Search Publications
Statistical Analysis of Periodic Oscillations in LASCO Coronal Mass Ejection Speeds
Shanmugaraju, A.; Gopalswamy, N.; Michalek, G. +2 more
A large set of coronal mass ejections (CMEs, 3463) has been selected to study their periodic oscillations in speed in the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) field of view. These events, reported in the SOHO/LASCO catalog in the period of time 1996 - 2004, were selected based on hav…
Evidence of Energy Supply by Active-Region Spicules to the Solar Atmosphere
Ahangarzadeh Maralani, A. R.; Tavabi, E.; Ajabshirizadeh, A. +1 more
We investigate the role of active-region spicules in the mass balance of the solar wind and energy supply in heating the solar atmosphere. We use high-cadence observations from the Solar Optical Telescope (SOT) onboard the Hinode satellite in the Ca II H-line filter obtained on 26 January 2007. The observational technique provides the high spatio-…
The Broken Lane of a Type II Radio Burst Caused by Collision of a Coronal Shock with a Flare Current Sheet
Lin, Jun; Wang, Min; Gao, Guannan +3 more
We investigated a peculiar metric type II solar radio burst with a broken lane structure that was observed on November 13, 2012. In addition to the radio data, we also studied the data in other wavelengths. The bursts were associated with two coronal mass ejections (CMEs) and two flares that originated from Active Region AR 11613. A long current s…
Neutral Hydrogen and Its Emission Lines in the Solar Corona
Vial, Jean-Claude; Chane-Yook, Martine
Since the Lyman-α rocket observations of Gabriel (Solar Phys.21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coron…
Angular Dependence of the Facular-Sunspot Coverage Relation as Derived by MDI Magnetograms
Criscuoli, S.
Previous studies have shown that the variation over the solar magnetic activity cycle of the area of facular/network features identified from broad-band and narrow-band imagery is positively correlated with the sunspot area and number, the relation being described as either linear or quadratic. On the other hand, the temporal variation of the spat…
Diagnosing the Source Region of a Solar Burst on 26 September 2011 by Using Microwave Type-III Pairs
Huang, J.; Yan, Y.; Karlický, M. +4 more
We report a peculiar and interesting train of microwave Type-III pair bursts in the impulsive rising phase of a solar flare on 26 September 2011. The observations include radio spectrometers at frequencies of 0.80 - 2.00 GHz from the Ondřejov radiospectrograph in the Czech Republic (ORSC), hard X-ray from the Ramaty High-Energy Solar Spectroscopic…
Acoustic and Slow Sausage Oscillations in the Stratified Solar Photosphere: Hinode Observations and Phase Relationships
Tsap, Y. T.; Stepanov, A. V.; Kopylova, Y. G.
Based on the linearized magnetohydrodynamic (MHD) equations within the framework of the thin flux tube approximation, the phase relationships between the disturbed quantities of evanescent acoustic and slow sausage MHD modes excited in the adiabatically stratified solar atmosphere are considered. It has been shown that the sign of the phase differ…
The 26 December 2001 Solar Event Responsible for GLE63. I. Observations of a Major Long-Duration Flare with the Siberian Solar Radio Telescope
Grechnev, V. V.; Kochanov, A. A.
Ground level enhancements (GLEs) of cosmic-ray intensity occur, on average, once a year. Because they are rare, studying the solar sources of GLEs is especially important to approach understanding their origin. The SOL2001-12-26 eruptive-flare event responsible for GLE63 seems to be challenging in some aspects. Deficient observations limited our u…
Deriving Potential Coronal Magnetic Fields from Vector Magnetograms
Welsch, Brian T.; Fisher, George H.
The minimum-energy configuration for the magnetic field above the solar photosphere is curl-free (hence, by Ampère's law, also current-free), so can be represented as the gradient of a scalar potential. Since magnetic fields are divergence free, this scalar potential obeys Laplace's equation, given an appropriate boundary condition (BC). With meas…
Sounding Rocket Observations of Active Region Soft X-Ray Spectra Between 0.5 and 2.5 nm Using a Modified SDO/EVE Instrument
Didkovsky, Leonid; Wieman, Seth; Moore, Christopher +2 more
Spectrally resolved measurements of individual solar active regions (ARs) in the soft X-ray (SXR) range are important for studying dynamic processes in the solar corona and their associated effects on the Earth's upper atmosphere. They are also a means of evaluating atomic data and elemental abundances used in physics-based solar spectral models. …