Production of a short-lived filament by a surge

Abstract

A large surge was observed on September 17, 1971, part of which, after travelling 200 000 km through the corona, returned to the surface to form a filament. The filament lasted about 30 min, then rose up and returned to the source of the surge. We interpret this as the filling of a semi-stable magnetic trap. The energetics of radio, X-ray, and surge expulsion are estimated. The radio spectrum and flux correspond to a thermal source of area 4 (arcmin)², T ∼ 190 000 K, N²_e V ∼ 7 × 10⁴⁸, which is optically deep at 8800 MHz. The soft X-ray source has T ∼ 12 × 10⁶ K, N²_e V ∼ 3 × 10⁴⁸; and if an equal mass is expelled in the surge, the kinetic energy of the surge is similar to the thermal energy of the X-ray source.

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