Minifilament Eruption on the Quiet Sun. I. Observations at Hα Central Line

Abstract

The eruption of miniature filaments on the quiet Sun has been analyzed from time sequences of digital Hα filtergrams obtained at Big Bear Solar Observatory during 1997 September 18-24. The 2 days with the best image quality were selected for this initial study. During 13 hr of time-lapse observations on these 2 days, in an effective 640'' × 480'' area of quiet Sun close to the disk center, 88 erupting miniature filaments were identified. On average, these small-scale erupting filaments have a projected length of 19,000 km, an observed ejection speed of 13 km s-1, and a mean lifetime of 50 minutes from first appearance through eruption. The total mass and kinetic energy involved in a miniature filament eruption is estimated to be 1013 g and 1025 ergs, respectively. They are distinguished from macrospicules by the same criteria that large-scale filaments, before and during eruption, are distinguished from surges. Prior to eruption, one end, both ends, or the midsection of a miniature filament is superposed over a polarity reversal boundary on line-of-sight magnetograms. We conclude that miniature filaments are the small-scale analog to large-scale filaments.