Back to Volume
Paper: Polar Magnetic Field Depth as Derived from SoHO EIT Polar Plumes Observations
Volume: 184, Third Advances in Solar Physics Euroconference: Magnetic Fields and Oscillations
Page: 334
Authors: Makarov, V. I.; Callebaut, D. K.; Cugnon, P.
Abstract: The polar corona of the Sun was analysed using the SoHO EIT images at 17.1 nm during June 1, 1997 - June 24, 1998 and the solar eclipses during 1871 - 1997. The depth of the "solar magnet" (SM) or q(t,r) as the distance from the center of the Sun to the intersection of the tangents to the polar coronal plumes at their base at the limb was found. According to the eclipse observations q(t,r) is about (0.45 +/- 0.05) R_sun in the solar maximum and (0.65 +/- 0.05) R_sun in the solar minimum. According to the SoHO observations q(N) = (0.67 +/- 0.02) R_sun and q(S) = (0.71 +/- 0.02) R_sun during the minimum activity for 1996, March - October (N for North, S for South). With increase of the solar activity in 1997-1998 the value of q(N,t,r) decreases to (0.52 +/- 0.02) R_sun in the Northern hemisphere and to (0.40 +/- 0.02) R_sun in the Southern hemisphere whereas the Wolf number increases from 12 to 70.0. A North-South asymmetry Q(t,r) = q(N) - q(S) = - 0.06 (solar radius as unit) has been negative during June 1, 1997 - February 10, 1998 and then it gradually increased and attained a maximum Q(t,r) = 0.17 in mid of May, 1998. An anticorrelation between < q(N) - q(S), W(N)-W(S) > and < W(t), q (t,r) > was found. The relationship between the depth of the "solar magnet" and polar ring - filaments is discussed.
Back to Volume