This program will study high velocity or explosive events simultaneously at temperatures ranging from the lower transition region to the corona.
The term explosive event has been used for a high velocity
phenomenon mainly studied in the C IV lines at 1550 A with HRTS. Their
properties are described by Dere (1994) and by Moses and Cook (1994)
and more thoroughly in number of earlier papers (see references in
Kjeldseth--Moe and Cheng 1994). Detailed knowledge is, however,
limited to their appearance in the lower transition region around T
10
K. Similar high velocity events at higher
temperatures extending into the corona was observed with the
slitless spectrograph SO82A on Skylab in 1973--74. Quantitative
measurements have been performed by Kjeldseth--Moe and Cheng (see
Kjeldseth--Moe and Cheng 1994, and references therein. See also the
table below.)
The main purpose of the proposed Joint Observing Program is to
determine whether the energetic high velocity events seen in the
corona and upper transition region is the same phenomenon as the
explosive events at T 10
K. The observations may
furthermore:
It has been hypothesised that such high velocity events are caused by magnetic reconnection in the solar atmosphere. Whether or not this is the case, they may be important for the energy and momentum input to the upper solar atmosphere. Their unusual properties may furthermore give important clues to understanding the structures and processes in the upper solar atmosphere.
References
Dere, K. P. 1994, Space Science Reviews, 70, 21.
Kjeldseth--Moe, O. and Cheng, C.-C. 1994, Space Science Reviews, 70, 85.
Moses, D. and Cook, J.W. 1994, Space Science Reviews, 70, 81.