The evolution from birth to decay of a short-lived active region

In the following paper we present results of the analysis of NOAA active re gion 7968, which was the target of a coordinated observing campaign involvi ng the instruments aboard the Solar and Heliospheric Observatory (SOHO), Yo hkoh, and ground-based observatories (Bialkow, Pic du Midi, and Huairou). T his active region was relatively short-lived, and thus provides a rare exam ple of a region observed continuously from its birth to its decay phase. We have extrapolated the SOHO Michelson Doppler Imager (MDI) longitudinal mag netograms, and have compared the results of the modeled field with loops ob served over a wide range of temperatures (similar to 10(5)-3 x 10(6) K). We find that, throughout the interval of disk passage, the global magnetic st ructure of the active region corresponds to a nearly potential-field config uration. Magnetic field sheer is only seen in isolated patches along the po larity inversion line and is associated with the emergence of parasitic pol arity regions. Several small GOES (B-crass) X-ray flares and surge-like eje ctions were observed during the lifetime of the active region. We interpret both the heating of the active region loops and the flaring in terms of ma gnetic reconnection. In our scenario, the hares are assumed to be due to re connection between the pre-existing field and newly emerging twisted flux t ubes (as indicated by observed changes in the transverse field and inferred twisting motions of the plasma); while the heating of the plasma in quasi- static active region loops is assumed to be due to a relaxation process of the magnetic configuration. These loops appear anchored at places where the photospheric field is highly fragmented, creating a very complex connectiv ity pattern. This fact, together with the continual photospheric motions, p rovides the favorable conditions for current sheet formation and release of magnetic energy.