Coronal loop oscillations observed with the Transition region and Coronal explorer

We report here, for the first time, on spatial oscillations of coronal loop s, which were detected in extreme-ultraviolet wavelengths (171 Angstrom) wi th the Transition Region and Coronal Explorer, in the temperature range of T-e approximate to 1.0-1.5 MK. The observed loop oscillations occurred duri ng a flare that began at 1998 July 14, 12:55 UT and are most prominent duri ng the first 20 minutes. The oscillating loops connect the penumbra of the leading sunspot to the flare site in the trailing portion. We identified fi ve oscillating loops with an average length of L = 130,000 +/- 30,000 km. T he transverse amplitude of the oscillations is A = 4100 +/- 1300 km, and th e mean period is T = 280 +/- 30 a. The oscillation mode appears to be a sta nding wave mode (with fixed nodes at the footpoints). We investigate differ ent MHD wave modes and find that the fast kink mode with a period tau = 205 (L/10(10) cm)(n(e)/10(9) cm(-3))(1/2) (B/10 G)(-1) s provides the best agre ement with the observed period. We propose that the onset of loop oscillati ons in distant locations is triggered by a signal or disturbance that propa gates from the central hare site with a radial speed of approximate to 700 km s(-1). Because the observed loop oscillation periods are comparable to p hotospheric 5 minute oscillations, a resonant coupling between the two syst ems is possible. We further find evidence for global extreme-UV dimming in the entire active region possibly associated with a coronal mass ejection.