Modelling of spectra and model atmospheres of evolved stars
(A talk from the parallel world)(A talk from the parallel world)
Yakiv V.PavlenkoYakiv V.Pavlenko
Main astronomical observatoryMain astronomical observatory
27 Sabolotnoho, Kyiv, Ukraine 27 Sabolotnoho, Kyiv, Ukraine
www.mao.kiev.ua/staff/ypwww.mao.kiev.ua/staff/yp
04/02/06 4VIII Torino Workshop, Granada,
Febr.2006
CollaboratorsCollaborators
Carlos Abia (UG)Carlos Abia (UG)Greg Harries Greg Harries
(UCL)(UCL)Yakovina Yakovina
Larisa(MAO)Larisa(MAO)Kaminsky Bogdan Kaminsky Bogdan
(MAO)(MAO)Hugh Jones (UH)Hugh Jones (UH)
Nye Nye Evans(Keele)Evans(Keele)
Hilmar Hilmar Duerbeck(OU)Duerbeck(OU)
Sveta Zhukovska Sveta Zhukovska (MAO)(MAO)
Thomas GeballeThomas Geballe
(UKIRT)(UKIRT)
04/02/06 5VIII Torino Workshop, Granada,
Febr.2006
Stars of interest:Stars of interest:Hydrogen-rich starsHydrogen-rich stars--- --- M-giantsM-giants--- C-giants--- C-giants--- V838 Mon--- V838 MonHydrogen poor starsHydrogen poor stars--- --- R CrBR CrB--- Sakurai’s object--- Sakurai’s object
04/02/06 6VIII Torino Workshop, Granada,
Febr.2006
OutlineOutlineModel atmospheres and fits Model atmospheres and fits
to SEDsto SEDsIsotopic ratios (Isotopic ratios (1212C/C/1313C)C)Abundances (Lithium Abundances (Lithium
abundances)abundances)
04/02/06 7VIII Torino Workshop, Granada,
Febr.2006
PROCEDUREPROCEDURE
Model atmospheresModel atmospheres
SAM12 (ATLAS12)SAM12 (ATLAS12)
1D,1D,
Convection + Convection + radiation,radiation,
LTE,LTE,
No sinks and sources No sinks and sources of energyof energy
Opacity sampling forOpacity sampling for
line opacityline opacity
Synthetic spectraSynthetic spectra WITAWITA1D,1D,LTE,LTE,Voigt function for Voigt function for
lineslinesVCS theory for H VCS theory for H
lineslinesSEDsSEDs
04/02/06 8VIII Torino Workshop, Granada,
Febr.2006
OPACITIES:OPACITIES:
C/O < 1,C/O < 1,Opacity Opacity
sources:sources:
VO, TiO;VO, TiO;
HH22O, COO, CO
MethaneMethane
C/O > 1C/O > 1
CN, CO, CN, CO, CH, CH, CC22,HCN, C,HCN, C33,,
--- [H]?? --- [H]??
--- isotopes!--- isotopes!
04/02/06 9VIII Torino Workshop, Granada,
Febr.2006
Opacities (missed continuum Opacities (missed continuum absorption in the blue, line lists absorption in the blue, line lists (both atomic and molecular), (both atomic and molecular), isotops,isotops,
chemical abundances and chemical abundances and equilibrium,equilibrium,
3-D convection,3-D convection, sphericity effects,sphericity effects, the dust,the dust, stellar winds.stellar winds.
Problems:
04/02/06 10VIII Torino Workshop, Granada,
Febr.2006
Astronomy often progresses amoeba-like: the advance in one pseudopod may not move the animal very far, but permits other parts to advance in their turn and can reveal portions of the organism that are in danger of being left behind. V.Trimble, R.A.Bell, Q.Jl.R.astr.Soc.(1981),22, 361-
379
04/02/06 12VIII Torino Workshop, Granada,
Febr.2006
New grid 1-D model New grid 1-D model atmosphesatmosphes
Teff= 3400 – 2000Teff= 3400 – 2000 log g = 1. 0log g = 1. 0 metallicity -4, -3.5, -3, -2.5, -2, -1.5, -metallicity -4, -3.5, -3, -2.5, -2, -1.5, -
1, -0.5, 0, 1, 1.5, 21, -0.5, 0, 1, 1.5, 2 [C/O] = 0.003, 0.007, 0.01, 0.02, 0.03 [C/O] = 0.003, 0.007, 0.01, 0.02, 0.03 New HCN & NHCNew HCN & NHC
04/02/06 15VIII Torino Workshop, Granada,
Febr.2006
Sakurai's object (V4334 Sakurai's object (V4334 Sgr)Sgr)
04/02/06 24VIII Torino Workshop, Granada,
Febr.2006
“...Given the web of interconnected uncertainties and errors presented here, one is initially tempted to give up on stellar atmospheres completely and turn to something simple like cosmology.”
V.Trimble & R.A, Bell:
04/02/06 25VIII Torino Workshop, Granada,
Febr.2006
The quality of fits to The quality of fits to observed spectra depends observed spectra depends
on:on:OBSERVED SPECTRA OBSERVED SPECTRA
(slopes, de-redenning, (slopes, de-redenning, resolution)resolution)
Model atmospheresModel atmospheresInput data for the synthetic Input data for the synthetic
spectraspectra
04/02/06 26VIII Torino Workshop, Granada,
Febr.2006
Fine analysis of stellar spectra(Abundance analysis)
Input:Input:
a) Model atmospheresa) Model atmospheres
b) Line listsb) Line lists
c) Partition functons, dissociation c) Partition functons, dissociation constants...constants...
d) chemical boundsd) chemical bounds
04/02/06 30VIII Torino Workshop, Granada,
Febr.2006
Problems of Li abundance Problems of Li abundance determination in C-giantsdetermination in C-giants
Line lists (CN, C2, ...)Line lists (CN, C2, ...) Heavy elements (lists, abundances)Heavy elements (lists, abundances) 3D3D NLTENLTE VeilingVeiling
04/02/06 31VIII Torino Workshop, Granada,
Febr.2006
CO bandsCO bands((12C/13C isotopic ratio12C/13C isotopic ratio))
04/02/06 32VIII Torino Workshop, Granada,
Febr.2006
12C/13C in globular 12C/13C in globular clustersclusters
M71: [Fe/H] = -0.7M71: [Fe/H] = -0.7 M5: [Fe/H] = -1.2M5: [Fe/H] = -1.2 M13: [Fe/H]= -1.4M13: [Fe/H]= -1.4 M3: [Fe/H] = -1.6M3: [Fe/H] = -1.6
04/02/06 33VIII Torino Workshop, Granada,
Febr.2006
Fits to observed spectraFits to observed spectra
04/02/06 37VIII Torino Workshop, Granada,
Febr.2006
Pavlenko, Yakiv V., Jones, Hugh R. A., Longmore, Andrew J., 2003, 'Carbon abundances and 12C/13C from globular cluster giants.' MNRAS, 345, 311-324.
04/02/06 38VIII Torino Workshop, Granada,
Febr.2006
12C/13C in Sakurai’s 12C/13C in Sakurai’s objectobject
Main problems to be solved: Main problems to be solved: --- dust veiling--- dust veiling --- Model atmosphere with peculiar --- Model atmosphere with peculiar
abundancesabundances
04/02/06 42VIII Torino Workshop, Granada,
Febr.2006
ConclusionsConclusions
Model atmospheres and theoretical Model atmospheres and theoretical spectra must be obtained in the spectra must be obtained in the framework of self-consistent approach.framework of self-consistent approach.
Iterative procefure of abundances Iterative procefure of abundances determination should be implemented.determination should be implemented.
Different spectral ranges should be used.Different spectral ranges should be used. Input data used in modelling must be Input data used in modelling must be
improved.improved.
04/02/06 43VIII Torino Workshop, Granada,
Febr.2006
... But this is a snare and a delusion, as the more esoteric branches of astrophysics have been built up on the assumption that we understandthings like stellar masses, evolution(YP: and abundances:). ... Thus if the fundation is shaky,so is superstructure.
V.Trimble,R.A.Bell: