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A new scheme of radiation transfer in HII regions including transient heating of grains

  • S. K. Ghosh
  • R. P. Verma
Article
  • 29 Downloads

Abstract

A new scheme of radiation transfer for understanding the infrared spectra of HII regions, has been developed. This scheme considers non-equilibrium processes (e.g. transient heating of the very small grains, VSG; and the polycyclic aromatic hydrocarbon, PAH) also, in addition to the equilibrium thermal emission from normal dust grains (BG). The spherically symmetric interstellar dust cloud is segmented into a large number of “onion skin” shells in order to implement the non-equilibrium processes. The scheme attempts to fit the observed SED originating from the dust component, by exploring the following parameters: (i) geometrical details of the dust cloud, (ii) PAH size and abundance, (iii) composition of normal grains (BG), (iv) radial distribution of all dust (BG, VSG & PAH).

The scheme has been applied to a set of five compact H II regions (IRAS 18116 − 1646, 18162 − 2048, 19442 + 2427, 22308 + 5812, and 18434 - 0242) whose spectra are available with adequate spectral resolution. The best fit models and inferences about the parameters for these sources are presented.

Key words

HII regions radiative transfer PAH VSG 

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References

  1. Acker, A., Marcout, J., Ochsenbein, F., Stenholrn, B., Tylenda, R. 1992,Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Munchen, ESO).Google Scholar
  2. Allamandola, L. J., Tielens, A. G. G. M., Barker, J. R. 1985,Astrophys. J. (Lett),290, L25.CrossRefADSGoogle Scholar
  3. Allamandola, L. J., Tielens, A. G. G. M., Barker, J. R. 1989,Astrophys. J. (Suppl.),71, 733.CrossRefADSGoogle Scholar
  4. Barsony, M. 1989,Astrophys. J.,345, 268.CrossRefADSGoogle Scholar
  5. Boulanger, F., Baud, B., van Albada, G. D. 1985,Astr. Astrophys.,144, L9.ADSGoogle Scholar
  6. Chini, R., Krugel, E., Kreysa, E. 1986,Astr: Astrophys.,167, 315.ADSGoogle Scholar
  7. Churchwell, E., Wolfire, M. G., Wood, D. O. S. 1990,Astrophys. J.,354, 247.CrossRefADSGoogle Scholar
  8. de Muizon, M. J., d’Hendecourt, L. B., Geballe, T. R. 1990,Astr. Astrophys.,227, 526.ADSGoogle Scholar
  9. Dent, W. R. F. 1988,Astrophys. J.,325, 252.CrossRefADSGoogle Scholar
  10. Desert, F. X., Boulanger, F., Puget, J. L. 1990,Astr. Astrophys.,237, 215.ADSGoogle Scholar
  11. Desert, F. X., Boulanger, F., Shore, S. N. 1986,Asti: Astrophys.,160, 295.ADSGoogle Scholar
  12. Draine, B. T., Lee, H. M. 1984,Astrophys. J.,285, 89.CrossRefADSGoogle Scholar
  13. Egan, M. P., Leung, C. M., Spagna, G. F. 1988,Computer Physics Communications,48, 271.CrossRefADSGoogle Scholar
  14. Ghosh, S. K., Drapatz, S., Peppel, U. C. 1986,Astr, Astrophys.,167, 341.ADSGoogle Scholar
  15. Ghosh, S. K., Tandon, S. N. 1985,Mon. Not. R. Astr Soc.,215, 315.ADSGoogle Scholar
  16. Jenness, T., Scott, P. F., Padman, R. 1995,Mon. Not. R. Astr. Soc.,276, 1024.ADSGoogle Scholar
  17. Karnik, A. D., Ghosh, S. K. 1999,J. Astrophys. Astr.,20, 23.CrossRefADSGoogle Scholar
  18. Krugel, E., Siebenmorgen, R. 1994,Astr. Astrophys.,282, 407.ADSGoogle Scholar
  19. Laor, A., Draine, B.T. 1993,Astrophys. J.,402, 441.CrossRefADSGoogle Scholar
  20. Leger, A., d’Hendecourt, L. 1987,PAH and Astrophysics (eds.) A. Leger, L. d’Hendecourt & N. Boccara, p 223.Google Scholar
  21. Leger, A., Puget, J. L. 1984,Astr. Astrophys.,137, L5.ADSGoogle Scholar
  22. Leung, C. M. 1975,Astrophys. J.,199, 340.CrossRefADSGoogle Scholar
  23. Leung, C. M. 1976,Astrophys. J.,209, 75.CrossRefADSGoogle Scholar
  24. Lis, D. C., Leung, C. M. 1991,Icarus,91, 7.CrossRefADSGoogle Scholar
  25. Mathis, J. S., Mezger, P. G., Panagia, N. 1983,Astr. Astrophys.,128, 212.ADSGoogle Scholar
  26. Mathis, J. S., Rumpl, W., Nordsieck, K. H. 1977,Astrophys. J.,217, 425.CrossRefADSGoogle Scholar
  27. McCutcheon, W. H., Sato, T., Purton, C. R., Matthews, H. E., Dewdney, P. E. 1995,Astr. J.,110, 1762.CrossRefADSGoogle Scholar
  28. Metcalfe, L., Steel, S. J., Barr, P.,et al. 1996,Astr. Astrophys.,315, L105.ADSGoogle Scholar
  29. Mookerjea, B., Ghosh, S. K. 1999,Bull. Astr Soc. India,27, 567.ADSGoogle Scholar
  30. Moorwood, A. F. M., Lutz, D., Oliva, E.,et al. 1996,Astr. Astrophys.,315, L109.ADSGoogle Scholar
  31. Olnon E M., Raimond, E. (IRAS Science Team) 1986,Astr: Astrophys. (Suppl.),65, 607.ADSGoogle Scholar
  32. Puche, D., Zijistra, A. A., Boettcher, C.,et al. 1988,Astr Astrophys.,206, 89.ADSGoogle Scholar
  33. Puget, J. L., Leger, A. 1989,Annu. Rev. Astron. Astrophys.,27, 161.CrossRefADSGoogle Scholar
  34. Puget, J. L., Leger, A., Boulanger, F. 1985,Astr. Astrophys.,142, L19.ADSGoogle Scholar
  35. Roelfsema, P. R., Cox, P., Tielens, A. G. G. M.,et al. 1996,Astr. Astrophys.,315, L289.ADSGoogle Scholar
  36. Scoville, N. Z., Kwan, J. 1976,Astrophys. J.,206, 718.CrossRefADSGoogle Scholar
  37. Sellgren, K. 1984,Astrophys. J.,277, 623.CrossRefADSGoogle Scholar
  38. Siebenmorgen, R. 1993,Astrophys. J.,408, 218.CrossRefADSGoogle Scholar
  39. Siebenmorgen, R., Krugel, E. 1992,Astr. Astrophys.,259, 614.ADSGoogle Scholar
  40. Stecklum, B., Feldt, M., Richichi, A., Calamai, G., Lagage, P.O. 1997,Astrophys. J.,479, 339.CrossRefADSGoogle Scholar
  41. Thompson, R. I. 1984,Astrophys. J.,283, 165.CrossRefADSGoogle Scholar
  42. Volk, K., Cohen, M. 1989,Astr. J.,98, 931.CrossRefADSGoogle Scholar
  43. Yamashita, T., Sato, S., Nagata, T., Suzuki, H., Hough, J. H., McLean, I. S., Garden, R., Gatley, I. 1987,Astr Astrophys.,177, 258.ADSGoogle Scholar

Copyright information

© Indian Academy of Sciences 2000

Authors and Affiliations

  • S. K. Ghosh
    • 1
  • R. P. Verma
    • 1
  1. 1.Tata Institute of Fundamental ResearchMumbaiIndia

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