Search Publications
Solar energetic particle access to distant longitudes through turbulent field-line meandering
Laitinen, T.; Dalla, S.; Kopp, A. +2 more
Context. Current solar energetic particle (SEP) propagation models describe the effects of interplanetary plasma turbulence on SEPs as diffusion, using a Fokker-Planck (FP) equation. However, FP models cannot explain the observed fast access of SEPs across the average magnetic field to regions that are widely separated in longitude within the heli…
The injection of ten electron/3He-rich SEP events
Krucker, Säm; Li, Gang; Mason, Glenn M. +2 more
We have derived the particle injections at the Sun for ten good electron/3He-rich solar energetic particle (SEP) events, using a 1.2 AU particle path length (suggested by analysis of the velocity dispersion). The inferred solar injections of high-energy (~10 to 300 keV) electrons and of ~MeV/nucleon ions (carbon and heavier) start with …
Reconstruction of spectral solar irradiance since 1700 from simulated magnetograms
Solanki, S. K.; Yeo, K. L.; Krivova, N. A. +3 more
Aims: We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. This model uses as input magnetograms simulated with a surface flux transport model fed with semi-synthetic records of emerging sunspot groups.
Methods: T…
Photospheric and coronal magnetic fields in six magnetographs. I. Consistent evolution of the bashful ballerina
Mursula, Kalevi; Virtanen, Ilpo
Aims: We study the long-term evolution of photospheric and coronal magnetic fields and the heliospheric current sheet (HCS), especially its north-south asymmetry. Special attention is paid to the reliability of the six data sets used in this study and to the consistency of the results based on these data sets.
Methods: We use synoptic ma…
Conditions for electron-cyclotron maser emission in the solar corona
Bloomfield, D. S.; Zucca, P.; Gallagher, P. T. +1 more
Context. The Sun is an active source of radio emission ranging from long duration radio bursts associated with solar flares and coronal mass ejections to more complex, short duration radio bursts such as solar S bursts, radio spikes and fibre bursts. While plasma emission is thought to be the dominant emission mechanism for most radio bursts, the …
Hot prominence detected in the core of a coronal mass ejection: Analysis of SOHO/UVCS Lα and SOHO/LASCO visible-light observations
Heinzel, P.; Anzer, U.; Jejčič, S. +2 more
Context. The paper deals with the physics of erupting prominences in the core of coronal mass ejections (CME).
Aims: We determine the physical parameters of an erupting prominence embedded in the core of a CME using SOHO/UVCS hydrogen Lα and Lβ lines and SOHO/LASCO visible light observations. In particular we analyze the CME event observed on…
Unexpected spatial intensity distributions and onset timing of solar electron events observed by closely spaced STEREO spacecraft
Gómez-Herrero, R.; Dresing, N.; Heber, B. +2 more
We present multi-spacecraft observations of four solar electron events using measurements from the Solar Electron Proton Telescope (SEPT) and the Electron Proton Helium INstrument (EPHIN) on board the STEREO and SOHO spacecraft, respectively, occurring between 11 October 2013 and 1 August 2014, during the approaching superior conjunction period of…
Coronal mass ejection-related particle acceleration regions during a simple eruptive event
Rouillard, Alexis P.; Klein, Karl-Ludwig; Salas-Matamoros, Carolina
An intriguing feature of many solar energetic particle (SEP) events is the detection of particles over a very extended range of longitudes in the heliosphere. This may be due to peculiarities of the magnetic field in the corona, to a broad accelerator, to cross-field transport of the particles, or to a combination of these processes. The eruptive …
Observations of high and low Fe charge states in individual solar wind streams with coronal-hole origin
Berger, Lars; Heidrich-Meisner, Verena; Wimmer-Schweingruber, Robert +2 more
Context. The solar wind originating from coronal holes is comparatively well-understood and is characterized by lower densities and average charge states compared to the so-called slow solar wind. Except for wave perturbations, the average properties of the coronal-hole solar wind are passably constant.
Aims: In this case study, we focus on o…
Evolution of active region outflows throughout an active region lifetime
Poletto, G.; Zangrilli, L.
Context. We have shown previously that SOHO/UVCS data allow us to detect active region (AR) outflows at coronal altitudes higher than those reached by other instrumentation. These outflows are thought to be a component of the slow solar wind.
Aims: Our purpose is to study the evolution of the outflows in the intermediate corona from AR 8100, …