Abstract
Line-width measurements of the coronal ion Siviii confirm earlier observations which show an increase in the non-thermal velocity above the solar limb. The present data, taken at the equatorial limb, show an increase from 24 km s-1 at the limb to 28 km s-1 some 25000 km above the limb. The electron density as measured from the Siviii line pair shows a decrease from 3.5 × 108 cm-3 to 1.8 × 108 cm-3 over the same distance. These data imply that the non-thermal velocity is inversely proportional to the quadratic root of the electron density, in excellent agreement with that predicted for undamped radially propagating Alfvén waves.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bruner, M. E. and McWhirter, R. W. P.: 1979, Astrophys. J. 231, 557.
Dere, K. P., Landi, E., Mason, H. E., Monsignori-Fossi, B., and Young, P. R.: 1997, Astron. Astrophys. Suppl. 125, 149.
Doschek, G. A., Feldman, U., and Cohen, L.: 1977, Astrophys; J. Suppl. 33, 10.
Doschek, G. A., Warren, H. P., Laming, J. M., Mariska, J. T., Wilhelm, K., Lemaire, P., Schuhle, U., and Moran, T. G.: 1997, Astrophys. J. 482, L109.
Erdélyi, R., Doyle, J. G., and Perez, M. E.: 1998, Astron. Astrophys., submitted.
Feldman, U., Doschek, G. A., Mariska, J. T., Bhatia, A. K., and Mason, H. E.: 1978, Astrophys. J. 226, 674
Hassler, D. M., Rottman, G. J., Shoub, E. C., and Holzer, T. E.: 1990, Astrophys J. 348, L77.
Laming, J. M., Feldman, U., Schuhle, U., Lemaire, P., Curdt, W., and Wilhelm, K.: 1997, Astrophys J. 485, 911.
Lou, Y. Q. and Rosner, R.: 1994, Astrophys J. 424, 429.
Lou, Y. Q.: 1996, Monthly Notices Royal Astron. Soc. 281, 750.
Mariska, J. T.: 1992, The Solar Transition Region, Cambridge University Press, Cambridge.
Mariska, J. T., Feldman, U., and Doschek, G. A.: 1978, Astrophys J. 226, 698.
Nicolas, K. R., Brueckner, G. E., Tousey, R., Tripp, D. A., White, O. R., and Athay, R.: 1977, Solar Phys. 55, 305.
Roussel-Dupré, R., Francis, M. H., and Billings, D. E.: 1979, Monthly Notices Royal Astron. Soc. 187, 9.
Seely, J. F., Feldman, U., Schuhle, U., Wilhelm, K., Curdt, W., and Lemaire, P.: 1997, Astrophys J. 484, L87.
Siegmund, O. H. W., Gummin, M. A., Stock, J. M., Marsh, D., Raffanti, T., Sasseen, T., Tom, J., Welsh, B., Gaines, G. A., Jelinsky, P., and Hull, J.: 1994, Proc SPIE 2280, 89.
Wilhelm, K., Curdt, W., Marsch, E., Schúhle, U., Lemaire, P., Gabriel, A., Vial, J.-C., Grewing, M., Huber, M. C. E., Jordan, S. D., Poland, A. I., Thomas, R. J., Kúhne, M., Timothy, J. G., Hassler, D. M., and Siegmund, O. H. W.: 1995, Solar Phys. 162, 189.
Wilhelm, K., Curdt, W., Marsch, E., Schuhle, U., Lemaire, P., Gabriel, A., Vial, J.-C., Grewing, M., Huber, M. C. E., Jordan, S. D., Poland, A. I., Thomas, R. J., Kuhne, M., Timothy, J. G., Hassler, D. M., and Siegmund, O. H. W.: 1997a, Solar Phys. 162, 189.
Wilhelm, K., Lemaire, P., Curdt, W., Schuhle, U., Marsch, E., Poland, A. I., Jordan, S. D., Thomas, R. J., Hassler, D. M., Huber, M. C. E., Vial, J.-C., Kuhne, M., Siegmund, O. H. W., Gabriel, A., Timothy, J. G., Grewing, M., Feldman, U., Hollandt, J., and Brekke, P.: 1997b, Solar Phys. 170, 75.
Withbroe, 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
Doyle, J.G., Banerjee, D. & Perez, M.E. Coronal line-width variations. Solar Physics 181, 91–101 (1998). https://doi.org/10.1023/A:1005019931323
Issue Date:
DOI: https://doi.org/10.1023/A:1005019931323