Modelling of spectra and model atmospheres of evolved stars (A talk from the parallel world) Yakiv V.Pavlenko Main astronomical observatory 27 Sabolotnoho, Kyiv, Ukraine

04/02/06 4 VIII Torino Workshop, Granada, Febr.2006 Collaborators Carlos Abia (UG) Carlos Abia (UG) Greg Harries (UCL) Greg Harries (UCL) Yakovina Larisa(MAO) Yakovina Larisa(MAO) Kaminsky Bogdan (MAO) Kaminsky Bogdan (MAO) Hugh Jones (UH) Hugh Jones (UH) Nye Evans(Keele) Nye Evans(Keele) Hilmar Duerbeck(OU) Hilmar Duerbeck(OU) Sveta Zhukovska (MAO) Sveta Zhukovska (MAO) Thomas Geballe Thomas Geballe (UKIRT) (UKIRT)

04/02/06 5 VIII Torino Workshop, Granada, Febr.2006 Stars of interest: Hydrogen-rich stars Hydrogen-rich stars --- M-giants --- C-giants --- V838 Mon Hydrogen poor stars Hydrogen poor stars --- R CrB --- Sakurai’s object

04/02/06 6 VIII Torino Workshop, Granada, Febr.2006 Outline Model atmospheres and fits to SEDs Model atmospheres and fits to SEDs Isotopic ratios ( 12 C/ 13 C) Isotopic ratios ( 12 C/ 13 C) Abundances (Lithium abundances) Abundances (Lithium abundances)

04/02/06 7 VIII Torino Workshop, Granada, Febr.2006 PROCEDURE Model atmospheres Model atmospheres SAM12 (ATLAS12) 1D, Convection + radiation, LTE, No sinks and sources of energy Opacity sampling for line opacity Synthetic spectra Synthetic spectra WITA WITA1D,LTE, Voigt function for lines VCS theory for H lines SEDs

04/02/06 8 VIII Torino Workshop, Granada, Febr.2006 OPACITIES: C/O < 1, C/O < 1, Opacity sources: VO, TiO; H 2 O, CO Methane C/O > 1 C/O > 1 CN, CO, CH, C 2,HCN, C 3, CN, CO, CH, C 2,HCN, C 3, --- [H]?? --- isotopes!

04/02/06 9 VIII Torino Workshop, Granada, Febr.2006 Opacities (missed continuum absorption in the blue, line lists (both atomic and molecular), isotops, Opacities (missed continuum absorption in the blue, line lists (both atomic and molecular), isotops, chemical abundances and equilibrium, chemical abundances and equilibrium, 3-D convection, 3-D convection, sphericity effects, sphericity effects, the dust, the dust, stellar winds. stellar winds. Problems:

04/02/06 10 VIII 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,

04/02/06 11 VIII Torino Workshop, Granada, Febr.2006 C-giants

04/02/06 12 VIII Torino Workshop, Granada, Febr.2006 New grid 1-D model atmosphes Teff= 3400 – 2000 Teff= 3400 – 2000 log g = 1. 0 log g = 1. 0 metallicity -4, -3.5, -3, -2.5, -2, -1.5, -1, -0.5, 0, 1, 1.5, 2 metallicity -4, -3.5, -3, -2.5, -2, -1.5, -1, -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 & NHC New HCN & NHC

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04/02/06 15 VIII Torino Workshop, Granada, Febr.2006 Sakurai's object (V4334 Sgr)

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04/02/06 21 VIII Torino Workshop, Granada, Febr.2006 V838 Mon

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04/02/06 24 VIII 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 25 VIII Torino Workshop, Granada, Febr.2006 The quality of fits to observed spectra depends on: OBSERVED SPECTRA (slopes, de- redenning, resolution) OBSERVED SPECTRA (slopes, de- redenning, resolution) Model atmospheres Model atmospheres Input data for the synthetic spectra Input data for the synthetic spectra

04/02/06 26 VIII Torino Workshop, Granada, Febr.2006 Fine analysis of stellar spectra (Abundance analysis) Input: a) Model atmospheres b) Line lists c) Partition functons, dissociation constants... d) chemical bounds

04/02/06 27 VIII Torino Workshop, Granada, Febr.2006 Lithium in C-stars

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04/02/06 30 VIII Torino Workshop, Granada, Febr.2006 Problems of Li abundance determination in C-giants Line lists (CN, C2,...) Line lists (CN, C2,...) Heavy elements (lists, abundances) Heavy elements (lists, abundances) 3D 3D NLTE NLTE Veiling Veiling

04/02/06 31 VIII Torino Workshop, Granada, Febr.2006 CO bands ( 12C/13C isotopic ratio )

04/02/06 32 VIII Torino Workshop, Granada, Febr C/13C in globular clusters M71: [Fe/H] = -0.7 M71: [Fe/H] = -0.7 M5: [Fe/H] = -1.2 M5: [Fe/H] = -1.2 M13: [Fe/H]= -1.4 M13: [Fe/H]= -1.4 M3: [Fe/H] = -1.6 M3: [Fe/H] = -1.6

04/02/06 33 VIII Torino Workshop, Granada, Febr.2006 Fits to observed spectra

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04/02/06 37 VIII 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,

04/02/06 38 VIII Torino Workshop, Granada, Febr C/13C in Sakurai’s object Main problems to be solved: Main problems to be solved: --- dust veiling --- dust veiling --- Model atmosphere with peculiar abundances --- Model atmosphere with peculiar abundances

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04/02/06 42 VIII Torino Workshop, Granada, Febr.2006 Conclusions Model atmospheres and theoretical spectra must be obtained in the framework of self-consistent approach. Model atmospheres and theoretical spectra must be obtained in the framework of self-consistent approach. Iterative procefure of abundances determination should be implemented. Iterative procefure of abundances determination should be implemented. Different spectral ranges should be used. Different spectral ranges should be used. Input data used in modelling must be improved. Input data used in modelling must be improved.

04/02/06 43 VIII Torino Workshop, Granada, Febr But this is a snare and a delusion, as the more esoteric branches of astrophysics have been built up on the assumption that we understand things like stellar masses, evolution (YP: and abundances:).... Thus if the fundation is shaky, so is superstructure. V.Trimble,R.A.Bell:

to be continued... /