Search Publications
Coronal Holes, Footpoint Reconnection, and the Origin of the Slow (and Fast) Solar Wind
Wang, Y. -M.
The tendency for low-speed solar wind to show greater spatiotemporal variability and different compositional properties from high-speed wind has led to the prevailing idea of a bimodal solar wind, in which fast wind comes from coronal holes and slow wind comes from coronal streamers. We present observational evidence that most of the slow wind ori…
Decomposing the AIA 304 Å Channel into Its Cool and Hot Components
Antolin, Patrick; Auchère, Frédéric; Soubrié, Elie +2 more
The AIA 304 Å channel on board the Solar Dynamics Observatory (SDO) offers a unique view of ≈105 K plasma emitting in the He II 304 Å line. However, when observing off-limb, the emission of the (small) cool structures in the solar atmosphere (such as spicules, coronal rain and prominence material) can be of the same order as the surrounding hot co…
Super-Resolution of SOHO/MDI Magnetograms of Solar Active Regions Using SDO/HMI Data and an Attention-Aided Convolutional Neural Network
Xu, Yan; Wang, Haimin; Wang, Jason T. L. +4 more
Image super-resolution is an important subject in image processing and recognition. Here, we present an attention-aided convolutional neural network for solar image super-resolution. Our method, named SolarCNN, aims to enhance the quality of line-of-sight (LOS) magnetograms of solar active regions (ARs) collected by the Michelson Doppler Imager (M…
Multiwavelength Observations of Quasiperiodic Pulsations in the Impulsive Phase of an Eruptive Flare with the Hard X-Ray Imager On Board ASO-S and Other Instruments
Chen, Wei; Warmuth, Alexander; Su, Yang +7 more
We investigated the quasiperiodic pulsations (QPPs) of the X1.2 solar flare (SOL2023-01-06T00:57) based on multi-instrument observations, especially the Hard X-ray Imager (HXI) on board the Advanced Space-based Solar Observatory (ASO-S). The quasiperiod of ≈27 s was identified in hard X-rays (HXR) and microwaves using the Markov Chain Monte Carlo …
Observation of a Large-Scale Filament Eruption Initiated by Two Small-Scale Erupting Filaments Pushing Out from Below
Song, Yongliang; Zhang, Mei; Ji, Kaifan +9 more
Filament eruptions often result in flares and coronal mass ejections (CMEs). Most studies attribute the filament eruptions to their instabilities or magnetic reconnection. In this study, we report a unique observation of a filament eruption whose initiation process has not been reported before. This large-scale filament, with a length of about 360…
CME-Flare Association and the Role of Reconnection in CME Acceleration
Reva, Anton; Kirichenko, Alexey; Bogachev, Sergey +1 more
The association of coronal mass ejections (CMEs) with flares is related to the question of whether reconnection is necessary for the CME eruption. Indeed, if reconnection happens during a CME eruption, the plasma is heated, which can be observed as a flare. In this work, we study the CME-flare association using data obtained with the Mg XII spectr…
The "SEP Clock": A Discussion of First Proton Arrival Times in Wide-Spread Solar Energetic Particle Events
Posner, A.; Richardson, I. G.; Strauss, R. D. -T.
This work analyzes the appearance of wide-spread deka-MeV solar energetic proton (SEP) events, in particular the arrival of the first protons within ≈ 4.5 – 45 MeV measured at Earth–Sun L1, and their relationship with their relative solar source longitude. The definition of "wide-spread SEP event" for this study refers to events that are observed …
Reconstructing Sunspot Number by Forward-Modelling Open Solar Flux
Pope, Benjamin J. S.; Lockwood, Mike; Owens, Mathew J. +4 more
The open solar flux (OSF) is the integrated unsigned magnetic flux leaving the top of the solar atmosphere to form the heliospheric magnetic field. As the OSF modulates the intensity of galactic cosmic rays at Earth, the production rate of cosmogenic isotopes - such as 14C and 10Be stored in tree rings and ice sheets - is clo…
Mysteries of the 17 May 2012 Solar Event Responsible for GLE71. I. CME Development and the Role of Disturbances Excited by Eruptions
Firoz, K. A.; Grechnev, V. V.; Lysenko, A. L. +3 more
The SOL2012-05-17 event is remarkable in that it caused one of two ground-level enhancements (GLE71) in Solar Cycle 24. Despite the efforts spent studying this solar event, some aspects of it remain unclear. This relates to the development of a coronal mass ejection (CME), the history of the shock wave, and the flare. Our measurements reveal the f…
Tomography of the Solar Corona with the Metis Coronagraph II: Three-Dimensional Reconstructions of the Electron Density and Comparison with Reconstructions Based on LASCO-C2
Susino, Roberto; Romoli, Marco; De Leo, Yara +13 more
We carried out tomographic reconstructions of the three-dimensional distribution of the electron density of the solar corona based on white light polarized brightness (pB) images taken by the Metis coronagraph on board the Solar Orbiter (SolO) mission. We selected three different time intervals during 2022, and further implemented independent sync…