Search Publications
Statistical Study of Network Jets Observed in the Solar Transition Region: a Comparison Between Coronal Holes and Quiet-Sun Regions
Cranmer, Steven R.; Tian, Hui; Banerjee, Dipankar +4 more
Recent IRIS observations have revealed a prevalence of intermittent small-scale jets with apparent speeds of 80 -250 kms−1, emanating from small-scale bright regions inside network boundaries of coronal holes. We find that these network jets appear not only in coronal holes but also in quiet-sun regions. Using IRIS 1330 Å (C II) slit-ja…
A Study of Heliospheric Modulation and Periodicities of Galactic Cosmic Rays During Cycle 24
Moon, Y. -J.; Chowdhury, Partha; Kudela, K.
Galactic cosmic rays (GCRs) are energetic, charged particles coming from outside the solar system. These particles encounter an outward-moving turbulent solar wind with cyclic magnetic-field fluctuations when entering the heliosphere. This causes convection and diffusion in the heliosphere. The GCR counts detected by the ground-based neutron-monit…
Annual Cosmic Ray Spectra from 250 MeV up to 1.6 GeV from 1995 - 2014 Measured with the Electron Proton Helium Instrument onboard SOHO
Gómez-Herrero, R.; Heber, B.; Kühl, P.
The solar modulation of galactic cosmic rays (GCR) can be studied in detail by examining long-term variations of the GCR energy spectrum (e.g. on the scales of a solar cycle). With almost 20 years of data, the Electron Proton Helium INstrument (EPHIN) onboard the SOlar and Heliospheric Observatory (SOHO) is well suited for this kind of investigati…
Spatio-temporal Dynamics of Sources of Hard X-Ray Pulsations in Solar Flares
Zimovets, I. V.; Struminsky, A. B.; Kuznetsov, S. A. +1 more
We present a systematic analysis of the spatio-temporal evolution of sources of hard X-ray (HXR) pulsations in solar flares. We concentrate on disk flares whose impulsive phases are accompanied by a series of more than three successive peaks (pulsations) of HXR emission detected in the RHESSI 50 - 100 keV energy channel with a four-second time cad…
Coronal Hole and Solar Global Magnetic Field Evolution in 1976 - 2012
Bilenko, Irina A.; Tavastsherna, Ksenia S.
We study the spatial-temporal evolution of a coronal hole and compare it with that of the solar global magnetic field in Cycles 21 - 23 (1976 - 2012). We also analyze the latitude-longitude distribution dynamics of coronal holes and the regularities in the global magnetic field associated with the solar polar field reversal. Polar and non-polar co…
A Tiny Eruptive Filament as a Flux-Rope Progenitor and Driver of a Large-Scale CME and Wave
Grechnev, V. V.; Fainshtein, V. G.; Kochanov, A. A. +5 more
A solar eruptive event SOL2010-06-13 observed with the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) has been extensively discussed in the contexts of the CME development and an associated extreme-ultraviolet (EUV) wave-like transient in terms of a shock driven by the apparent CME rim. Continuing the analysis of this e…
A Comparison of Global Magnetic Field Skeletons and Active-Region Upflows
Culhane, J. L.; Brooks, D. H.; Harra, L. K. +2 more
Plasma upflows have been detected in active regions using Doppler velocity maps. The origin and nature of these upflows is not well known with many of their characteristics determined from the examination of single events. In particular, some studies suggest these upflows occur along open field lines and, hence, are linked to sources of the solar …
Sources of the Slow Solar Wind During the Solar Cycle 23/24 Minimum
Madjarska, M. S.; Kilpua, E. K. J.; Wiegelmann, T. +4 more
We investigate the characteristics and the sources of the slow (<450 kms−1) solar wind during the four years (2006 - 2009) of low solar activity between Solar Cycles 23 and 24. We used a comprehensive set of in-situ observations in the near-Earth solar wind (Wind and ACE) and removed the periods when large-scale interplanetary corona…
Two Exceptions in the Large SEP Events of Solar Cycles 23 and 24
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +3 more
We discuss our findings from a survey of all large solar energetic particle (SEP) events of Solar Cycles 23 and 24, i.e. the SEP events where the intensity of > 10 MeV protons observed by GOES was > 10 pfu. In our previous work (Gopalswamy et al. in Geophys. Res. Lett. 41, 2673, 2014) we suggested that ground level enhancements (GLEs) in Cyc…
Properties of Magnetic Tongues over a Solar Cycle
Démoulin, Pascal; Mandrini, Cristina H.; López Fuentes, Marcelo +1 more
The photospheric spatial distribution of the main magnetic polarities of bipolar active regions (ARs) present during their emergence deformations are known as magnetic tongues. They are attributed to the presence of twist in the toroidal magnetic-flux tubes that form the ARs. The aim of this article is to study the twist of newly emerged ARs from …