atmospheres: empirical or theoretical ?
DESCRIPTION
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 ) - PowerPoint PPT PresentationTRANSCRIPT
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 (1150-25000 Å 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 3525-7500Å at 2.3 Å )
SANCHEZ-BLAZQUEZ ET AL. 2006
M10
M4
Theoretical: ATLAS code
http://kurucz.harvard.edu/Robert L. Kurucz
Castelli, F. INAF OATSBonifacio, P. INAF OATS
Bertone, E. INAOE, Pue, MexChavez, M. INAOE, Pue, MexRodriguez , L. INAOE, Pue, Mex
Buser, R. AIU, Basel, Switz.Cuisinier, F. Dpt. Astr. Rio de Janeiro, BrasilLejeune, T. OA Univ. Coimbra, Portugal
Theoretical: NextGen Hauschildt, Allard & Baron
http://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)
Solar Model
From Hauschildt et al
Teff vs. gravity model 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
HD 154760, G2V (Gunn & Stryker 83)
best fit ATLAS model (Bertone, E et al. 04)
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) = 0.12 NextGen • T(eff) = 4520 ± 30 K, log g = 4.0 ± 0.5 dex s(min) = 0.06 ATLAS
Bertone et al 05
smin
distribution vs.
spectral type
Gunn & Stryker (1983)
Jacoby et al. (1984)
o ATLAS
• NextGen
Bertone et al 05
Teff scaleTeff scale Gunn & Stryker (1983)
Jacoby et al. (1984)
Bertone et al 05
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
M Giant Stars
• 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
Models by Fluks et al (1994)
Theoretical: MARCS stellar model-atmosphere and flux library
This is a grid of one-dimensional, plane-parallel and spherical 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,
http://marcs.astro.uu.se/
Gustafsson B., Edvardsson B., Eriksson K., Jørgensen U.G., Nordlund Å, Plez B., 06B. Gustafsson, R. A. Bell, K. Eriksson, and A. Nordlund, 75
Photospheric surface fluxes from 1300Å to 20μm sampled with λ/Δλ = 20,000
M-Giant Scales
0.00
2.00
4.00
6.00
8.00
10.00
12.00
0 2 4 6 8 10
MK Type
V-K
Fluks
Perrin
3.35
3.4
3.45
3.5
3.55
3.6
3.65
0 2 4 6 8 10
MK Type
Log
(Tef
f)
Fluks
Perrin
Fluks et al 94 Perrin et al 98 RidgwayV-K Teff V-K Teff
M0 3.80 3895 3.78 3895 3895M1 4.10 3810 4.02 3810 3810M2 4.38 3736 4.30 3730 3730M3 4.65 3666 4.64 3640 3640M4 5.02 3574 5.10 3560 3560M5 5.84 3434 5.96 3420 3420M6 6.86 3309 6.94 3243 3250M7 8.16 3126 8.13 3087M8 9.16 2890 9.74 2806M9 9.82 2667
M10 10.23 2500
23002700310035003900
Teff
V-K
Fluks
Perrin
Bessel
Bessel
BesselCastelliPlez, 98
Observed vs
Theretical Colours
My own method: from Fluks et al. 1994
M Giant Spectra
http://www.iaa.csic.es/~rosa/research/synthesis/HRES/ESPS-HRES.html
A High-Resolution Stellar Library for Evolutionary Population Synthesis.
Other Theoretical Libraries
2500-10500 Ang Library of Synthetic SpectraMunari, Sordo, Castelli, Zwitter, 2006
Martins, González Delgado, Leitherer, Cerviño, Hauschildt 2005
http://web.pd.astro.it/adsd/index.html