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