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Spatial and temporal analysis of 3-minute oscillations in the chromosphere associated with the X2.2 Solar Flare on 2011 February 15  

James McAteer   Submitted: 2021-02-17 10:19

3-minute oscillations in the chromosphere are attributed to both slow magnetoacoustic waves propagating from the photosphere, and to oscillations generated within the chromosphere itself at its natural frequency as a response to a disturbance. Here we present an investigation of the spatial and temporal behavior of the chromospheric 3-minute oscillations before, during, and after the SOL2011-02-15T01:56 X2.2 flare. Observations in ultraviolet emission centered on 1600 and 1700 Angstroms obtained at 24- second cadence from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory are used to create power maps as functions of both space and time. We observe higher 3-minute power during the flare, spatially concentrated in small areas 10 pixels (4 arcseconds) across. This implies that the chromospheric plasma is not oscillating globally as a single body. The locations of increased 3-minute power are consistent with observations of HXR flare emission from previous studies, suggesting that these small areas are manifestations of the chromosphere responding to injection of energy by nonthermal particles. This supports the theory that the chromosphere oscillates at the acoustic cutoff frequency in response to a disturbance.

Authors: Farris, L., McAteer, R.T.J.
Projects: SDO-AIA,SDO-HMI

Publication Status: Published
Last Modified: 2021-02-17 22:42
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Magnetic Structure of an Erupting Filament  

James McAteer   Submitted: 2020-04-10 10:03

The full 3-D vector magnetic field of a solar filament prior to eruption is presented. The filament was observed with the Facility Infrared Spectropolarimeter at the Dunn Solar Telescope in the chromospheric He i line at 10830 on May 29 and 30, 2017. We inverted the spectropolarimetric observations with the HAnle and ZEeman Light (HAZEL) code to obtain the chromospheric magnetic field. A bimodal distribution of field strength was found in or near the filament. The average field strength was 24 Gauss, but prior to the eruption we find the 90th percentile of field strength was 435 Gauss for the observations on May 29. The field inclination was about 67 degree from the solar vertical. The field azimuth made an angle of about 47 to 65 degree to the spine axis. The results suggest an inverse configuration indicative of a flux rope topology. He i intensity threads were found to be co-aligned with the magnetic field direction. The filament had a sinistral configuration as expected for the southern hemisphere. The filament was stable on May 29, 2017 and started to rise during two observations on May 30, before erupting and causing a minor coronal mass ejection. There was no obvious change of the magnetic topology during the eruption process. Such information on the magnetic topology of erupting filaments could improve the prediction of the geoeffectiveness of solar storms.

Authors: Shuo Wang, Jack M. Jenkins, Valentin Martinez Pillet, Christian Beck, David M. Long, Debi Prasad Choudhary, Karin Muglach, James McAteer
Projects: DST/IBIS

Publication Status: Published
Last Modified: 2020-04-10 20:02
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On the non-Kolmogorov nature of flare-productive solar active regions  

James McAteer   Submitted: 2016-11-16 12:42

A magnetic power spectral analysis is performed on 53 solar active regions, observed from August 2011 to July 2012. Magnetic field data obtained from the Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used to study the evolution of the magnetic power index as each region rotates across the solar disk. Active regions are classified based on the number, and sizes, of solar flares they produce, in order to study the relationship between flare productivity and the magnetic power index. The choice of window size and inertial range plays a key role in determining the correct magnetic power index. The overall distribution of magnetic power indices has a range of 1.0-2.5. Flare-quiet regions peak at a value of 1.6, however flare-productive regions peak at a value of 2.2. Overall, the histogram of the distribution of power indices of flare-productive active regions is well separated from flare-quiet active regions. Only 12% of flare-quiet regions exhibit an index greater than 2, whereas 90% of flare-productive regions exhibit an index greater than 2. Flare-quiet regions exhibit a high temporal variance (i.e, the index fluctuates between high and low values), whereas flare-productive regions maintain an index greater than 2 for several days. This shows the importance of including the temporal evolution of active regions in flare prediction studies, and highlights the potential of a 2-3 day prediction window for space weather applications.

Authors: Mandage, R.S., McAteer, R.T.J.
Projects: SDO-HMI

Publication Status: Accepted
Last Modified: 2016-11-16 12:57
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Abstracts by Author
Spatial and temporal analysis of 3-minute oscillations in the chromosphere associated with the X2.2 Solar Flare on 2011 February 15
Magnetic Structure of an Erupting Filament
On the non-Kolmogorov nature of flare-productive solar active regions

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