Search Publications
Coronal Transient Events During Two Solar Minima: Their Solar Source Regions and Interplanetary Counterparts
Mandrini, C. H.; Dasso, S.; Cremades, H.
In the frame of two coordinated observational and research efforts, two full solar rotations were investigated in the times of two distinct solar minima. These two campaigns were dubbed Whole Sun Month (WSM; 10 August - 8 September 1996) and Whole Heliosphere Interval (WHI; 20 March - 16 April 2008). The nearly uninterrupted gathering of solar cor…
Determining the Solar Source of a Magnetic Cloud Using a Velocity Difference Technique
Mandrini, C. H.; Gulisano, A. M.; Dasso, S. +3 more
For large eruptions on the Sun, it is often a problem that the core dimming region cannot be observed due to the bright emission from the flare itself. However, spectroscopic data can provide the missing information through the measurement of Doppler velocities. In this paper we analyse the well-studied flare and coronal mass ejection that erupted…
Probing the Role of Magnetic-Field Variations in NOAA AR 8038 in Producing a Solar Flare and CME on 12 May 1997
Jain, Rajmal; Bharti, Lokesh; Hanaoka, Y. +3 more
We carried out a multi-wavelength study of a Coronal Mass Ejection (CME) and an associated flare, occurring on 12 May 1997. We present a detailed investigation of magnetic-field variations in NOAA Active Region 8038 which was observed on the Sun during 7 - 16 May 1997. This region was quiet and decaying and produced only a very small flare activit…
Energy-Dependent Timing of Thermal Emission in Solar Flares
Awasthi, Arun Kumar; Aschwanden, Markus J.; Jain, Rajmal +1 more
We report solar flare plasma to be multi-thermal in nature based on the theoretical model and study of the energy-dependent timing of thermal emission in ten M-class flares. We employ high-resolution X-ray spectra observed by the Si detector of the "Solar X-ray Spectrometer" (SOXS). The SOXS onboard the Indian GSAT-2 spacecraft was launched by the…
The Correlation between the Magnetic and Velocity Fields on the Full Solar Disk
Zhang, H. Q.; Zhao, M. Y.; Wang, X. F.
A possible correlation between the magnetic and velocity fields has been analyzed based on the SOHO/MDI magnetograms and Dopplergrams. It is found that the observed large-scale weak magnetic field (weaker than 50 G (gauss)) is correlated with the velocity statistically. The curves of u⋅b with latitude, where u and b are the velocity and magnetic f…
"Hare and Hounds" Tests of Helioseismic Holography
Kosovichev, A. G.; Birch, A. C.; Braun, D. C. +1 more
We use the output of numerical wave-propagation simulations as synthetic data for "hare and hounds" tests of helioseismic holography. In the simple non-magnetic models examined here, we show that when the inversion method includes a consistent treatment of the filtering applied during the data analysis the inversions for the subsurface sound speed…
Quadrupolar Dimmings During a Partial Halo Coronal Mass Ejection Event
Yang, L.; Hong, J.; Yang, J. +3 more
We present detailed observations of the formations of four distinct coronal dimmings during a flare of 17 September 2002, which was followed by an eruption of a huge coronal loop system, and then an over-and-out partial halo coronal mass ejection (CME), with the same direction as the loop system eruption but laterally far offset from the flare sit…
Speed Distributions of Merging X-Ray Sources During Chromospheric Evaporation in Solar Flares
Ning, Zongjun
We explore the speed distributions of X-ray source motions after the start of chromospheric evaporation in two Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) flares. First, we make CLEAN images at 15 energy bands with a 12 second integration window; then, we outline a flaring loop geometry to cover the looptop and footpoint sources …
Hard X-ray Source Distributions on EUV Bright Kernels in a Solar Flare
Cao, Wenda; Ning, Zongjun
We explore the hard X-ray source distributions of an C1.1 flare occurred on 14 December 2007. Both Hinode/EIS and RHESSI observations are used. One of EIS rasters perfectly covers the double hard X-ray footpoints, where the EUV emission appears strong from the cool line of He II (log T=4.7) to the hot line of Fe XVI (log T=6.4). We analyze RHESSI …
Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots
Zhao, Junwei; Ilonidis, Stathis
The power of solar acoustic waves is reduced inside sunspots mainly due to absorption, emissivity reduction, and local suppression. The coefficients of these power-reduction mechanisms can be determined by comparing time - distance cross-covariances obtained from sunspots and from the quiet Sun. By analyzing 47 active regions observed by SOHO/MDI …