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J. Chae, J. Qiu, H. Wang, P. R. Goode (Big Bear Solar Observatory, New Jersey Institue of Technology)
We analyzed simultaneous EUV data from the Transition Region And Coronal Explorer (TRACE) and H\alpha data from Big Bear Solar Observatory (BBSO). In the active region studied, we found several EUV jets that repeatedly occurred where pre-existing magnetic flux was canceled by newly emerging flux of opposite polarity. The jets look like, but are usually smaller and shorter lived than Yohkoh soft X-ray jets. The EUV jets have a typical size of 4000-10,000 km, a transverse velocity of 50-100 km s-1, and a lifetime of 2-4 minutes. Each of the jets was ejected from a loop-like bright EUV emission patch at the moment when the patch reached its peak emission. We also found dark H\alpha surges that are correlated with these jets. A careful comparison, however, revealed that the H\alpha jets are not cospatial with the EUV jets. Instead, the EUV jets are are identified with bright jetlike features in the H\alpha line center, which are distinct from dark surges. Our results support a picture in which H\alpha surges and EUV jets represent different kinds of plasma ejection --- cool and hot plasma ejections along different field lines --- which must be dynamically connected to each other. We emphasize the importance of observed flux cancellation and a small erupting filament in understanding the acceleration mechanisms of EUV jets and H\alpha surges. This work is partially supported by NSF under grant ATM-97-14796 and NASA under grants NAG5-4919, NAG5-7349, and NAG5-7350 to BBSO.
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s follows:
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJL/v513n1/985846/sc0.html