전리수소 영역의 물리량 측정을 위한 방출선 모형연구

  • Received : 2010.11.29
  • Accepted : 2010.12.23
  • Published : 2011.03.31


A diagnostic tool has been proposed to convert the observed surface distribution of hydrogen recombination line intensities into the radial distributions of the electron temperature and the density in HII regions. The observed line intensity is given by an integral of the volume emission coefficient along the line of sight, which comprises the Abel type integral equation for the volume emission coefficient. As the emission coefficient at a position is determined by the temperature and density of electrons at the position, the local emission coefficient resulted from the solution of the Abel equation gives the radial distribution of the temperature and the density. A test has been done on the feasibility of our diagnostic approach to probing of HII regions. From model calculations of an HII region of pure hydrogen, we have theoretically generated the observed surface brightness of hydrogen recombination line intensities and analyzed them by our diagnostic tool. The resulting temperatures and densities are then compared with the model values. For this case of uniform density, errors in the derived density are not large at all the positions. For the electron temperature, however, the largest errors appear at the central part of the HII region. The errors in the derived temperature decrease with the radial distance, and become negligible in the outer part of the model HII region.


  1. Arfken, G., 1970, in Mathematical Methods for Physicists (Academic Press)
  2. Canto, J., Elliott, K. H., Meaburn, J. M., & Theokas, A. C., 1980, On the Derivation of Electron Density and Temperature from SII and OII Forbidden Line Intensity Ratios, MNRAS, 193, 911
  3. Chaisson, E. J. & Dopita, M. A., 1977, A Comparison of the Orion Nebula's Physical Conditions Measured in the Radio and Optical Domains, A&A, 56, 385
  4. Dinerstein, H. L., Lester, D. F., & Werner, M. W., 1985, Far-Infrared Line Observations of Planetary Nebulae. I - The Forbidden OIII Spectrum, ApJ, 291, 561
  5. Gordon, M. A., 1969, A Radio Study of the HII Region Orion B, ApJ, 158, 479
  6. Harrington, J. P., Seaton, M. J., Adames, P. S., & Lutz, J. H., 1982, Ultraviolet Spectra of Planetary Nebulae. VI - NGC 7662, MNRAS, 199, 517
  7. Hong, S. S. & Sung, H. I., 1989, Effects of the Diffuse Ionizing Radiation on the Structure of HII Regions, JKAS, 22, 127
  8. Hummer, D. G. & Storey, P. J., 1987, Recombination-Line Intensities for Hydrogenic Ions. I - Case B Calculations for HI and HeII, MNRAS, 224, 801
  9. Kaler, J. B., 1986, C(+2) Electron Temperatures in Planetary Nebulae, ApJ, 308, 337
  10. Kim, D. W. & Hong, S. S., 1982, Distributions of Density, Temperature and Abundances in the Orion Nebula, JKAS, 15, 9
  11. Osterbrock, D. E., 1989, in Astrophysics of Gaseous Nebulae and Active Galactic Nuclei (Univ. Sci. Books: Mill Valley, CA)
  12. Panagia, N., 1973, Some Physical Parameters of Early-Type Stars, AJ, 78, 929
  13. Perrenod, S. C., Shields, G. A., & Chaisson, E. J., 1977, Observation and Interpretation of Temperature Gradients in the Orion Nebula, ApJ, 216, 427
  14. Ritzerveld, J., 2005, The Diffuse Nature of Stromgren Spheres, A&A, 439, 23
  15. Rubin, R. H., 1968, The Structure and Properties of HII Regions, ApJ, 153, 761
  16. Rubin, R. H., Hollenbach, D. J., & Erickson, E. F., 1983, Modeling of G333.6-0.2 as a Spherical HII Region, ApJ, 265, 239
  17. Shaver, P. A., 1970, Electron Temperatures of HII Regions, ApL, 5, 167
  18. Shaver, P. A., McGee, R. X., Newton, L. M., Danks, A. C., & Pottasch, S. R., 1983, The Galactic Abundance Gradient, MNRAS, 204, 53
  19. Simpson, J. P. & Rubin, R. H., 1984, Models of Four Highly Obscured Compact HII Regions, ApJ, 281, 184
  20. Spitzer, L., 1978, in Physical Processes in the Interstellar Medium (Wiley Inc.: New York)