SUMER Observations of Coronal-Hole Temperatures
- 190 Downloads
Observations of emission lines in the vacuum-ultraviolet spectral range with calibrated instrumentation provide crucial information on the prevailing plasma temperatures in the solar atmosphere. Coronal-hole temperatures measured by the SUMER spectrometer on SOHO will be presented in this contribution. Electron temperatures can be estimated from the formation temperatures of the observed emission lines. Line-ratio and emission-measure analyses, however, offer higher accuracies. Typical electron temperatures at altitudes of H<200 Mm in coronal holes are below 1 MK in bright structures—the coronal plumes—with higher values in darker areas—the inter-plume regions. Line-width measurements yield effective ion temperatures, which are much higher than the electron temperatures. Observations of line profiles emitted from species with different masses allow a separation of the effective temperatures into ion temperatures and unresolved non-thermal motions along the line of sight.
KeywordsSolar vacuum-ultraviolet observations Coronal-hole temperatures
Unable to display preview. Download preview PDF.
- E. Antonucci, G. Noci, J.L. Kohl, G. Tondello, M.C.E. Huber, S. Giordano, C. Benna, A. Ciaravella, S. Fineschi, L.D. Gardner, R. Martin, J. Michels, G. Naletto, P. Nicolosi, A. Panasyuk, J.C. Raymond, M. Romoli, D. Spadaro, L. Strachan, A. van Ballegooijen, ASP Conf. Ser. 118, 273–277 (1997) ADSGoogle Scholar
- J.T. Mariska, The Solar Transition Region (University Press Cambridge, Cambridge, 1992) Google Scholar
- K. Wilhelm, in Proc. 3rd SOLTIP Symp. (Academic Publ., Beijing, 1998), pp. 75–80 Google Scholar
- K. Wilhelm, in Landolt-Börnstein, ed. by J.E. Trümper. New Series VI, vol. 4B (Springer, Berlin, 2009), pp. 90–96 Google Scholar
- K. Wilhelm, L. Abbo, F. Auchère, N. Barbey, L. Feng, A.H. Gabriel, S. Giordano, S. Imada, A. Llebaria, W.H. Matthaeus, G. Poletto, N.-E. Raouafi, S.T. Suess, L. Teriaca, Y.-M. Wang, Astron. Astrophys. Rev. (2010, submitted) Google Scholar