synthetic spectra with noise (S/N=40,70,100) simulating Gaia-ESO UVES observations (4800-6800 Å) of 50 late-type (approx. 4000 < Teff < 6500 K) stars: parameters are Teff,logg,[Fe/H], [/Fe], micro-turbulence • Model atmospheres (MARCS, from website) • Linelist (from VALD)

  4. Preliminary tests • Based on Kurucz model atmospheres (ODFNEW) • Kurucz’s atomic and molecular linelists (upgraded with Barklem et al. Damping constants) • Synthetic spectral computed with iq-package (Koesterke) and our own continuum opacities (Allende Prieto et al. 2003 and subsequent upgrades) • Continuum flattening by chopping the spectrum in pieces and setting their mean to one • Fittings with FERRE (F90 code that uses Nelder-Mead optimization algorithm and quadratic interpolation in fluxes) • Three (Teff,logg,[Fe/H]) and four (Teff,logg,[Fe/H],[/Fe]) parameters considered (micro-turbulence set at 2 km/s) • Initially R=40,000 but then redone at R=60,000

  5. Fittings (Teff,logg,[Fe/H]) S/N=100

  6. Fittings (Teff,logg,[Fe/H],[/Fe] S/N=100

  7. Fittings (Teff,logg,[Fe/H],[/Fe] S/N=100

  8. Fittings (Teff,logg,[Fe/H],[/Fe] S/N=70

  9. Fittings (Teff,logg,[Fe/H],[/Fe] S/N=40

  10. Effect of S/N (70 vs. 100)

  11. Effect of S/N (40 vs. 100)

  12. 3 vs. 4 parameters [Fe/H] Teff logg 1-(robust) 0.06 dex 75 K 0.08 dex

  13. Preliminary conclusions • Model fits are reasonably good, but systematics are apparent (which is useful information) • Same exercise with a consistent linelist, but still Kurucz models, would be useful to discern linelist/models effects • If one assumes a 2=1, the fittings will give S/N= 69 36, 54  23, 36  11 for input S/N=100, 70 and 40 (4 parameters). Metal-poor and warm stars fit better, i.e. the largest discrepancies are found on the metal-rich cool end • S/N doesn’t seem to affect much: random errors due to random noise in the spectra are negligible • Modest effect of considering 4 instead of 3 param. • We are well positioned to repeat the exercise with consistent model fluxes (MARCS+VALD)

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