The bottom line is that at this stage in solar physics we do not really know what produces a flare nor what produces a CME. There are competing theories, but all tend to have deficiencies with respect to matching the observational evidence. We certainly believe that they all depend on the reconfiguration of magnetic fields as their primary energy source, but in the final analysis, we really only believe this because we can conceive of no other solar energy source of sufficient magnitude.
3. What are the characteristics of Hyder flares?
As previously mentioned, the name Hyder flare is given to a flare that occurs away from an active region or sunspot group and that is associated with the sudden disappearance of a dark filament. The appearance of these flares can range from a string of bright knots on one or both sides of the filament (or rather, the position previously occupied by the filament, sometimes called the filament channel), to a single or double ribbon flare. The ribbons are parallel to the filament channel. If only one ribbon is present, it will lie to one side of the channel, whereas if two parallel ribbons occur, one ribbon will lie on one side of the filament channel, and the other ribbon will lie on the opposite side.
One interesting characteristic of Hyder flares is that they usually develop or rise to maximum brightness much more slowly than do the more common flares associated with active regions. The larger Hyder flares may take 30 to 60 minutes to rise to a peak intensity, and then they may last for several hours. Although they may attain a large area, they usually have a relatively low intensity. Thus, classifications for a large Hyder flare may read 2F, 2N or possibly even 3F. This contrasts to an active region flare in which 3F is very rare. An active region flare that attains sufficient area to put it into the importance class 3, will invariably have either a Normal or more usually a Brilliant brightness classification.
X-ray flares and radio (microwave) bursts associated with the optical Hyder flare, are also generally long lived phenomenon and are classified as the gradual rise and fall type of event (in contrast to the impulsive and complex events associated with large active region flares).
Generally Hyder flares are not associated with energetic particle emission or geomagnetic storms (implying that they may not be associated with a coronal mass ejection). However, this is not always the case, as a large halo CME observed by the LASCO solar coronagraph on board the SOHO spacecraft was most definitely associated with a Hyder flare (2N/M1) observed on 12 September 2000. This same complex also appeared to have produced energetic protons at geosynchronous orbit with energies in excess of 100 MeV, and in substantial numbers at energies of 10 MeV. It is believed that the sudden storm commencement observed at 0450UT 15 September, and the subsequent minor geomagnetic storm was produced by this particular CME.
4. What produces Hyder flares?
Hyder's explanation of the flare type now named after him depended on the observational evidence that (1) often the flare was a parallel ribbon flare with one ribbon each side of the filament channel, and (2) that geomagnetic storms were not associated with these flares. This led to the speculation that the filamentary material was not ejected far into the corona, but in fact fell back to the chromosphere producing the flare.