Evolutionary Characteristics of Magnetic Helicity Injection through Active Regions Hyewon Jeong, Jongchul Chae Seoul National University
Purpose • How much helicity is supplied through active regions? • Does the helicity injection in an active region occurs intensively during a specific period or steadily through all of its lifetime?
Magnetic Helicity • Magnetic helicity Sum of linking numbers over all pairs of closed field lines in a given volume • Relative magnetic helicity Magnetic helicity relative to the helicity of potential field with the same magnetic flux at the photospheric boundary
Method (Chae’s method) • Helicity transfer equation • Apparent horizontal velocity of field line footpoint : ( LCT method) • Normal component of photospheric magnetic field : (line-of-sight magnetogram data) • Vector potential for : (Fourier Transform method)
Data and application • line-of-sight magnetogram data (SoHO/MDI) • 96min cadence • calculation for about 5 days away from the limb • 6 active regions
AR 10696 1st rotation 2nd rotation
AR 10365 1st rotation 2nd rotation
Conclusion • Magnetic helicity is supplied intensively during the growth of active regions or during flux emergence. • The range of the amount of helicity injected : • The maximum helicity injection rate measured :