CORONAL LOOP OSCILLATIONS OBSERVED WITH ATMOSPHERIC IMAGING ASSEMBLY—KINK MODE WITH CROSS-SECTIONAL AND DENSITY OSCILLATIONS

By Markus J. Aschwanden, C. Schrijver. 2011

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A detailed analysis of a coronal loop oscillation event is presented, using data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO) for the first time. The loop oscillation event occurred on 2010 October 16, 19:05–19:35 UT and was triggered by an M2.9 GOES-class flare, located inside a highly inclined cone of a narrow-angle coronal mass ejection. This oscillation event had a number of unusual features: (1) excitation of kink-mode oscillations in vertical polarization (in the loop plane), (2) coupled cross-sectional and density oscillations with identical periods, (3) no detectable kink amplitude damping over the observed duration of four kink-mode periods (P=6.3 minutes), (4) multi-loop oscillations with slightly (≈10%) different periods, and (5) a relatively cool loop temperature of T ≈ 0.5 MK. We employ a novel method of deriving the electron density ratio external and internal to the oscillating loop from the ratio of Alfvénic speeds deduced from the flare trigger delay and the kink-mode period, i.e., ne/ni = (vA/vAe)2 = 0.08 ± 0.01. The coupling of the kink mode and cross-sectional oscillations can be explained as a consequence of the loop length variation in the vertical polarization mode. We determine the exact footpoint locations and loop length with stereoscopic triangulation using STEREO/EUVI/A data. We model the magnetic field in the oscillating loop using Helioseismic and Magnetic Imager/SDO magnetogram data and a potential-field model and find agreement with the seismological value of the magnetic field, Bkink = 4.0 ± 0.7 G, within a factor of two.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/a87d48f01ad457ad4d611e6cca1465b7e878528f

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Citations in the corpus

EVOLUTION OF MAGNETIC FIELD AND ENERGY IN A MAJOR ERUPTIVE ACTIVE REGION BASED ON SDO/HMI OBSERVATION (2011, background): “Detailed analysis of EUV loop motion may provide quantitative diagnostics of the coronal field (e.g Aschwanden & Schrijver 2011), but is out of the scope of this work.”
Advances in Observing Various Coronal EUV Waves in the SDO Era and Their Seismological Applications (Invited Review) (2014, unknown): “…reviews (Aschwanden, 2004; Nakariakov and Verwichte, 2005; Banerjee et al., 2007; Roberts, 2008; Ofman, 2009) and recent AIA observations (e.g. Aschwanden and Schrijver, 2011; McIntosh et al., 2011; Wang et al., 2012; Gosain and Foullon, 2012; White and Verwichte, 2012; Srivastava and…”
Decayless low-amplitude kink oscillations: a common phenomenon in the solar corona? (2015, background): “Kink waves ar observed as standing (e.g. Aschwanden et al. 1999; Nakariakov et al. 1999; Aschwanden & Schrijver 2011) and propagating (e.g. Williams et al. 2001; Tomczyk et al. 2007; Cirtain et al. 2007) disturbances, with the periods ranging from several seconds to several minutes.”