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J. Jing (BBSO/NJIT), J. Lee (NJIT), T. Spirock, Y. Xu, H. Wang (BBSO/NJIT)
Flow motions observed in and around solar filaments may provide important clues to the study of filament formation and its magnetic field structure. In this paper we report a periodic mass motion within a filament observed using high resolution (1 arcsec) and high cadence (1 min) Halpha camera of the Big Bear Solar Observatory on Oct. 24, 2001. The filament was located above a magnetic neutral line lying between two large bipolar active regions (NOAA 9672 and 9673), which is favorable for formation of a large filament. As an intriguing property, the motion was seemingly triggered by a subflare occurred near one footpoint of the filament and was gradually damped out. This damped oscillation was very clearly seen to traverse a large extent of the filament ~1.4X105 km, and persist over, at least, three complete cycles. In our analysis the period of oscillation is ~79 min and its amplitude initially reaches ~92 km s-1, which decreases at damping timescale ~ 210 min. We briefly discuss various possibilities for explaining this mass motion, to find a remarkable similarity between the present observation and the recent theoretical model in which a constant flow in a filament is driven under thermal non-equilibrium. To follow this idea, it is plausible that the subflare preceding this oscillation provides the local heating needed for driving the motion at sound speed, and that the decay of oscillation is primarily due to radiative damping among other factors. Although this motion is then driven by pressure, presence of a slightly dipped magnetic fields seems still necessary in order to account for the location of the final destination of the motion at the midpoint of the filament.
The author(s) of this abstract have provided an email address for comments about the abstract: jingju@hotmail.com
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.