On Magnetic Twist And Writhe in Solar Active Regions

Using vector magnetic field data taken by the HMI/SDO, we study magnetic twist and writhe in solar emerging active regions. Magnetic twist in an active region is inferred by a constant force-free alpha calculated from the observed vector magnetic field data; the writhe is computed from the tilt of the active region. Evolution of the twist and writhe in active regions during their emergence is studied, and possible relationship between them is explored. The result has potential to provide information that helps diagnose generation of twist and writhe in active regions.