Search Publications
A coronal mass ejection encountered by four spacecraft within 1 au from the Sun: ensemble modelling of propagation and magnetic structure
Al-Haddad, Nada; Riley, Pete; Richter, Ingo +11 more
Understanding and predicting the structure and evolution of coronal mass ejections (CMEs) in the heliosphere remains one of the most sought-after goals in heliophysics and space weather research. A powerful tool for improving current knowledge and capabilities consists of multispacecraft observations of the same event, which take place when two or…
Observation of a propagating slow magnetoacoustic wave in a coronal plasma fan with SDO/AIA and SolO/EUI
Nakariakov, Valery M.; Kolotkov, Dmitrii Y.; Zhong, Sihui +1 more
Simultaneous observations of a propagating disturbance of EUV intensity, with SDO/AIA at 171 Å and SolO/EUI-HRIEUV at 174 Å, are investigated. The disturbance moves outwards along a plasma fan structure in active region AR 12941 on February 7th 2022, at 12:45-14:15 UT. The spacecraft line-of-sight separation is 19°. The variation of the EUV intens…
Highly collisional regions determined by interplanetary magnetic field structures
Lai, H. R.; Russell, C. T.; Jia, Y. D. +3 more
Submicron debris released in interplanetary collisions gets charged in the solar wind and generates disturbances to the magnetic field environment. The unique magnetic field disturbances, named interplanetary field enhancements (IFEs) are recorded by many spacecraft. In this study, we have developed a novel model to trace the IFEs to their origins…
First joint X-ray solar microflare observations with NuSTAR and Solar Orbiter/STIX
Krucker, Säm; Jeffrey, Natasha L. S.; Grefenstette, Brian W. +5 more
We present the first joint spectral and imaging analysis of hard X-ray (HXR) emission from three microflares observed by the Nuclear Spectroscopic Telescope ARray (NuSTAR) and Solar Orbiter/Spectrometer/Telescope for Imaging X-rays (STIX). We studied 5 joint spectra from GOES A7, B1, and B6 class microflares from active region AR12765 on 2020 June…
Multi-spacecraft observations of shocklets at an interplanetary shock
Vainio, R.; Horbury, T.; Dresing, N. +5 more
Interplanetary (IP) shocks are fundamental building blocks of the heliosphere, and the possibility to observe them in situ is crucial to address important aspects of energy conversion for a variety of astrophysical systems. Steepened waves known as shocklets are known to be important structures of planetary bow shocks, but they are very rarely obs…
Self-consistent nanoflare heating in model active regions: MHD avalanches
Hood, A. W.; Threlfall, J.; Reid, J.
Straightened cylindrical models of coronal loops have been standard for decades, and shown to support nanoflare-like heating, but the influence of geometric curvature in models upon the heating produced has not been discussed in depth. Heating, its spatiotemporal distributions, and the associated mechanisms responsible are discussed, and compared …
Two-spacecraft detection of short-period decayless kink oscillations of solar coronal loops
Berghmans, David; Nakariakov, Valery M.; Verbeeck, Cis +2 more
Decayless kink oscillations of an ensemble of loops are captured simultaneously by the High Resolution Imager (HRI) of the Extreme Ultraviolet Imager (EUI) and the Atmospheric Imaging Assembly (AIA) from 22:58 UT on 2021 November 5 to 00:27 UT on 2021 November 6. Oscillations are analysed by processing image sequences taken by the two instruments …
Path-lengths in the quiet Sun transition region using O IV lines from IRIS
Del Zanna, Giulio; Rao, Yamini K.; Mason, Helen E. +1 more
We use spectroscopic diagnostics to determine different plasma parameters in the transition region of the quiet Sun. The electron number density from O IV lines using high-resolution spectral observations from the Interface Region Imaging Spectrograph (IRIS) are estimated to be around 1010 cm-3, in agreement with literature v…
Flux conservation, radial scalings, Mach numbers, and critical distances in the solar wind: magnetohydrodynamics and Ulysses observations
Verscharen, Daniel; Velli, Marco; Bale, Stuart D.
One of the key challenges in solar and heliospheric physics is to understand the acceleration of the solar wind. As a super-sonic, super-Alfvénic plasma flow, the solar wind carries mass, momentum, energy, and angular momentum from the Sun into interplanetary space. We present a framework based on two-fluid magnetohydrodynamics to estimate the flu…
On the slow solar wind with high Alfvénicity: from composition and microphysics to spectral properties
D'Amicis, Raffaella; Bruno, Roberto; Matteini, Lorenzo
Alfvénic fluctuations are very common features in the solar wind and are found especially within the main portion of fast-wind streams while the slow wind usually is less Alfvénic and more variable. In general, the fast and slow winds show many differences, which span from the large-scale structure to small-scale phenomena, including also a differ…