Structure and oscillations in quiescent filaments from observations in Heiλ10830 å

✍ Scribed by Yi Zhang; Oddbjørn Engvold; Stephen L. Keil

• Book ID: 104648506
• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 823 KB
• Volume: 132
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00159130

✦ Synopsis

Observations of two quiescent filaments show oscillatory variations in Doppler shift and central intensity of the He I 210830 A. line.

The oscillatory periods range from about 5 to 15 rain, with dominant periods of 5, 9, and 16 rain. The 5-min period is also detected in the intensity variations, after correction for atmospheric effects. Doppler shifts precede intensity variations by about one period. The possibility that the oscillations are Alfv6n waves is discussed.

The Doppler signals of the filament form fibril-like structures. The fibrils are all inclined at an angle of about 25 ~ to the long axis of the filament. The magnetic field has a similar orientation relative to the major direction of the filament, and the measured Doppler signals are apparently produced by motions along magnetic flux tubes threading the filament.

The measured lifetimes of the small-scale fibrils of quiescent disk filaments are very likely a combined effect of intensity modulations and reshuffling of the structures.