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Model atmospheres of the peculiar C-giants

Model atmospheres of the peculiar C-giants. Yakiv Pavlenko : yp@mao.kiev.ua http://www.mao.kiev.ua/staff/yp Larisa Yakovina : yakovina@mao.kiev.ua MAO NASU, http://www.mao.kiev.ua. Acknowledgements. Robert L. Kurucz (Harvard) Greg J.Harris (UCL) Jonathan Tennyson (UCL)

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Model atmospheres of the peculiar C-giants

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  1. Model atmospheres of the peculiar C-giants Yakiv Pavlenko: yp@mao.kiev.ua http://www.mao.kiev.ua/staff/yp Larisa Yakovina: yakovina@mao.kiev.ua MAO NASU, http://www.mao.kiev.ua

  2. Acknowledgements • Robert L. Kurucz (Harvard) • Greg J.Harris (UCL) • Jonathan Tennyson (UCL) • Aleksandr Pugach (MAO )

  3. Outlines • Peculiar C-giants • Opacities in C-star atmospheres • R CrB type C-star DY Per • Our set of model atmospheres

  4. Model atmospheres on the net: ftp://ftp.mao.kiev.ua/pub/users/yp/Cmod/cmod.pdf ftp://ftp.mao.kiev.ua/pub/users/yp/Cmod/hdef.htm ftp://ftp.mao.kiev.ua/pub/users/yp/Cmod/hsol.htm ftp://ftp.mao.kiev.ua/pub/users/yp/Cmod/cmod.ppt

  5. Opacities in SAM12 (C/O > 1) • Opacity grid from ATLAS12 • C I, N I, O I bound free transitions from Pavlenko & Zhukovskaya (2003) • Lines of diatomic molecules from Kurucz’s CD-ROM 15, 18 • HCN (Harris et al 2003, 2006) • CIA (Borisow et al. 1997) • Atomic lines from VALD (Kupka et al. 1999)

  6. Model atmospheres • Total 182 model atmospheres: • 2800 <= Teff <= 3200 • Log g=0, 32 models of log g= -1, -0.5, 0.5, 1 • -3.5 <= [Fe/H] <= 0 • 1/9 <= H/He <=9/1 • 0.06 <= log(C/O) <= 2.7 • 0 <= [N/Fe] <= 2.7

  7. Temperature structure of some model atmospheres of different Tef, log g, H/He, [Fe/H], C/O, [N/Fe]

  8. Effects of Tef in the synthetic spectra (Tef= 2800, 3000 K)

  9. Effects of surface gravity in the synthetic spectra (log g=0, +1)

  10. Effects of hydrogen deficiency in the synthetic spectra (H/He=9/1 (Sun), 5/5)

  11. Effects of metallicity in the synthetic spectra ([Fe/H]=0, -1)

  12. Effects of carbon and nitrogen abundances in the synthetic spectra (C/O=0.5, 1; [N/Fe]=0, 0.3, 1)

  13. Fit of calculated SED to the observed SED of DY Per (Yakovina et al. 2008, Astr. Rept., accepted.)

  14. Conclusions • Our model atmospheres of C-giants computed in the framework of the classical assumptions are not ideal, but the models are suitable for qualitative and quantitative analysis of the observed spectra. • Moreover, we obtain a god fit of our theoretical spectra to the observed SEDs of DY Per. • Our models can be used at least for: -- evaluation purposes; -- as a starting point for the future, i.e. more sophisticated, model atmosphere computations.

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