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Title: High-resolution Observations of Downflows at One End of a Pre-eruption Filament

Abstract

Studying the dynamics of filaments at the pre-eruption phase can shed light on the precursor of eruptive events. Such high-resolution studies (of the order of 0.″1) are highly desirable yet very rare. In this work, we present a detailed observation of a pre-eruption evolution of a filament obtained by the 1.6 m New Solar Telescope (NST) at the Big Bear Solar Observatory (BBSO). One end of the filament is anchored at the sunspot in the NOAA active region (AR) 11515, which is well observed by NST H α off-bands from four hours before to one hour after the filament eruption. A M1.6 flare is associated with the eruption. We observed persistent downflowing materials along the H α multi-threaded component of the loop toward the AR end during the pre-eruption phase. We traced the trajectories of plasma blobs along the H α threads and obtained a plane-of-sky velocity of 45 km s{sup −1} on average. Furthermore, we estimated the real velocities of the downflows and the altitude of the filament by matching the observed H α threads with magnetic field lines extrapolated from a nonlinear force-free field model. Observations of chromospheric brightenings at the footpoints of the falling plasma blobs aremore » also presented. The lower limit of the kinetic energy per second of the downflows through the brightenings is found to be ∼10{sup 21} erg. Larger FOV observations from BBSO full-disk H α images show that the AR end of the filament started ascending four hours before the flare. We attribute the observed downflows at the AR end of the filament to the draining effect of the filament rising prior to its eruption. During the slow-rise phase, the downflows continuously drained away ∼10{sup 15}g mass from the filament over a few hours, which is believed to be essential for the instability, and could be an important precursor of eruptive events.« less

Authors:
; ; ;  [1]
  1. Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States)
Publication Date:
OSTI Identifier:
22663554
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 841; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALTITUDE; CHROMOSPHERE; ERUPTION; EVOLUTION; FILAMENTS; IMAGES; INSTABILITY; MAGNETIC FIELDS; MASS; PLASMA; PRECURSOR; RESOLUTION; SUN; SUNSPOTS; TELESCOPES; VELOCITY; VISIBLE RADIATION

Citation Formats

Li, Qin, Deng, Na, Jing, Ju, and Wang, Haimin, E-mail: ql47@njit.edu. High-resolution Observations of Downflows at One End of a Pre-eruption Filament. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6FAA.
Li, Qin, Deng, Na, Jing, Ju, & Wang, Haimin, E-mail: ql47@njit.edu. High-resolution Observations of Downflows at One End of a Pre-eruption Filament. United States. doi:10.3847/1538-4357/AA6FAA.
Li, Qin, Deng, Na, Jing, Ju, and Wang, Haimin, E-mail: ql47@njit.edu. Thu . "High-resolution Observations of Downflows at One End of a Pre-eruption Filament". United States. doi:10.3847/1538-4357/AA6FAA.
@article{osti_22663554,
title = {High-resolution Observations of Downflows at One End of a Pre-eruption Filament},
author = {Li, Qin and Deng, Na and Jing, Ju and Wang, Haimin, E-mail: ql47@njit.edu},
abstractNote = {Studying the dynamics of filaments at the pre-eruption phase can shed light on the precursor of eruptive events. Such high-resolution studies (of the order of 0.″1) are highly desirable yet very rare. In this work, we present a detailed observation of a pre-eruption evolution of a filament obtained by the 1.6 m New Solar Telescope (NST) at the Big Bear Solar Observatory (BBSO). One end of the filament is anchored at the sunspot in the NOAA active region (AR) 11515, which is well observed by NST H α off-bands from four hours before to one hour after the filament eruption. A M1.6 flare is associated with the eruption. We observed persistent downflowing materials along the H α multi-threaded component of the loop toward the AR end during the pre-eruption phase. We traced the trajectories of plasma blobs along the H α threads and obtained a plane-of-sky velocity of 45 km s{sup −1} on average. Furthermore, we estimated the real velocities of the downflows and the altitude of the filament by matching the observed H α threads with magnetic field lines extrapolated from a nonlinear force-free field model. Observations of chromospheric brightenings at the footpoints of the falling plasma blobs are also presented. The lower limit of the kinetic energy per second of the downflows through the brightenings is found to be ∼10{sup 21} erg. Larger FOV observations from BBSO full-disk H α images show that the AR end of the filament started ascending four hours before the flare. We attribute the observed downflows at the AR end of the filament to the draining effect of the filament rising prior to its eruption. During the slow-rise phase, the downflows continuously drained away ∼10{sup 15}g mass from the filament over a few hours, which is believed to be essential for the instability, and could be an important precursor of eruptive events.},
doi = {10.3847/1538-4357/AA6FAA},
journal = {Astrophysical Journal},
number = 2,
volume = 841,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}