54 research outputs found
Observational Study Of the Quasi-Periodic Fast Propagating Magnetosonic Waves and the Associated Flare on 2011 May 30
On 2011 May 30, quasi-periodic fast propagating (QFP) magnetosonic waves
accompanied by a C2.8 flare were directly imaged by the Atomospheric Imaging
Assembly instrument on board the Solar Dynamics Observatory. The QFP waves
successively emanated from the flare kernel, they propagated along a cluster of
open coronal loops with a phase speed of 834 km/s during the flare's rising
phase, and the multiple arc-shaped wave trains can be fitted with a series of
concentric circles. We generate the k-omega diagram of the Fourier power and
find a straight ridge that represents the dispersion relation of the waves.
Along the ridge, we find a lot of prominent nodes which represent the available
frequencies of the QFP waves. On the other hand, the frequencies of the flare
are also obtained by analyzing the flare light curves using the wavelet
technique. The results indicate that almost all the main frequencies of the
flare are consistent with those of the QFP waves. This suggests that the flare
and the QFP waves were possibly excited by a common physical origin. On the
other hand, a few low frequencies revealed by the k-omega diagram can not be
found in the accompanying flare. We propose that these low frequencies were
possibly due to the leakage of the pressure-driven p-mode oscillations from the
photosphere into the low corona, which should be a noticeable mechanism for
driving the QFP waves observed in the corona.Comment: Published in Ap
Simultaneous Observations of a Large-Scale Wave Event in the Solar Atmosphere: From Photosphere to Corona
For the first time, we report a large-scale wave that was observed
simultaneously in the photosphere, chromosphere, transition region and low
corona layers of the solar atmosphere. Using the high temporal and high spatial
resolution observations taken by the Solar Magnetic Activity Research Telescope
at Hida Observatory and the Atmospheric Imaging Assembly (AIA) onboard Solar
Dynamic Observatory, we find that the wave evolved synchronously at different
heights of the solar atmosphere, and it propagated at a speed of 605 km/s and
showed a significant deceleration (-424 m/s2) in the extreme-ultraviolet (EUV)
observations. During the initial stage, the wave speed in the EUV observations
was 1000 km/s, similar to those measured from the AIA 1700 {\AA} (967 km/s) and
1600 {\AA} (893 km/s) observations. The wave was reflected by a remote region
with open fields, and a slower wave-like feature at a speed of 220 km/s was
also identified following the primary fast wave. In addition, a type-II radio
burst was observed to be associated with the wave. We conclude that this wave
should be a fast magnetosonic shock wave, which was firstly driven by the
associated coronal mass ejection and then propagated freely in the corona. As
the shock wave propagated, its legs swept the solar surface and thereby
resulted in the wave signatures observed in the lower layers of the solar
atmosphere. The slower wave-like structure following the primary wave was
probably caused by the reconfiguration of the low coronal magnetic fields, as
predicted in the field-line stretching model.Comment: Published in ApJ
Measuring three-dimensional shapes of stable solar prominences using stereoscopic observations from SDO and STEREO
Although the real shapes and trajectories of erupting solar prominences in
three dimensions have been intensively studied, the three-dimensional (3D)
shapes of stable prominences before eruptions have not been measured accurately
so far. We intend to make such a measurement to constrain 3D prominence models
and to extend our knowledge of prominences. Using multiperspective observations
from the Atmospheric Imaging Assembly on board SDO and the Extreme Ultraviolet
Imager on board STEREO, we reconstructed 3D coordinates of three stable
prominences: a quiescent, an intermediate, and a mixed type. Based on the 3D
coordinates, we measured the height, length, and inclination angle of the legs
of these prominences. To study the spatial relationship between the footpoints
of prominences and photospheric magnetic structures, we also used the Global
Oscillation Network Group H alpha images and magnetograms from the HMI on board
the SDO. In three stable prominences, we find that the axes of the prominence
legs are inclined by 68 degrees on average to the solar surface. Legs at
different locations along a prominence axis have different heights with a two-
to threefold difference. Our investigation suggests that over 96% of prominence
footpoints in a sample of 70 footpoints are located at supergranular
boundaries. The widths of two legs have similar values measured in two
orthogonal lines of sight. We also find that a prominence leg above the solar
limb showed horizontal oscillations with larger amplitudes at higher locations.
With a limited image resolution and number of cases, our measurement suggests
that the legs of prominences may have various orientations and do not always
stand vertically on the surface of the sun. Moreover, the locations of
prominence legs are closely related to supergranules.Comment: 11 figure
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