Proton Flare in AR 8210

Science nugget: Sept 09, 1998

From a two-week period starting late April 1998, there were many intense flares from AR 8210, and several of them were proton flares according to interplanetary observations. BATSE data for those flares show their spectra progressively hardening (Alan Kiplinger). One such flare was the one on 9-May-98. This flare was well observed by Yohkoh. Its hard X-ray time profiles from HXT are shown below. Their energy ranges are (from top to bottom) 14-23 keV, 23-33 keV and 33-53 keV. (Click on the picture to see a larger, more visible, version.)

Note that the lowest curve is quite different from the highest curve. Also, the variations are not very sharp. These may be indications of something different from impulsive flares. Although yohkoh workers feel that they have not observed what is called a ``type-C'' flare, a nomenclature from the Hinotori observations, the present flare may belong to that category and similar flares have been observed many times, especially in this cycle.

It is reasonable to speculate that a flare of this type is eruptive. This particular flare, which took place on the west limb, was indeed eruptive.  The FOV is 5.2 arcmin.  View the movie here.

The disk transit of this flare-productive reigion is shown in the movie here.  The FOV is 10.4 arcmin.  Note that this event was also observed at Nobeyama Observatory .

Nariaki Nitta 6-Sep-98 (email 'nitta'