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A Statistical Analysis of Loop-Top Motion in Solar Limb FlaresPrevious studies of hot, thermal solar flare loops imaged with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) have identified several flares for which the loop top shrinks downward early in the impulsive phase and then expands upward later in the impulsive phase (Sui & Holman 2003; Sui, Holman & Dennis 2004; Veronig et al. 2005). This early downward motion is not predicted by flare models. We study a statistical sample of RHESSI flares to assess how common this evolution is and to better characterize it. In a sample of 88 flares near the solar lin$ that show identifiable loop structure in RHESSI images, 66% (58 flares) showed downward loop-top motion followed by upward motion. We therefore conclude that the early downward motion is a frequent characteristic of flare loops. We obtain the distribution of the timing of the change from downward to upward motion relative to flare start and peak times. We also obtain the distributions of downward and upward speeds.
Document ID
20060013150
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Holman, Gordon D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sui, Linhui
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Brosius, D. G.
(Catholic Univ. of America Washington, DC, United States)
Dennis, Brian R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2005
Subject Category
Solar Physics
Meeting Information
Meeting: American Geophysical Union
Location: San Francisco, CA
Country: United States
Start Date: December 5, 2005
End Date: December 8, 2005
Distribution Limits
Public
Copyright
Other

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