Search Publications
Radio Pulsating Structures with Coronal Loop Contraction
Pohjolainen, S.; Kallunki, J.
We present a multi-wavelength study of a solar eruption event on 20 July 2004, comprising observations in Hα, EUV, soft X-rays, and in radio waves with a wide frequency range. The analyzed data show both oscillatory patterns and shock wave signatures during the impulsive phase of the flare. At the same time, large-scale EUV loops located above the…
Off-limb (Spicule) DEM Distribution from SoHO/SUMER Observations
Doyle, J. G.; Madjarska, M. S.; Vanninathan, K. +1 more
In the present work we derive a Differential Emission Measure (DEM) distribution from a region dominated by spicules. We use spectral data from the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on-board the Solar Heliospheric Observatory (SoHO) covering the entire SUMER wavelength range taken off-limb in the Northern pol…
Observed Effect of Magnetic Fields on the Propagation of Magnetoacoustic Waves in the Lower Solar Atmosphere
Lawrence, J. K.; Cadavid, A. C.
We study Hinode/SOT-FG observations of intensity fluctuations in Ca II H-line and G-band image sequences and their relation to simultaneous and co-spatial magnetic field measurements. We explore the G-band and H-line intensity oscillation spectra both separately and comparatively via their relative phase differences, time delays and cross-coherenc…
Prominent Photospheric Downflows on Magnetic Neutral Line in a Delta-Type Sunspot
Zhang, Y.; Takizawa, K.; Kitai, R.
It is known that δ-type sunspot groups have a high flare productivity and produce strong flares. In particular, βγδ type sunspots are the most active type of all. A βγδ active region NOAA 9957 with frequent flux cancellations but without any marked flare activity during its decay phase was studied in this work. Using SOHO/MDI Dopplergrams and magn…
Dynamics of CMEs in the LASCO Field of View - Statistical Analysis
Michalek, G.
A large set of CMEs (2207) has been selected to study their dynamics in the SOHO/LASCO field of view (LFOV). These selected events have at least seven height-time measurements and their acceleration can be determined separately in the C2 and C3 LFOVs. It was demonstrated that the balance between the aerodynamic drag and driving Lorentz forces may …
Allen Telescope Array Multi-frequency Observations of the Sun
Hurford, G. J.; Saint-Hilaire, P.; Bower, G. C. +2 more
We present the first observations of the Sun with the Allen Telescope Array (ATA). We used up to six frequencies, from 1.43 to 6 GHz, and baselines from 6 to 300 m. To our knowledge, these are the first simultaneous multi-frequency full-Sun maps obtained at microwave frequencies without mosaicing. The observations took place when the Sun was relat…
The Asymmetrical Eruption of a Quiescent Filament and Associated Halo CME
Li, H.; Hong, J.; Yang, J. +5 more
We will present detailed observations of the asymmetrical eruption of a large quiescent filament on 24 November 2002, which was followed by a two-ribbon flare, three coronal dimmings, endpoint brightenings, and a very fast halo-type coronal mass ejection (CME). Before the eruption, the filament lay along the main neutral line (MNL) underneath a si…
Multiwavelength Observations of Supersonic Plasma Blob Triggered by Reconnection-Generated Velocity Pulse in AR10808
Srivastava, A. K.; Murawski, K.; Erdélyi, R. +1 more
Using multi-wavelength observations of Solar and Heliospheric Observatory (SoHO)/Michelson Doppler Imager (MDI), Transition Region and Coronal Explorer (TRACE, 171 Å), and Hα from Culgoora Solar Observatory at Narrabri, Australia, we present a unique observational signature of a propagating supersonic plasma blob before an M6.2-class solar flare i…
EUV Analysis of a Quasi-static Coronal Loop Structure
McKenzie, D. E.; Martens, P. C. H.; Scott, J. T.
Decaying active region 10942 is investigated from 4:00 - 16:00 UT on 24 February 2007 using a suite of EUV observing instruments. Results from Hinode/EIS, STEREO and TRACE show that, although the active region has decayed and no sunspot is present, the physical mechanisms that produce distinguishable loop structures, spectral line broadening, and …
Acoustic Events in the Solar Atmosphere from Hinode/SOT NFI Observations
Roudier, T.; Rieutord, M.; Malherbe, J. -M. +2 more
We investigate the properties of acoustic events (AEs), defined as spatially concentrated and short duration energy flux, in the quiet Sun, using observations of a 2D field of view (FOV) with high spatial and temporal resolution provided by the Solar Optical Telescope (SOT) onboard Hinode. Line profiles of Fe I 557.6 nm were recorded by the Narrow…