Increase in the Amplitude of Line-of-sight Velocities of the Small-scale Motions in a Solar Filament before Eruption

We present a study on the evolution of the small-scale velocity field in a solar filament as it approaches the eruption. The observation was carried out by the Solar Dynamics Doppler Imager (SDDI) that was newly installed on the Solar Magnetic Activity Research Telescope at Hida Observatory. The SDD...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2017-07, Vol.843 (2), p.L24
Main Authors: Seki, Daikichi, Otsuji, Kenichi, Isobe, Hiroaki, Ishii, Takako T., Sakaue, Takahito, Hirose, Kumi
Format: Article
Language:English
Subjects:
AMPLITUDES
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CLOUDS
DISTRIBUTION
Eruptions
EVOLUTION
Histograms
Line of sight
MASS
Narrowband
PRECURSOR
Solar activity
SOLAR FLARES
Solar magnetic activity
Standard deviation
SUN
Sun: corona
Sun: coronal mass ejections (CMEs)
Sun: filaments, prominences
TELESCOPES
VELOCITY
Velocity distribution
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Summary:We present a study on the evolution of the small-scale velocity field in a solar filament as it approaches the eruption. The observation was carried out by the Solar Dynamics Doppler Imager (SDDI) that was newly installed on the Solar Magnetic Activity Research Telescope at Hida Observatory. The SDDI obtains a narrowband full-disk image of the Sun at 73 channels from H − 9.0 to H + 9.0 , allowing us to study the line-of-sight (LOS) velocity of the filament before and during the eruption. The observed filament is a quiescent filament that erupted on 2016 November 5. We derived the LOS velocity at each pixel in the filament using the Becker's cloud model, and made the histograms of the LOS velocity at each time. The standard deviation of the LOS velocity distribution can be regarded as a measure for the amplitude of the small-scale motion in the filament. We found that the standard deviation on the previous day of the eruption was mostly constant around 2-3 km s−1, and it slightly increased to 3-4 km s−1 on the day of the eruption. It shows a further increase, with a rate of 1.1 m s−2, about three hours before eruption, and another increase, with a rate of 2.8 m s−2, about an hour before eruption. From this result we suggest that the increase in the amplitude of the small-scale motions in a filament can be regarded as a precursor of the eruption.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/aa7559