Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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NON-LTE EFFECTS ON THE H3+ ROVIBRATIONAL POPULATION IN THE JOVIAN IONOSPHERE

  • Kim, Yong-Ha (Department of Astronomy and Space Science, Chungnam National University)
  • Received : 2012.01.03
  • Accepted : 2012.02.26
  • Published : 2012.04.30
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Abstract

We investigate non-LTE effects on the $H_3^+$ level populations to help the analysis of the observed 2 and 3.5 micron $H_3^+$ emissions from the Jovian ionosphere. We begin by constructing a simple three-level model, in order to compute the intensity ratio of the R(3,4) line in the hot band to the Q(1,0) line in the fundamental band, which have been observed in the Jovian auroral regions. We find that non-LTE effects produce only small changes in the intensity ratios for ambient $H_2$ densities less than or equal to $5{\times}10^{11}cm^{-3}$. We then construct two comprehensive models by including all the collisional and radiative transitions between pairs of more than a thousand known $H_3^+$ rovibrational levels with energies less than 10000 $cm^{-1}$. By employing these models, we find that the intensity ratios of the lines in the hot and fundamental bands are affected greatly by non-LTE effects, but the details depend sensitively on the number of collisional and radiative transitions included in the models. Non-LTE effects on the rovibrational population become evident at about the same ambient $H_2$ densities in the comprehensive models as in the three-level model. However, the models show that rotational temperatures derived from the intensities of rotational lines in the ${\nu}_2$ and $2{\nu}_2$ bands may differ significantly from the ambie temperatures in the non-LTE regime. We find that significant non-LTE effects appear near and above the $H_3^+$ peak, and that the kinetic temperatures in the Jovian thermospheric temperatures derived from the observed line ratios in the 2 and 3.5 micron $H_3^+$ emissions are highly model dependent.

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References

  1. Adams, N. G., Smith, D., & Alge, E. J. 1984, Measurements of Dissociative Recombination Coefficients of H3(+), HCO(+), N2H(+) and CH5(+) at 95 and 300K Using the FALP Apparatus , Chem. Phs., 81, 1778
  2. Dickinson, A. S., Phillips, T. G., Goldsmith, P. F., Percival, L. C., & Richards, D. 1977, Rotational Excitation of Molecules by Electrons in Interstellar Clouds, A&A, 54, 645
  3. Drossart, P., & 11 Colleagues. 1989, Detection of $H^{+}_{3}$ on Jupiter, Nature, 340, 539 https://doi.org/10.1038/340539a0
  4. Grodent, D., Waite, Jr. J. H., & Gerard, J.-C. 2001, A Self- Consistent Model of the Jovian Auroral Thermal Structure, J. Geophys. Res., 106, 12933 https://doi.org/10.1029/2000JA900129
  5. Johnsen, R., & Guberman, S. L. 2010, Chapter 3. Dissocia- tive Recombination of $H^{+}_{3}$ Ions with Electrons: Theory and Experiment, Advances in Atomic, Molecular, and Optical Physics, 59, 75 https://doi.org/10.1016/S1049-250X(10)59003-7
  6. Kim, Y. H., Fox, J. L., & Porter, H. S. 1992, Densities and Vibrational Distribution of $H^{+}_{3}$ in the Jovian Auroral Ionosphere, J. Geophys. Res., 97, 6093 https://doi.org/10.1029/92JE00454
  7. Kim, Y. H., Pesnell, W. D., Grebowsky, J. M., & Fox, J. L. 2001, Meteoric Ions in the Ionosphere of Jupiter, Icarus, 150, 261 https://doi.org/10.1006/icar.2001.6590
  8. Kokoouline, V., Faure, A., & Tennyson, J. 2010, Calcula- tion of Rate Constatns for Vibrational and Rotational Excitation of the $H^{+}_{3}$ Ion by Electron Impact, MNRAS, 405, 1195
  9. Kreckel, H., & 22 Co-Authors. 2005, High-Resolution Dis- sociative Recombination of Cold $H^{+}_{3}$ and First Evidence for Nuclear Spin Effects, PRL, 95, 263201 https://doi.org/10.1103/PhysRevLett.95.263201
  10. Lam, H. A., Achilleos, N., Miller, S., Tennyson, J., Trafton, L. M., Geballe, T. R., & Ballester, G. E. 1997, A Baseline Spectroscopic Study of te Infrared Auroras of Jupiter, Icarus, 127, 379 https://doi.org/10.1006/icar.1997.5698
  11. Leu, M. T., Biondi, M. A., & Johnsen, R. 1973, Measure- ments of Recombination of Electrons with $H^{+}_{3}$ and $H^{+}_{5}$ Ions, Phys. Rev. A. 8, 413 https://doi.org/10.1103/PhysRevA.8.413
  12. Lindsay, C. M., & McCall, B. J. 2001, Comprehensive Eval- uation and Compilation of $H^{+}_{3}$ Spectroscopy, J. Mol. Spec., 219, 60
  13. Maillard, J.-P., Drossart, P., Watson, J. K. G., Kim, S. J., & Caldwell, J. 1990, $H^{+}_{3}$ Fundamental Band in Jupiter's Auroral Zones at High Resolution from 2400 to 2600 In- verse Centimeters, ApJ, 363, 37 https://doi.org/10.1086/185859
  14. Melin, H., Miller, S., Stallard, T., & Grodent, D. 2005, Non-LTE Effects on $H^{+}_{3}$ Emission in the Jovian Upper Atmosphere, Icarus, 178, 97 https://doi.org/10.1016/j.icarus.2005.04.016
  15. Miller, S., Archilleos, N., Ballester, G. E., Lam, H., Ten- nyson, J., Geballe, T. R., & Trafton, L. M. 1997, Mid- To-Low Latitudes $H^{+}_{3}$ Emission from Jupiter, Icarus, 130, 57 https://doi.org/10.1006/icar.1997.5813
  16. Neale, L., Miller, S., & Tennyson, J. 1996, Spectroscopic Properties of the $H^{+}_{3}$ Molecule: a New Calculated Line List, ApJ, 464, 516 https://doi.org/10.1086/177341
  17. Oka, T., & Epp, E. 2004, The Nonthermal Rotational Dis- tribution of $H^{+}_{3}$ , ApJ, 613, 349 https://doi.org/10.1086/423030
  18. Perry, J. J., Kim, Y. H., & Fox, J. L. 1999, Chemistry of the Jovian Auroral Ionosphere, Journ. Geophys. Res., 104, 16, 541
  19. Plasil, R., Glosik, J., Poterya, V., Kudrna, P., Rusz, J., & Tichy, M. 2002, Advanced Integrated Stationary After- glow Method for Experimental Study of Recombination of Processes of $H^{+}_{3}$ and $D^{+}_{3}$ Ions with Electrons, Int. J. Mass Spect., 218, 105 https://doi.org/10.1016/S1387-3806(02)00714-5
  20. Raynaud, E., Lellouch, E., Maillard, J.-P., Gladstone, G. R., Waite, Jr. J. H., Bezard, B., Drossart, P., & Fouchet, T. 2004, Spectros-Imaging Observations of Jupiter's 2 Micron Auroral Emission. I. $H^{+}_{3}$ Distribution and Tem- perature, Icarus, 171, 133 https://doi.org/10.1016/j.icarus.2004.04.020
  21. Stallard, T., Miller, S., Millward, G., & Joseph, R. D. 2002, On the Dynamics of the Jovian Ionosphere and Thermo- sphere II. The Measurement of $H^{+}_{3}$ Vibrational Temper- ature, Column Density, and Total Emission, Icarus, 156, 498 https://doi.org/10.1006/icar.2001.6793