Jets or high velocity flows revealed in high-cadence spectrometer and imager co-observations?

摘要

We report on active region EUV dynamic events observed simultaneously athigh-cadence with SUMER/SoHO and TRACE. Although the features appear in theTRACE Fe ix/x 171A images as jets seen in projection on the solar disk, theSUMER spectral line profiles suggest that the plasma has been driven along acurved large scale magnetic structure, a pre-existing loop. The SUMERobservations were carried out in spectral lines covering a large temperaturerange from 10^4 K to 10^6 K. The spectral analysis revealed that a suddenheating from an energy deposition is followed by a high velocity plasma flow.The Doppler velocities were found to be in the range from 90 to 160 km/s. Theheating process has a duration which is below the SUMER exposure time of 25 swhile the lifetime of the events is from 5 to 15 min. The additional check onsoft X-ray Yohkoh images shows that the features most probably reach 3 MK(X-ray) temperatures. The spectroscopic analysis showed no existence of coldmaterial during the events.