12 research outputs found
Is the Polar Region Different from the Quiet Region of the Sun?
Observations of the polar region of the Sun are critically important for
understanding the solar dynamo and the acceleration of solar wind. We carried
out precise magnetic observations on both the North polar region and the quiet
Sun at the East limb with the Spectro-Polarimeter of the Solar Optical
Telescope aboard Hinode to characterize the polar region with respect to the
quiet Sun. The average area and the total magnetic flux of the kG magnetic
concentrations in the polar region appear to be larger than those of the quiet
Sun. The magnetic field vectors classified as vertical in the quiet Sun have
symmetric histograms around zero in the strengths, showing balanced positive
and negative flux, while the histogram in the North polar region is clearly
asymmetric, showing a predominance of the negative polarity. The total magnetic
flux of the polar region is larger than that of the quiet Sun. In contrast, the
histogram of the horizontal magnetic fields is exactly the same between the
polar region and the quiet Sun. This is consistent with the idea that a local
dynamo process is responsible for the horizontal magnetic fields. A
high-resolution potential field extrapolation shows that the majority of
magnetic field lines from the kG-patches in the polar region are open with a
fanning-out structure very low in the atmosphere, while in the quiet Sun,
almost all the field lines are closed.Comment: Accepted for publication in AP
Evolution of Anemone AR NOAA 10798 and the Related Geo-Effective Flares and CMEs
We present a detailed examination of the features of the Active Region (AR)
NOAA 10798. This AR generated coronal mass ejections (CMEs) that caused a large
geomagnetic storm on 24 August 2005 with the minimum Dst index of -216 nT. We
examined the evolution of the AR and the features on/near the solar surface and
in the interplanetary space. The AR emerged in the middle of a small coronal
hole, and formed a {\it sea anemone} like configuration. H filaments
were formed in the AR, which have southward axial field. Three M-class flares
were generated, and the first two that occurred on 22 August 2005 were followed
by Halo-type CMEs. The speeds of the CMEs were fast, and recorded about 1200
and 2400 km s, respectively. The second CME was especially fast, and
caught up and interacted with the first (slower) CME during their travelings
toward Earth. These acted synergically to generate an interplanetary
disturbance with strong southward magnetic field of about -50 nT, which was
followed by the large geomagnetic storm.Comment: 32 pages, 9 figures, JGR accepte
Observation results by the TAMA300 detector on gravitational wave bursts from stellar-core collapses
We present data-analysis schemes and results of observations with the TAMA300
gravitational-wave detector, targeting burst signals from stellar-core collapse
events. In analyses for burst gravitational waves, the detection and
fake-reduction schemes are different from well-investigated ones for a
chirp-wave analysis, because precise waveform templates are not available. We
used an excess-power filter for the extraction of gravitational-wave
candidates, and developed two methods for the reduction of fake events caused
by non-stationary noises of the detector. These analysis schemes were applied
to real data from the TAMA300 interferometric gravitational wave detector. As a
result, fake events were reduced by a factor of about 1000 in the best cases.
The resultant event candidates were interpreted from an astronomical viewpoint.
We set an upper limit of 2.2x10^3 events/sec on the burst gravitational-wave
event rate in our Galaxy with a confidence level of 90%. This work sets a
milestone and prospects on the search for burst gravitational waves, by
establishing an analysis scheme for the observation data from an
interferometric gravitational wave detector
High Spatial Resolution imaging for the Nobeyama Radioheliograph and Observations of Weak Activities Prior to Solar Flares
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Magnetohydrodynamic simulation of coronal mass ejections using interplanetary scintillation data observed from radio sites ISEE and LOFAR
Forecasting Heliospheric CME Solar-Wind Parameters Using the UCSD Time-Dependent Tomography and ISEE Interplanetary Scintillation Data: The 10 March 2022 CME
International audienceRemotely sensed interplanetary scintillation (IPS) data from the Institute for Space-Earth Environmental Research (ISEE), Japan, allows a determination of solar-wind parameters throughout the inner heliosphere. We show the 3D analysis technique developed for these data sets that forecast plasma velocity, density, and component magnetic fields at Earth, as well at the other inner heliospheric planets and spacecraft. One excellent coronal mass ejection (CME) example that occurred on the 10 March 2022 was viewed not only in the ISEE IPS analyses, but also by the spacecraft near Earth that measured the CME arrival at one AU. Solar Orbiter, that was nearly aligned along the Earth radial at 0.45 AU, also measured the CME in plasma density, velocity, and magnetic field. BepiColombo at 0.42 AU was also aligned with the STEREO A spacecraft, and viewed this CME. The instruments used here from BepiColombo include: 1) the European-Space-Agency Mercury-Planetary-Orbiter magnetic field measurements; 2) the Japan Aerospace Exploration Agency Mio spacecraft Solar Particle Monitor that viewed the CME Forbush decrease, and the Mercury Plasma Experiment/Mercury Electron Analyzer instruments that measured particles and solar-wind density from below the spacecraft protective sunshield covering. This article summarizes the analysis using ISEE, Japan real-time data for these forecasts: it provides a synopsis of the results and confirmation of the CME event morphology after its arrival, and discusses how future IPS analyses can augment these results