Search Publications
Initiation and Early Kinematic Evolution of Solar Eruptions
Inhester, B.; Cheng, X.; Ding, M. D. +5 more
We investigate the initiation and early evolution of 12 solar eruptions, including six active-region hot channel and six quiescent filament eruptions, which were well observed by the Solar Dynamics Observatory, as well as by the Solar Terrestrial Relations Observatory for the latter. The sample includes one failed eruption and 11 coronal mass ejec…
Magnetic Reconnection during the Post-impulsive Phase of a Long-duration Solar Flare: Bidirectional Outflows as a Cause of Microwave and X-Ray Bursts
Reeves, Katharine K.; Chen, Bin; Yu, Sijie +5 more
Magnetic reconnection plays a crucial role in powering solar flares, production of energetic particles, and plasma heating. However, where the magnetic reconnections occur, how and where the released magnetic energy is transported, and how it is converted to other forms remain unclear. Here we report recurring bidirectional plasma outflows located…
Sun-Heliosphere Observation-based Ionization Rates Model
McComas, D. J.; Bzowski, M.; Tokumaru, M. +1 more
The solar wind (SW) and the extreme ultraviolet (EUV) radiation modulate fluxes of interstellar and heliospheric particles inside the heliosphere both in time and in space. Understanding this modulation is necessary to correctly interpret measurements of particles of interstellar origin inside the heliosphere. We present a revision of heliospheric…
Magnetic Flux of Active Regions Determining the Eruptive Character of Large Solar Flares
Veronig, Astrid M.; Hou, Yijun; Li, Ting +3 more
We establish the largest eruptive/confined flare database to date and analyze 322 flares of Geostationary Operational Environmental Satellite class M1.0 and larger that occurred during 2010-2019, i.e., almost spanning all of solar cycle 24. We find that the total unsigned magnetic flux ( ${{\rm{\Phi }}}_{\mathrm{AR}}$ ) of active regions (ARs) is …
Magnetic Field Dependence of Bipolar Magnetic Region Tilts on the Sun: Indication of Tilt Quenching
Banerjee, Dipankar; Jha, Bibhuti Kumar; Karak, Bidya Binay +1 more
The tilt of the bipolar magnetic region (BMR) is crucial in the Babcock-Leighton process for the generation of the poloidal magnetic field in the Sun. Based on the thin flux-tube model of the BMR formation, the tilt is believed to be caused by the Coriolis force acting on the rising flux tube of the strong toroidal magnetic field from the base of …
Coronal Magnetic Field Topology from Total Solar Eclipse Observations
Druckmüller, Miloslav; Boe, Benjamin; Habbal, Shadia
Measuring the global magnetic field of the solar corona remains exceptionally challenging. The fine-scale density structures observed in white-light images taken during total solar eclipses are currently the best proxies for inferring the magnetic field direction in the corona from the solar limb out to several solar radii (R⊙). We pres…
The Complex Space Weather Events of 2017 September
Hajra, Rajkumar; Tsurutani, Bruce T.; Lakhina, Gurbax S.
Interplanetary coronal mass ejections (ICMEs), magnetic clouds (MCs), sheaths, corotating interaction regions (CIRs), solar wind high-speed streams (HSSs), fast forward shocks (FSs), reverse waves (RWs), stream interfaces, and heliospheric current sheet crossings detected upstream of the Earth and their geoeffectiveness are studied during 2017 Sep…
Estimation of the Physical Parameters of a CME at High Coronal Heights Using Low-frequency Radio Observations
Vourlidas, Angelos; Mondal, Surajit; Oberoi, Divya
Measuring the physical parameters of coronal mass ejections (CMEs), particularly their entrained magnetic field, is crucial for understanding their physics and for assessing their geoeffectiveness. At the moment, only remote sensing techniques can probe these quantities in the corona, the region where CMEs form and acquire their defining character…
Fine Structure of a Solar Type II Radio Burst Observed by LOFAR
Zucca, Pietro; Vocks, Christian; Mann, Gottfried +6 more
Shock waves in the solar corona are closely associated with coronal mass ejections and flares. The longest-known and frequently studied signatures of coronal shock waves are metric type II radio bursts, which provide information on the shock driver and ambient plasma conditions. We report on outstanding high frequency/time resolution LOw Frequency…
What is the Solar Wind Frame of Reference?
Wimmer-Schweingruber, Robert F.; Matteini, Lorenzo; Berger, Lars +6 more
Various solar wind ion species move with different speeds and theoretical considerations as well as limited observations in a region close to the Sun show that heavy solar wind ions tend to flow faster than protons, at least in less-aged fast solar wind streams. The solar wind flow carries the frozen-in interplanetary magnetic field (IMF) and this…