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Development of New Stellar Spectra Libraries and Abundance Analysis Techniques

The IAC C. Allende-Prieto summary outlines significant software developments, including new template libraries for the reduction pipeline and ongoing research by PhD student Emma Fernández Alvar on deriving abundances of Ca, Mg, C, and Si. A notable project involves building a library of stellar spectra from SDSS data, primarily focused on various stellar types using Kurucz and MARCS models. This aims to improve the accuracy of abundance measurements and continuum normalization while enabling more precise analysis of stellar populations.

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Development of New Stellar Spectra Libraries and Abundance Analysis Techniques

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  1. SEGUE Activity at the IAC C. Allende Prieto

  2. Summary • Software developments: new template libraries and software for the reduction pipeline. NOT (yet) for the SSPP. • Research on deriving abundances of Ca, Mg, C and Si (Emma Fernández Alvar - PhD student) • Building a library of stellar spectra from SDSS (pre-BOSS) stellar spectra (Victor de la Reina - summer student)

  3. New libraries • M-K type 3500-5000 K (Kurucz) • G-F type 4750-6500 K (Kurucz) • F-A-type 6250-8750 K (Kurucz) • A-type 8500-11500 K (Kurucz) • B-type 12000-26000 K (Kurucz) • O-type 27000-39000 K (Kurucz) • Hot DA white dwarfs (I. Hubeny) • Cool DA white dwarfs (D. Koester) • NLTE B-type and O-type (Tlusty) • M-L type 2000-3500 K (MARCS) • L-T type 800-2500 K (Sudarsky et al.)

  4. New libraries • M-K type 3500-5000 K (Kurucz) • G-F type 4750-6500 K (Kurucz) • F-A-type 6250-8750 K (Kurucz) • A-type 8500-11500 K (Kurucz) • B-type 12000-26000 K (Kurucz) • O-type 27000-39000 K (Kurucz) • Hot DA white dwarfs (I. Hubeny) • Cool DA white dwarfs (D. Koester) • NLTE B-type and O-type (Tlusty) • M-L type 2000-3500 K (MARCS) • L-T type 800-2500 K (Sudarsky et al.) READY!

  5. New libraries • M-K type 3500-5000 K (Kurucz) • G-F type 4750-6500 K (Kurucz) • F-A-type 6250-8750 K (Kurucz) • A-type 8500-11500 K (Kurucz) • B-type 12000-26000 K (Kurucz) • O-type 27000-39000 K (Kurucz) • Hot DA white dwarfs (I. Hubeny) • Cool DA white dwarfs (D. Koester) • NLTE B-type and O-type (Tlusty) • M-L type 2000-3500 K (MARCS) • L-T type 800-2500 K (Sudarsky et al.) Including [/Fe]

  6. Software • Gaussian LSF (fiber, ) • Quadratic interpolation of fluxes • Normalization by blocks • Full covariance matrix • Successful tests performed on MILES library

  7. Software • Gaussian LSF (fiber, ) • Quadratic interpolation of fluxes • Normalization by blocks • Successful tests performed on MILES library

  8. Continuum on This Work MILES parameters (Cenarro et al. 2009) [Fe/H] Teff logg Distributions of residuals

  9. Continuum off This Work MILES parameters (Cenarro et al. 2009) [Fe/H] Teff logg Distributions of residuals

  10. Actual SDSS/SEGUE data • NGC 2420: plate 2078 mjd 53378 • Reddening ignored! • No continuum flattening • <Fe/H> = -0.8 +/- 0.2 dex for G- and F-type stars in plate

  11. Actual SDSS data

  12. NGC 2420 • The [Fe/H] offset disappears when we flatten the continuum • The metallicities for the cluster stars show less scatter, comparable with k24 and ngs

  13. NGC 2420

  14. Abundances of Ca, Mg, C, Si • PhD student Emma Fernández Alvar • Derived sensitivity of spectrum to changes in the abundances of some 20 elements as function of Teff,logg,[Fe/H] • Currently performing simulations with Gaussian noise to quantify better previous results. Next: to incorportate Connie Rockosi’s noise model

  15. An empirical spectral library • Summer student Víctor de la Reina • Based on SSPP ‘adop’ parameters • Product is not a data base, but software • Now 3 parameters, later maybe 4 • Problem split into two: 1) choosing boxes, 2) averaging spectra • Filtering by spectra and at pixel level • 0.03 dex in logTeff, 0.5 dex in logg, 0.5 dex in [Fe/H] gives ~ 800 classes (median population ~ 100 stars/box) for 300,000+ spectra in survey=segue1-2

  16. Summary • Software developments: new template libraries and software for the reduction pipeline. NOT (yet) for the SSPP. • Research on deriving abundances of Ca, Mg, C and Si (Emma Fernández Alvar - PhD thesis) • Building a library of stellar spectra from SDSS (pre-BOSS) stellar spectra (Victor de la Reina - summer student)

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