QUASI-PERIODIC OSCILLATIONS IN LASCO CORONAL MASS EJECTION SPEEDS
- Department of Physics, Arul Anandar College, Karumathur-625 514 (India)
- School of Space Research, Kyung Hee University, Yongin 446-701 (Korea, Republic of)
- Korea Astronomy and Space Science Institute (KASI), Whaamdong, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of)
- NASA Goddard Space Flight Center, Greenbelt, MD (United States)
- School of Physics, Madurai Kamaraj University, Madurai (India)
- Hvar Observatory, Faculty of Geodesy, Zagreb (Croatia)
Quasi-periodic oscillations in the speed profile of coronal mass ejections (CMEs) in the radial distance range 2-30 solar radii are studied. We considered the height-time data of the 307 CMEs recorded by the Large Angle and Spectrometric Coronagraph (LASCO) during 2005 January-March. In order to study the speed-distance profile of the CMEs, we have used only 116 events for which there are at least 10 height-time measurements made in the LASCO field of view. The instantaneous CME speed is estimated using a pair of height-time data points, providing the speed-distance profile. We found quasi-periodic patterns in at least 15 speed-distance profiles, where the speed amplitudes are larger than the speed errors. For these events we have determined the speed amplitude and period of oscillations. The periods of quasi-periodic oscillations are found in the range 48-240 minutes, tending to increase with height. The oscillations have similar properties as those reported by Krall et al., who interpreted them in terms of the flux-rope model. The nature of forces responsible for the motion of CMEs and their oscillations are discussed.
- OSTI ID:
- 21392475
- Journal Information:
- Astrophysical Journal, Vol. 708, Issue 1; Other Information: DOI: 10.1088/0004-637X/708/1/450; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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