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Observation of the Solar Corona Using Radio Scintillation with the Akatsuki Spacecraft: Difference Between Fast and Slow Wind
Matsumoto, Takuma; Pätzold, Martin; Imamura, Takeshi +8 more
The properties of the coronal plasma at heliocentric distances of 1.5 - 8.9 R⊙ (solar radii) were studied with radio-occultation observations using JAXA's Akatsuki spacecraft in 2016. Physical parameters that characterize the solar wind were retrieved from the intensity-scintillation time series by fitting a theoretical spectrum to the …
Extracting the Heliographic Coordinates of Coronal Rays Using Images from WISPR/Parker Solar Probe
Riley, P.; Qiu, J.; Stenborg, G. +5 more
The Wide-field Imager for Solar Probe (WISPR) onboard Parker Solar Probe (PSP), observing in white light, has a fixed angular field of view, extending from 13.5∘ to 108∘ from the Sun and approximately 50∘ in the transverse direction. In January 2021, on its seventh orbit, PSP crossed the heliospheric current sheet …
Analysis of the Evolution of a Multi-Ribbon Flare and Failed Filament Eruption
Schmieder, Brigitte; Joshi, Reetika; Chandra, Ramesh +5 more
How filaments form and erupt are topics about which solar researchers have wondered for more than a century and they are still open to debate. We present observations of a filament formation, its failed eruption, and the associated flare (SOL2019-05-09T05:51) that occurred in active region (AR) 12740 using data from the Solar Dynamics Observatory …
Multiwavelength Observations of a Partial Filament Eruption on 13 June 2011
Li, Dong; Zhang, Qingmin; Zhang, Yanjie +2 more
In this paper, we report the multiwavelength observations of the partial filament eruption associated with a C1.2 class flare in NOAA active region 11236 on 13 June 2011. The event occurred at the eastern limb in the field of view (FOV) of Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) spacecraft and was close to t…
Is the Subsurface Meridional Flow Zero at the Equator?
Komm, R.
We study the subsurface meridional flow and its divergence from the surface to a depth of about 16 Mm at the equator and its variation with the solar cycle derived with ring-diagram analysis applied to Michelson Doppler Imager (MDI) Dynamics Program, Global Oscillation Network Group (GONG), and Helioseismic and Magnetic Imager (HMI) Dopplergrams. …
Rate of Change of Large-Scale Solar-Wind Structure
Riley, Pete; Lockwood, Mike; Owens, Mathew J. +5 more
Quantifying the rate at which the large-scale solar-wind structure evolves is important for both understanding the physical processes occurring in the corona and for space-weather forecast improvement. Models of the global corona and heliosphere typically assume that the ambient solar-wind structure is steady and corotates with the Sun, which is g…
Near-Earth Interplanetary Coronal Mass Ejections and Their Association with DH Type II Radio Bursts During Solar Cycles 23 and 24
Joshi, Bhuwan; Moon, Yong-Jae; Cho, Kyung-Suk +2 more
We analyse the characteristics of interplanetary coronal mass ejections (ICMEs) during Solar Cycles 23 and 24. The present analysis is primarily based on the near-Earth ICME catalogue (Richardson and Cane, 2010). An important aspect of this study is to understand the near-Earth and geoeffective aspects of ICMEs in terms of their association (type …
Searching for a Solar Source of Magnetic-Field Switchbacks in Parker Solar Probe's First Encounter
Mandrini, C. H.; Raouafi, N. E.; Velli, M. +9 more
Parker Solar Probe observations show ubiquitous magnetic-field reversals closer to the Sun, often referred to as "switchbacks". The switchbacks have been observed before in the solar wind near 1 AU and beyond, but their occurrence was historically rare. PSP measurements below ∼ 0.2 AU show that switchbacks are, however, the most prominent structur…
A Review of the Extended EUV Corona Observed by the Sun Watcher with Active Pixels and Image Processing (SWAP) Instrument
Berghmans, David; West, Matthew J.; Mierla, Marilena +7 more
The Sun Watcher with Active Pixels and Image Processing (SWAP) instrument onboard ESA's PRoject for On Board Autonomy 2 (PROBA2) has provided the first uncompressed, high-cadence, continuous, large field-of-view observations of the extended extreme-ultraviolet (EUV) corona for over a complete solar cycle. It has helped shape our understanding of t…
White-Light Coronal Imaging at the 21 August 2017 Total Solar Eclipse
Pasachoff, Jay M.; Rušin, Vojtech
We describe the solar corona as imaged in the 21 August 2017 total solar eclipse from sites in Oregon and Illinois, USA separated by nearly one hour. Our composite images, each made from dozens of individual frames, show helmet streamers, nearly radially oriented narrow rays, and polar coronal holes filled with polar plumes. The Ludendorff flatten…