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Atmospheres: Empirical or Theoretical ?

Atmospheres: Empirical or Theoretical ?. (some selected) Observed Spectral Libraries GUNN, J.E.; STRYKER, L.L. 1983 ( 3130 to 10800 Å ) JACOBY, G.H., HUNTER, D.A., CHRISTIAN, C.A. , 1984 ( 3130 to 7000 Å at 4 Å ) PICKLES, A. J. , 1998 ( 1150-25000 Å at 5 Å )

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Atmospheres: Empirical or Theoretical ?

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  1. Atmospheres:Empirical or Theoretical ? (some selected) Observed Spectral Libraries GUNN, J.E.; STRYKER, L.L. 1983 (3130 to 10800 Å) JACOBY, G.H., HUNTER, D.A., CHRISTIAN, C.A., 1984 (3130 to 7000Å at 4Å ) PICKLES, A. J. , 1998 (1150-25000Å at 5 Å ) PRUGNIEL, P., SOUBIRA, C., 2002 (ELODIE 4100-6800 Å) VALDES ET AL., 2004 (INDO-US 3460-9464 at 4Å) LE BORGNE ET AL. 2003 (STELIB 3200 to 9500Å at 3Å) SANCHEZ-BLAZQUEZ ET AL. 2006 (MILES 3525-7500Åat 2.3 Å)

  2. M10 M4 SANCHEZ-BLAZQUEZ ET AL. 2006

  3. Theoretical: ATLAS code Robert L. Kurucz http://kurucz.harvard.edu/ Buser, R. AIU, Basel, Switz. Cuisinier, F. Dpt. Astr. Rio de Janeiro, Brasil Lejeune, T. OA Univ. Coimbra, Portugal Castelli, F. INAF OATS Bonifacio, P. INAF OATS Bertone, E. INAOE, Pue, Mex Chavez, M. INAOE, Pue, Mex Rodriguez , L. INAOE, Pue, Mex

  4. Theoretical: NextGen Hauschildt, Allard & Baronhttp://www.hs.uni-hamburg.de/EN/For/ThA/phoenix/index.html • 1D plane parallel or spherical symmetric radiative transfer • multilevel NLTE calculations for atoms with a total of more than 10000 levels and 100000 primary lines • line blanketing and background opacities are included by design • over 650 species in the EOS including atoms, ions, molecules and grains • depth dependent Voigt profiles for Stark and van der Waals broadening • dynamical opacity sampling (dOS) of about 42 Million atomic lines and over 550 Million (and growing) molecular lines (more than 10GB worth of data) • spectra can be calculated for any desired resolution (standard are 20000 to 500000 wavelength points spread from the UV to the radio)

  5. Solar Model From Hauschildt et al

  6. Teff vs. gravitymodel distribution Log T(eff) vs. log g model distribution Luminosity class: MK V = small solid dots MK IV = big solid dots MK III = small open dots MK II--I = big open dots Evolutionary tracks M = 1, 2, 5, 10 Mo (from Girardi et al. 00) Bertone et al 05

  7. HD 154760, G2V (Gunn & Stryker 83) best fit ATLAS model (Bertone, E et al. 04)

  8. Accuracy of Teffs, gATLAS vs. NextGen • Star BD+38 2457: standard deviation of flux residuals for fitting models; dotted line for log g = 0, dash-dotted log g(NG) = 5.5 log g(ATLAS) = 5.0 • T(eff) = 4850 ±70 K, log g = 5.5 ± 0.5 dex s(min) = 0.12NextGen • T(eff) =4520 ± 30 K, log g = 4.0 ± 0.5 dex s(min) = 0.06ATLAS Bertone et al 05

  9. Gunn & Stryker (1983) Jacoby et al. (1984) smindistribution vs. spectral type • ATLAS • NextGen Bertone et al 05

  10. Gunn & Stryker (1983) Jacoby et al. (1984) Teff scale Teff scale Bertone et al 05

  11. Bolometric corrections Empirical calibrations: • Flower (1977) dotted line for MS stars dashed for giants • Johnson (1966) solid) • Bessell (1991) dashed-dotted) • Code et al. (1976) crosses

  12. M Giant Stars Models by Fluks et al (1994) • Database of M giants (97 MIII stars spectra from 3800-9000 A) • Pletz et al. Atmospheric models • match with optical spectra used to determine Teff • In general poor U-B-V fluxes • e.g. strange B-V or V-K colours • Combine observed (3800-9000) with synthetic best match models to obtain a wide wavelength coverage • Apply scale corrections to reproduce observed average colour-colour relations

  13. Gustafsson B., Edvardsson B., Eriksson K., Jørgensen U.G., Nordlund Å, Plez B., 06 B. Gustafsson, R. A. Bell, K. Eriksson, and A. Nordlund, 75 Photospheric surface fluxes from 1300Å to 20μm sampled with λ/Δλ = 20,000 Theoretical: MARCS stellar model-atmosphere and flux library http://marcs.astro.uu.se/ This is a grid of one-dimensional, plane-parallel andspherical LTE model atmospheres and sampled fluxes. The library supplies model-atmosphere tables and sampled energy fluxes for about 9000 stellar models with Teff between 4000 and 8000K (step 250K) Log g between -1.0 to 5.0 (step 0.5) Metallicities between -5.0 and 1.0 Plane-parallel models are calculated for log g from +3.0 to +5.0 Models with spherical geometry are supplied for log g < +4.0, masses of 0.5, 1.0, 2.0 and 5.0 MSun,

  14. M-Giant Scales

  15. Bessel Castelli Plez, 98

  16. Observed vs Theretical Colours

  17. My own method: from Fluks et al. 1994

  18. M Giant Spectra

  19. Other Theoretical Libraries A High-Resolution Stellar Library for Evolutionary Population Synthesis. Martins, González Delgado, Leitherer, Cerviño, Hauschildt 2005 http://www.iaa.csic.es/~rosa/research/synthesis/HRES/ESPS-HRES.html 2500-10500 Ang Library of Synthetic Spectra Munari, Sordo, Castelli, Zwitter, 2006 http://web.pd.astro.it/adsd/index.html

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