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DEXstars

DEXstars. C. Allende Prieto Instituto de Astrofísica de Canarias. Stars with DEX. Sample of order 200 000 stars Useful for studies of Galactic structure Chemical evolution Galaxy assembly Pool to discover interesting stars

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DEXstars

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  1. DEXstars C. Allende Prieto Instituto de Astrofísica de Canarias

  2. Stars with DEX • Sample of order 200 000 stars • Useful for studies of Galactic structure • Chemical evolution • Galaxy assembly • Pool to discover interesting stars • Beyond DEX: parallel observing, pointings to known Galactic stellar systems (open/globular clusters, associations, star-forming regions, streams …)

  3. Gaia RAVE SDSS/SEGUE 106 Sample size DEX APOGEE 105 RED: free from subjective Target selection 8 12 18 V magnitude

  4. Census Halo Giants Thin disk F,G-type M-types Thick disk K-type

  5. Potential of DEX stellar spectra • Resolving power lower than usual • Bluer Wavelengths • CH, CaI, CaII,MgI, MgII FeI (lines and cont.) HI (lines and cont.) …

  6. Radial velocity precision Montecarlo simulations

  7. Stellar parameters • Compute a theoretical grid of spectra (4000<Teff<8000 K, -2.5<[Fe/H]<+0.5, 2.0<logg<5.0) • Add (Gaussian) noise and try to recover parameters at S/N=5,10,20,40,80 • Nelder-Mead N-D minimization (grid on RAM) • Continuum correction by a polynomial sigma-clipping algorithm

  8. Examples

  9. Precision on parameters

  10. Summary • Excellent region for stellar work! • A good flux calibration would make a difference • DEXstars pipeline software can follow model for SDSS/SEGUE but differences: more stars/ less frequencies likely to have better (relative) flux calibration and more sensitivity of the continuum in blue to parameters a more direct aproach (N-dim grids, with N~6)

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