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Non-LTE modeling of narrow emission components of He and Ca lines in optical spectra of classical T Tauri stars

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Abstract

Using LTE calculations of the structure of T Tauri stellar atmospheres heated by radiation from an accretion shock (Dodin and Lamzin 2012), we have calculated the spectrum of the hot spot emerging on the stellar surface by taking into account non-LTE effects for He I, He II, Ca I, and Ca II. Assuming the pre-shock gas density N 0 and velocity V 0 to be the same at all points of the accretion stream cross section, we have calculated the spectrum of the star+circular spot system at various N 0, V 0, and parameters characterizing the star and the spot. Using nine stars as an example, we show that the theoretical optical spectra reproduce well the observed veiling of photospheric absorption lines as well as the profiles and intensities of the so-called narrow components of He II and Ca I emission lines with an appropriate choice of parameters. The accreted gas density in all of the investigated stars except DK Tau has been found to be N 0 > 1012 cm−3. We have managed to choose the parameters for eight stars at a calcium abundance in the accreted gas ξ Ca equal to the solar one, but we have been able to achieve agreement between the calculations and observations for TW Hya only by assuming ξ Ca to be approximately a factor of 3 lower than the solar one. The estimated parameters do not depend on interstellar extinction, because they have been determined from the spectra normalized to the continuum level. The calculated intensity of Ca II lines has turned out to be lower than the observed one, but this contradiction can be eliminated by assuming that, in addition to the accreted gas with a high density N 0, a more rarefied gas also falls onto the star. The theoretical equivalent widths and relative intensities of the subordinate He I lines disagree significantly with the observations. This is apparently because non-LTE effects should be taken into account when calculating the structure of the upper layers of the hot spot, the accuracy of the cross sections for collisional processes from upper levels is insufficient, and the spot inhomogeneity should probably be taken into account.

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References

  1. C. C. Batalha, N. M. Stout-Batalha, G. Basri, and M. A. O. Nerra, Astrophys. J. Suppl. Ser. 103, 211 (1996).

    Article  ADS  Google Scholar 

  2. V. B. Berestetskii, E. M. Lifshits, and L. P. Pitaevskii, Course of Theoretical Physics, Vol. 4: Quantum Electrodynamics (Pergamon, Oxford, 1982; Nauka, Moscow, 1989).

    Google Scholar 

  3. J. Bouvier and C. Bertout, Astron. Astrophys. 211, 99 (1989).

    ADS  Google Scholar 

  4. K. Butler and J. Giddings, Newsletter on the Analysis of Astronomical Spectra, No. 9 (Univ. of London, 1985).

    Google Scholar 

  5. N. Calvet and E. Gullbring, Astrophys. J. 509, 802 (1998).

    Article  ADS  Google Scholar 

  6. R. E. H. Clark, J. Abdallah, Jr., and J. B. Mann, Astrophys. J. 381, 597 (1991).

    Article  ADS  Google Scholar 

  7. K. P. Dere, E. Landi, H. E. Mason, et al., Astron. Astrophys. Suppl. Ser. 125, 149 (1997).

    Article  ADS  Google Scholar 

  8. M. S. Dimitrijevic and S. Sahal-Brechot, J. Quant. Spectrosc. Radiat. Transfer 31, 301 (1984).

    Article  ADS  Google Scholar 

  9. A. V. Dodin, S. A. Lamzin, and G. A. Chuntonov, Astron. Lett. 38, 167 (2012).

    Article  ADS  Google Scholar 

  10. A. V. Dodin and S. A. Lamzin, Astron. Lett. 38, 649 (2012).

    Article  ADS  Google Scholar 

  11. J.-F. Donati, M. M. Jardine, S. G. Gregory, et al., Mon. Not. R. Astron. Soc. 386, 1234 (2008).

    Article  ADS  Google Scholar 

  12. J.-F. Donati, S. G. Gregory, S. H. P. Alencar, et al., Mon. Not. R. Astron. Soc. 417, 472 (2011).

    Article  ADS  Google Scholar 

  13. G. J. Ferland, K. T. Korista, D. A. Verner, et al., Publ. Astron. Soc. Pacif. 110, 761 (1998).

    Article  ADS  Google Scholar 

  14. G. F. Gahm, F. M. Walter, H. C. Stempels, et al., Astron. Astrophys. 482, L35 (2008).

    Article  ADS  Google Scholar 

  15. J. F. Gameiro, D. F.M. Folha, and P. P. Petrov, Astron. Astrophys. 445, 323 (2006).

    Article  ADS  Google Scholar 

  16. V. V. Golovatyj, A. Sapar, T. Feklistova, and A. F. Kholtygin, Astron. Astrophys. Trans. 12, 85 (1997).

    Article  ADS  Google Scholar 

  17. Ch. Gräfe, S. Wolf, V. Roccatagliata, et al., Astron. Astrophys. 533, 89 (2011).

    Article  ADS  Google Scholar 

  18. E. Gullbring, L. Hartmann, C. Briceño, and N. Calvet, Astrophys. J. 492, 323 (1998).

    Article  ADS  Google Scholar 

  19. L. Hartmann and J. R. Staufer, Astron. J. 97, 873 (1989).

    Article  ADS  Google Scholar 

  20. C. M. Johns-Krull and J. A. Valenti, Astrophys. J. 561, 1060 (2001).

    Article  ADS  Google Scholar 

  21. A. H. Joy, Astrophys. J. 110, 424 (1949).

    Article  ADS  Google Scholar 

  22. J. H. Kastner, D. P. Huenemoerder, N. S. Schulz, and C. R. Canizares, Astrophys. J. 567, 434 (2002).

    Article  ADS  Google Scholar 

  23. S. J. Kenyon and L. Hartmann, Astrophys. J. Suppl. Ser. 101, 117 (1995).

    Article  ADS  Google Scholar 

  24. A. Königl,, Astrophys. J. 370, L339 (1991).

    Google Scholar 

  25. R. Kurosawa and M.M. Romanova, Mon. Not.R. Astron. Soc. 426, 2901 (2012).

    Article  ADS  Google Scholar 

  26. R. Kurucz, ATLAS9 Stellar Atmosphere Programs and 2 km/s Grid, Kurucz CD-ROMNo. 13 (Smithsonian Astrophys. Observ., Cambridge, MA, 1993).

    Google Scholar 

  27. S. A. Lamzin, Astron. Astrophys. 295, L20 (1995).

    ADS  Google Scholar 

  28. S. A. Lamzin, Astron. Rep. 42, 322 (1998).

    ADS  Google Scholar 

  29. E. Landi, G. Del Zanna, P. R. Young, et al. Astrophys. J. Suppl. Ser. 162, 261 (2006).

    Article  ADS  Google Scholar 

  30. L. Mashonkina, A. J. Korn, and N. Przybilla, Astron. Astrophys. 461, 261 (2007).

    Article  ADS  Google Scholar 

  31. D. Mihalas, Stellar Atmospheres (Freeman, San Francisco, 1978; Mir, Moscow, 1982).

    Google Scholar 

  32. S. N. Nahar, New Astron. 15, 417 (2010).

    Article  ADS  Google Scholar 

  33. P. P. Petrov, G. F. Gahm, J. F. Gameiro, et al., Astron. Astrophys. 369, 993 (2001).

    Article  ADS  Google Scholar 

  34. P. P. Petrov, G. F. Gahm, H. C. Stempels, et al., Astron. Astrophys. 535, 6 (2011).

    Article  ADS  Google Scholar 

  35. H. van Regemorter, Astrophys. J. 136, 906 (1962)

    Article  ADS  Google Scholar 

  36. M. M. Romanova, G. V. Ustyugova, A. V. Koldoba, and R. V. E. Lovelace, Astrophys. J. 610, 920 (2004).

    Article  ADS  Google Scholar 

  37. N. A. Sakhibullin, Modeling Methods in Astrophysics (FEN, Kazan’, 1997) [in Russian].

    Google Scholar 

  38. L. Sbordone, P. Bonifacio, F. Castelli, and R. L. Kurucz, Mem. Soc. Astron. It. Suppl. 5, 93 (2004).

    Google Scholar 

  39. R. P. Schiavon, C. Batalha, and B. Barbuy, Astron. Astrophys. 301, 840 (1995).

    ADS  Google Scholar 

  40. J. H. M. M. Schmitt, J. Robrade, J.-U. Ness, et al., Astron. Astrophys. 432, L35 (2005).

    Article  ADS  Google Scholar 

  41. T. Schöning and K. Butler,, Astron. Astrophys. Suppl. Ser. 78, 551 (1989).

    ADS  Google Scholar 

  42. M. D. Smith, Astron. Astrophys. 287, 523 (1994).

    ADS  Google Scholar 

  43. H. C. Stempels and N. Piskunov, Astron. Astrophys. 408, 693 (2003).

    Article  ADS  Google Scholar 

  44. L. A. Vainshtein, I. I. Sobelman, and E. A. Yukov, Excitation of Atoms and Broadening of Spectral Lines (Nauka, Moscow, 1979; Springer, New York, 2002).

    Google Scholar 

  45. G. V. Zaitseva, A. G. Shcherbakov, and N. A. Stepanova, Sov. Astron. Lett. 16, 350 (1990).

    ADS  Google Scholar 

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Authors and Affiliations

  1. Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow, 119992, Russia

    A. V. Dodin, S. A. Lamzin & T. M. Sitnova

  2. Faculty of Physics, Moscow State University, Moscow, Russia

    A. V. Dodin, S. A. Lamzin & T. M. Sitnova

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  1. A. V. Dodin
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  2. S. A. Lamzin
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  3. T. M. Sitnova
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Correspondence to A. V. Dodin.

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Original Russian Text © A.V. Dodin, S.A. Lamzin, T.M. Sitnova, 2013, published in Pis’ma v Astronomicheskiĭ Zhurnal, 2013, Vol. 39, No. 5, pp. 353–375.

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Dodin, A.V., Lamzin, S.A. & Sitnova, T.M. Non-LTE modeling of narrow emission components of He and Ca lines in optical spectra of classical T Tauri stars. Astron. Lett. 39, 315–335 (2013). https://doi.org/10.1134/S1063773713050010

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