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Y.-K. Ko, J. C. Raymond (Harvard-Smithsonian CfA), S. E. Gibson (HAO/NCAR), D. Alexander (Rice University), L. Strachan (Harvard-Smithsonian CfA), T. Holzer, H. Gilbert (HAO/NCAR), O. C. St. Cyr, B. J. Thompson (NASA/GSFC), C. D. Pike (Rutherford Appleton laboratory), J. Burkepile (HAO/NCAR), W. Thompson (L-3 Com/GSI), L. Fletcher (University of Glasgow)
A coronal jet occurred on August 26, 1999 at the NW limb near a sigmoid active region (AR8668). This jet was observed by several instruments at the limb (SOHO/CDS, SOHO/EIT, TRACE, MLSO/CHIP, MLSO/PICS) and at 1.64 Ro (SOHO/UVCS). At the limb, this jet event has both low and high temperature components. The high temperature component appeared at the early phase (first 20 minutes) of the event along with the low temperature component while the latter seems to last long (~ 1 hour) after the higher temperature component was gone. The line-of-sight motion at the limb started with red-shifted (by as much as 300 km/s) and turned blue-shifted (by as much as 200 km/s). At 1.64 Ro, the intensities of Ly\alpha, Ly\beta in the jet increased by a factor of several hundreds compared with the background corona. C III \lambda977 line also brightened significantly. This indicates low temperature (~1-2\times 105 K) emission in the jet, while the intensities of O VI \lambda1032 and O VI \lambda1037 increased by a factor of as large as 8. Both UVCS and CDS data show evidence of heating at the early phase of the event. The line-of-sight velocity seen at 1.64 Ro started with ~ 150 km/sec in blue shift and ended at ~ 100 km/sec in red shift. This is apparently opposite to what were observed when the jet emerged from the limb. The Doppler dimming analysis indicates that the radial outflow speed correlates with the magnitude of the line-of-sight speed. Interestingly, UVCS observations at 2.33 and 2.66 Ro show no trace of the jet and LASCO observations also yield no firm sight of the jet. In this paper, we present the observations by these instruments and discuss the dynamical structure and physical properties of this jet. Y.-K. Ko acknowledges the support by NASA grant NAG5-12865.
The author(s) of this abstract have provided an email address for comments about the abstract: yko@cfa.harvard.edu
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.