Journal: Solar Physics

Abbreviation

Sol. Phys.

Publisher

Springer

Journal Volumes

ISSN

0038-0938
1573-093X

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Publications1 - 10 of 38
  • Location of Decimetric Pulsations in Solar Flares
    Item type: Journal Article
    Benz, Arnold O.; Battaglia, Marina; Vilmer, Nicole (2011)
    Solar Physics
  • So Far, so Good - My First 82 Years
    Item type: Journal Article
    Stenflo, Jan Olof (2025)
    Solar Physics
    My romantic attraction to the stars started at the age of 11 under the dark Swedish skies. While it was clear from then on that I wanted to be an astronomer, a sequence of chance encounters led me to choose solar physics and embark on an unpredictable path across the globe, including work for my PhD in the USSR about the Sun's magnetic field, followed by an experiment on a Soviet satellite to record scattering polarization on the Sun. On my first hike in the Rocky Mountains in 1971, I had a chance encounter with my future wife and married 4 months later in Sweden. In 1980, we moved to Switzerland for 43 years. Finally, our geographically scattered family reunited. All of us, sons and grandsons, are now settled in Colorado. My story tells how this unplanned path was intertwined with the search for answers about the nature of solar magnetism.
  • Triangulation of Hard X-Ray Sources in an X-Class Solar Flare with ASO-S/HXI and Solar Orbiter/STIX
    Item type: Journal Article
    Ryan, Daniel F.; Massa, Paolo; Battaglia, Andrea F.; et al. (2024)
    Solar Physics
    HXI on ASO-S and STIX onboard Solar Orbiter are the first simultaneously operating solar hard X-ray imaging spectrometers. ASO-S's low Earth orbit and Solar Orbiter's periodic displacement from the Sun-Earth line enables multi-viewpoint solar hard X-ray spectroscopic imaging analysis for the first time. Here, we demonstrate the potential of this new capability by reporting the first results of 3D triangulation of hard X-ray sources in the SOL2023-12-31T21:55 X5 flare. HXI and STIX observed the flare near the east limb with an observer separation angle of 18 degrees. We triangulated the brightest regions within each source, which enabled us to characterise the large-scale hard X-ray geometry of the flare. The footpoints were found to be in the chromosphere within uncertainty, as expected, while the thermal looptop source was centred at an altitude of 15.1 +/- 1 Mm. Given the footpoint separation, this implies a more elongated magnetic-loop structure than predicted by a semi-circular model. These results show the strong diagnostic power of joint HXI and STIX observations for understanding the 3D geometry of solar flares. We conclude by discussing the next steps required to fully exploit their potential.
  • Callisto
    Item type: Journal Article
    Benz, Arnold O.; Monstein, Christian; Meyer, Hansueli (2005)
    Solar Physics
  • Hard X-rays, ejecta, and their associated decimetric radio emission in solar flares
    Item type: Journal Article
    Saint-Hilaire, Pascal; Benz, Arnold O. (2003)
    Solar Physics
  • Observation of an Extraordinary Type V Solar Radio Burst: Nonlinear Evolution of the Electron Two-Stream Instability
    Item type: Journal Article
    Benz, Arnold; Huber, Clemens R.; Timmel, Vincenzo; et al. (2024)
    Solar Physics
    Solar type V radio bursts are associated with type III bursts. Several processes have been proposed to interpret the association, electron distribution, and emission. We present the observation of a unique type V event observed by e-CALLISTO on 7 May 2021. The type V radio emission follows a group of U bursts. Unlike the unpolarized U bursts, the type V burst is circularly polarized, leaving room for a different emission process. Its starting edge drifts to higher frequency four times slower than the descending branch of the associated U burst. The type V processes seem to be ruled by electrons of lower energy. The observations conform to a coherent scenario where a dense electron beam drives the two-stream instability (causing type III emission) and, in the nonlinear stage, becomes unstable to another instability, previously known as the electron firehose instability (EFI). The secondary instability scatters some beam electrons into velocities perpendicular to the magnetic field and produces, after particle loss, a trapped distribution prone to electron cyclotron masering (ECM). A reduction in beaming and the formation of an isotropic halo are predicted for electron beams continuing to interplanetary space, possibly observable by Parker Solar Probe and Solar Orbiter.
  • The Eruption of 22 April 2021 as Observed by Solar Orbiter: Continuous Magnetic Reconnection and Heating After the Impulsive Phase
    Item type: Journal Article
    Rodriguez, Luciano; Warmuth, Alexander; Andretta, Vincenzo; et al. (2023)
    Solar Physics
    We report on one of the first solar-eruptive events that was simultaneously observed by three of the remote-sensing instruments onboard Solar Orbiter during the cruise phase. The Extreme Ultraviolet Imager (EUI) observed an eruption on 22 April 2021. The corresponding CME was recorded by the coronagraph Metis. Finally, the Spectrometer/Telescope for Imaging X-rays (STIX) sampled the associated X-ray flare, which was partially occulted. From the Earth, the eruption-source region was observed close to disk center. We provide an analysis of the eruption as observed by these various instruments. In particular, we show that in this eruption, continuous magnetic reconnection and heating have to be present even well after the impulsive phase. The need for this is derived from multiple independent lines of evidence – using both flare and CME observations – that have not been reported before for a single event. The combination of data from Solar Orbiter, as well as other space-based assets, clearly showcases the scientific potential for the science phase of Solar Orbiter, and the unique observations available.
  • X-ray polarization of solar flares measured with Rhessi
    Item type: Journal Article
    Suarez-Garcia, E.; Hajdas, W.; Wigger, C.; et al. (2006)
    Solar Physics
  • An Interpretation of the Coronal Holes’ Visibility in the Millimeter Wavelength Range
    Item type: Journal Article
    Brajša, R.; Benz, A. O.; Temmer, M.; et al. (2007)
    Solar Physics
  • Upflows in the Upper Solar Atmosphere: Invited Review
    Item type: Review Article
    Tian, Hui; Harra, Louise; Baker, Deborah; et al. (2021)
    Solar Physics
    Spectroscopic observations at extreme- and far-ultraviolet wavelengths have revealed systematic upflows in the solar transition region and corona. These upflows are best seen in the network structures of the quiet Sun and coronal holes, boundaries of active regions, and dimming regions associated with coronal mass ejections. They have been intensively studied in the past two decades because they are likely to be closely related to the formation of the solar wind and heating of the upper solar atmosphere. We present an overview of the characteristics of these upflows, introduce their possible formation mechanisms, and discuss their potential roles in the mass and energy transport in the solar atmosphere. Although past investigations have greatly improved our understanding of these upflows, they have left us with several outstanding questions and unresolved issues that should be addressed in the future. New observations from the Solar Orbiter mission, the Daniel K. Inouye Solar Telescope, and the Parker Solar Probe will likely provide critical information to advance our understanding of the generation, propagation, and energization of these upflows.
Publications1 - 10 of 38