spectra and model atmospheres of evolved stars (A talk from the parallel world) (A talk from the parallel world) Yakiv V.Pavlenko Yakiv V.Pavlenko Main astronomical Main astronomical observatory observatory 27 Sabolotnoho, Kyiv, 27 Sabolotnoho, Kyiv, Ukraine Ukraine www.mao.kiev.ua/staff/yp www.mao.kiev.ua/staff/yp
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Modelling of spectra and model atmospheres of evolved stars (A talk from the parallel world) Yakiv V.Pavlenko Main astronomical observatory 27 Sabolotnoho,
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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
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,
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
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Febr.2006
C-giantsC-giants
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Febr.2006
New grid 1-D model New grid 1-D model atmosphesatmosphes
“...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:
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Febr.2006
The quality of fits to The quality of fits to observed spectra depends observed spectra depends
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 39VIII Torino Workshop, Granada,
Febr.2006
04/02/06 40VIII Torino Workshop, Granada,
Febr.2006
04/02/06 41VIII Torino Workshop, Granada,
Febr.2006
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.