Periodic Motion along a Solar Filament Initiated by a Subflare

Abstract

A type of mass motion in solar filaments, not previously reported, is studied with high-cadence (1 minute) Hα observations made at the Big Bear Solar Observatory on 2001 October 24. This oscillatory motion is along the filament and extends over a long distance (~1.4 × 105 km) with a period of ~80 minutes and a very high velocity amplitude of ~92 km s-1. Another significant property of this oscillation is that it is triggered by a subflare that occurred near its footpoint. The oscillation completes three cycles before it damps out over a timescale of ~210 minutes. We mainly discuss whether this oscillation is an extreme form of the recently discovered counterstreaming flows in filaments or is a form of the large-amplitude filament oscillations (known as a "winking" filament) discovered a half-century ago.