Abstract
During operations on the Spacelab-2 Shuttle mission, the NRL High Resolution Telescope and Spectrograph (HRTS) recorded spectra of a variety of solar features in the 1200–1700 Å wavelength region which contains spectral lines and continua well suited for investigating the temperature minimum, the chromosphere and transition zone. These data show that, at the highest spatial resolution, the transition zone spectra are broken up from a continuous intensity distribution along the slit into discrete emission elements. The average dimensions of these discrete transition zone structures is 2400 km along the slit, but an analysis of their emission measures and densities shows that the dimensions of the actual emitting volume is conciderably less. If these structures are modelled as an ensemble of subresolution filaments, we find that these filaments have typical radii of from 3 to 30 km and that the cross-sectional fill factor is in the range from 10−5 to 10−2. The transport of mass and energy through these transition zone structures is reduced by this same factor of 10−5 to 10−2 which has significant consequences for our understanding of the dynamics of the solar atmosphere. Because the HRTS transition zone line profiles are not broadened by resolved large-spatial-scale solar velocity fields, the line widths of the Civ lines have been analyzed. The average line width is 0.195 Å (FWHM) and requires an average nonthermal velocity of 16 km s−1 (most-probable) or 19 km s−1 (root-mean-square) which is lower than previously observed values.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Athay, R. G. and White, O. R.: 1980, Astrophys. J. 240, 306.
Bartoe, J.-D. F. and Brueckner, G. E.: 1975, J. Opt. Soc. Am. 65, 13.
Boland, B. C., Dyer, E. P., Firth, J. G., Gabriel, A. H., Jones, B. B., Jordan, C., McWhirter, R. W. P., Monk, P., and Turner, R. F.: 1975, Monthly Notices Roy. Astron. Soc. 171, 697.
Bonnet, R. M., Bruner, E. C., Acton, L. W., Brown, W. A., Decaudin, M., and Foing, B.: 1982, Astron. Astrophys. 111, 125.
Brueckner, G. E.: 1980, Highlights of Astronomy 5, 557.
Bruner, E. C. and McWhirter, R. W. P.: 979, Astrophys. J. 231, 557.
Cook, J. W., Brueckner, G. E., and Bartoe, J.-D. F.: 1983, Astrophys. J. 270, L89.
Davila, J. M.: 1987, Astrophys. J. 317, 514.
Dere, K. P.: 1982, Solar Phys. 75, 189.
Dere, K. P., Bartoe, J.-D. F., and Brueckner, G. E.: 1982, Astrophys. J. 259, 366.
Dere, K. P., Bartoe, J.-D. F., and Brueckner, G. E.: 1983, Astrophys. J. 267, L65.
Dere, K. P., Bartoe, J.-D. F., and Brueckner, G. E.: 1984, Astrophys. J. 281, 870.
Dere, K. P., Bartoe, J.-D. F., and Brueckner, G. E.: 1986, Astrophys. J. 305, 947.
Dufton, P. L., Hibbert, A., Kingston, A. E., and Doscheck, G. A.: 1982, Astrophys. J. 257, 338.
Einaudi, G. and Mok, Y.: 1987, Astrophys. J. 319, 520.
Feldman, U., Doschek, G. A., and Patterson, N. P.: 1976, Astrophys. J. 209, 270.
Flower, D. R. and Hussbaumer, H.: 1975, Astron. Astrophys. 45, 145.
Kjeldseth Moe, O. and Nicolas, K. R.: 1917, Astrophys. J. 211, 579.
Kjeldseth Moe, O., VanHoosier, M. E., Bartoe, J.-D. F., and Brueckner, G. E.: 1976, NRL Report, No. 8057.
Rabin, D. and Moore, R.: 1984, Astrophys. J. 285, 359.
Simon, G., Mein, P., Vial, J. C., Shine, R. A., and Woodgate, B. E.: 1982, Astron. Astrophys. 115, 367.
Withroe, G. L. and Noyes, R. W.: 1977, Ann. Rev. Astron. Astrophys. 15, 363.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Dere, K.P., Bartoe, JD.F., Brueckner, G.E. et al. Discrete subresolution structures in the solar transition zone. Sol Phys 114, 223–237 (1987). https://doi.org/10.1007/BF00167342
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00167342