Search Publications
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…
Spectral and Imaging Observations of a C2.3 White-Light Flare from the Advanced Space-Based Solar Observatory (ASO-S) and the Chinese HαSolar Explorer (CHASE)
Lei, Shijun; Chen, Wei; Feng, Li +27 more
Solar white-light flares are characterized by an enhancement in the optical continuum, which are usually large flares (X- and M-class flares). Here, we report a small C2.3 white-light flare (SOL2022-12-20T04:10) observed by the Advanced Space-based Solar Observatory and the Chinese HαSolar Explorer (CHASE). This flare exhibits an increase of ≈ 6.4…
Spectra and Anisotropy of Solar Energetic Protons During GLE #65 on 28 October, 2003 and GLE #66 on 29 October, 2003
Mishev, Alexander L.; Koldobskiy, Sergey A.; Larsen, Nicholas +1 more
Solar Cycle 23 was the most active in ground-level enhancements (GLEs) with 16 events registered by the global neutron monitor network. In this paper, we study a very active period in October–November, 2003, which revealed an intense solar activity burst that led to several eruptive processes and produced a sequence of three GLEs. By applying stat…
Reconstruction of Carrington Rotation Means of Open Solar Flux over the Past 154 Years
Lockwood, Mike; Owens, Mat
We generate reconstructions of signed open solar flux (OSF) for the past 154 years using observations of geomagnetic activity. Previous reconstructions have been limited to annual resolution, but this is here increased by a factor of more than 13 by using averages over Carrington rotation (CR) intervals. We use two indices of geomagnetic activity,…
The Sun's Large-Scale Flows I: Measurements of Differential Rotation & Torsional Oscillation
Basu, Sarbani; Pevtsov, Alexei A.; DeRosa, Marc L. +13 more
We have developed a comprehensive catalog of the variable differential rotation measured near the solar photosphere. This catalog includes measurements of these flows obtained using several techniques: direct Doppler, granule tracking, magnetic pattern tracking, global helioseismology, as well as both time-distance and ring-diagram methods of loca…
Origin of the Chromospheric Umbral Waves in Sunspots
Xu, Zhe; Xue, Zhike; Yan, Xiaoli +5 more
Oscillations are ubiquitous in sunspots and the associated higher atmospheres. However, it is still unclear whether these oscillations are driven by the external acoustic waves (p-modes) or generated by the internal magnetoconvection. To obtain clues about the driving source of umbral waves in sunspots, we analyzed the spiral wave patterns (SWPs) …
Triangulation of Hard X-Ray Sources in an X-Class Solar Flare with ASO-S/HXI and Solar Orbiter/STIX
Massa, Paolo; Krucker, Säm; Chen, Wei +4 more
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 n…