Detection and Characterization of Rotating Sunspots
Richard W. Nightingale (Lockheed Martin Advanced Technology Center, Palo Alto, CA)
As part of a statistical study of sunspots that rotate about their umbral centers in active regions, we have begun to analyze SOHO/MDI full-disk, synoptic magnetogram movies on a daily basis during solar maximum in cycle 23. We are analyzing these active regions when they are least distorted, within approximately +/- 30 degrees longitude of disk center. Many such active regions containing rotating sunspots have been identified. For example, our preliminary study found such active regions near disk center with one or more rotating sunspots for approximately two-thirds of the days in year 2000. Rotating sunspots result from looking temporally at perpendicular slices of a large, twisted magnetic flux tube penetrating through the photosphere from below the solar surface out into the solar corona. The twisted tube, or loop, carries energy via the Poynting flux density up into the corona, where some or all of the energy may be stored in the non-potentiality of the magnetic field to empower flares and coronal mass ejections. Coupling these findings of the presence of rotating sunspots on a majority of days during solar maximum with those from previous studies showing rotating sunspots associated with almost all of the X-flares since April 1998, and many of the M-flares, suggests that rotating sunspots could be providing much of the energy needed by the multitude of large X-ray flares occurring during the solar maximum period. Preliminary results of this study to date, as well as further discussion of detection and characterization of the rotating sunspots, will be presented.