Search Publications
Radio Emission of the Quiet Sun and Active Regions (Invited Review)
Shibasaki, K.; Alissandrakis, C. E.; Pohjolainen, S.
Solar radio emission provides valuable information on the structure and dynamics of the solar atmosphere above the temperature minimum. We review the background and most recent observational and theoretical results on the quiet Sun and active region studies, covering the entire radio range from millimeter to decameter wavelengths. We examine small…
Small-Scale Flux Emergence Observed Using Hinode/SOT
Parnell, C. E.; Thornton, L. M.
The aim of this paper is to determine the flux emergence rate due to small-scale magnetic features in the quiet Sun using high-resolution Hinode SOT NFI data. Small-scale magnetic features are identified in the data using two different feature identification methods (clumping and downhill); then three methods are applied to detect flux emergence e…
Homologous Flares and Magnetic Field Topology in Active Region NOAA 10501 on 20 November 2003
Mandrini, C. H.; Schmieder, B.; Démoulin, P. +4 more
We present and interpret observations of two morphologically homologous flares that occurred in active region (AR) NOAA 10501 on 20 November 2003. Both flares displayed four homologous Hα ribbons and were both accompanied by coronal mass ejections (CMEs). The central flare ribbons were located at the site of an emerging bipole in the centre of the…
Coronal-Temperature-Diagnostic Capability of the Hinode/ X-Ray Telescope Based on Self-Consistent Calibration
Weber, M.; Golub, L.; Bando, T. +10 more
The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray imager that observes the solar corona with unprecedentedly high angular resolution (consistent with its 1″ pixel size). XRT has nine X-ray analysis filters with different temperature responses. One of the most significant scientific features of this telescope is its capability of d…
Coronal Shock Waves, EUV Waves, and Their Relation to CMEs. I. Reconciliation of "EIT Waves", Type II Radio Bursts, and Leading Edges of CMEs
Grechnev, V. V.; Chertok, I. M.; Uralov, A. M. +5 more
We show examples of the excitation of coronal waves by flare-related abrupt eruptions of magnetic rope structures. The waves presumably rapidly steepened into shocks and freely propagated afterwards like decelerating blast waves that showed up as Moreton waves and EUV waves. We propose a simple quantitative description for such shock waves to reco…
Comparison of Observations at ACE and Ulysses with Enlil Model Results: Stream Interaction Regions During Carrington Rotations 2016 - 2018
Luhmann, J. G.; Russell, C. T.; Jian, L. K. +6 more
During the latitudinal alignment in 2004, ACE and Ulysses encountered two stream interaction regions (SIRs) each Carrington rotation from 2016 to 2018, at 1 and 5.4 AU, respectively. More SIR-driven shocks were observed at 5.4 AU than at 1 AU. Three small SIRs at 1 AU merged to form a strong SIR at 5.4 AU. We compare the Enlil model results with s…
Statistical Comparison of Magnetic Clouds with Interplanetary Coronal Mass Ejections for Solar Cycle 23
Lepping, R. P.; Wu, Chin-Chun
We compare the number and characteristics of interplanetary coronal mass ejections (ICMEs) to those of magnetic clouds (MCs) by using in-situ solar wind plasma and magnetic field observations made at 1 AU during solar cycle 23. We found that ≈ 28% of ICMEs appear to contain MCs, since 103 magnetic clouds (MCs) occurred during 1995 - 2006, and 307 …
The Whole Heliosphere Interval in the Context of a Long and Structured Solar Minimum: An Overview from Sun to Earth
Thompson, B. J.; de Toma, G.; Riley, P. +9 more
Throughout months of extremely low solar activity during the recent extended solar-cycle minimum, structural evolution continued to be observed from the Sun through the solar wind and to the Earth. In 2008, the presence of long-lived and large low-latitude coronal holes meant that geospace was periodically impacted by high-speed streams, even thou…
Some Characteristics of the Ionospheric Behavior During the Solar Cycle 23 - 24 Minimum
Araujo-Pradere, Eduardo A.; Redmon, Rob; Fedrizzi, Mariangel +2 more
The Solar Cycle 23 - 24 minimum has been considered unusually deep and complex. In this article we study the ionospheric behavior during this minimum, and we have found that, although observable, the ionosphere response is minor and marginally exceeds the range of normal geophysical variability of the system. Two main ionospheric parameters have b…
Coronal Shock Waves, EUV Waves, and Their Relation to CMEs. III. Shock-Associated CME/EUV Wave in an Event with a Two-Component EUV Transient
Eselevich, M. V.; Eselevich, V. G.; Grechnev, V. V. +5 more
On 17 January 2010, STEREO-B observed in extreme ultraviolet (EUV) and white light a large-scale dome-shaped expanding coronal transient with perfectly connected off-limb and on-disk signatures. Veronig et al. (Astrophys. J. Lett.716, L57, 2010) concluded that the dome was formed by a weak shock wave. We have revealed two EUV components, one of wh…