Evidence of rapid flux emergence associated with the M8.7 flare on 2002 July 26

In this paper, we present a detailed study of the M8.7 flare that occurred on 2002 July 26 using data from the Big Bear Solar Observatory (BBSO), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), the Transition Region and Coronal Explorer (TRACE), and the Solar and Heliospheric Observatory (SOHO). This flare has interesting properties similar to a number of flares that we studied previously, such as a rapid increase of magnetic flux in one polarity and an increase in transverse fields and magnetic shear associated with the flare. However, this event had the most comprehensive observations; in particular, the high-resolution high-cadence BBSO vector magnetograph observations. At the time of the flare, across the flare neutral line, there was a sudden emergence of magnetic flux at the rate of 10²⁰ MX hr ¹ in both the longitudinal and transverse components. The emerging flux mostly occurred at the sites of the flare. It was very inclined and led to impulsively enhanced shear in the magnetic fields. We discuss these observations in the context of magnetic reconnection triggered by rapid flux emergence. It is also possible that the new flux signifies flare-related change in the field line inclination.