Characterization of the White-light Brightness of the F-corona between 5° and 24° Elongation

Stenborg, G.; Howard, R. A.; Stauffer, Johnathan R.

doi:10.3847/1538-4357/aacea3

Cited by 25 publications

(49 citation statements)

References 33 publications

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“…Given the rapid movement of the spacecraft, combining many images to determine a stable background will not effectively remove the F-corona in WISPR. Adapting a technique developed by (Stenborg et al 2018) on SECCHI HI-1 data, a background removal technique has been applied to WISPR images allowing for transient K-corona features to be highlighted. Like the calibrations, this technique is preliminary and will continue to be improved as more data are collected.…”

Section: White-light Observationsmentioning

confidence: 99%

WISPR Imaging of a Pristine CME

Hess

Rouillard

Kouloumvakos

et al. 2020

ApJS

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The Wide-field Imager for Solar Probe (WISPR) on board the Parker Solar Probe (PSP) observed a CME on 2018 November 01, the first day of the initial PSP encounter. The speed of the CME, approximately 200-300 km s −1 in the WISPR field of view, is typical of slow, streamer blowout CMEs. This event was also observed by the LASCO coronagraphs. WISPR and LASCO view remarkably similar structures that enable useful cross-comparison between the two data sets as well as stereoscopic imaging of the CME. Analysis is extended to lower heights by linking the white-light observations to EUV data from AIA, which reveal a structure that erupts more than a full day earlier before the CME finally gathers enough velocity to propagate outward. This EUV feature appears as a brightness enhancement in cooler temperatures such as 171Å, but as a cavity in nominal coronal temperatures such as 193Å. By comparing this circular, dark feature in 193Å to the dark, white-light cavity at the center of the eruption in WISPR and LASCO, it can be seen that this is one coherent structure that exists prior to the eruption in the low corona before entering the heliosphere and likely corresponds to the core of the magnetic flux rope. It is also believed that the relative weakness of the event contributed to the clarity of the flux rope in WISPR, as the CME did not experience impulsive forces or strong interaction with external structures that can lead to more complex structural evolution.

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Section: White-light Observationsmentioning

confidence: 99%

WISPR Imaging of a Pristine CME

Hess

Rouillard

Kouloumvakos

et al. 2020

ApJS

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“…The number of escaping electrons is reduced and the ion part of the signal exceeds the electron one. This results in a bipolar signal where the first part is typically called "pre-spike" (Collette et al, 2015;Thayer et al, 2016). A larger number of escaping ions change the polarity of the signal.…”

Section: Antenna Signal Shapesmentioning

confidence: 99%

Dust observations with antenna measurements and its prospects for observations with Parker Solar Probe and Solar Orbiter

et al. 2019

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Abstract. The electric and magnetic field instrument suite FIELDS on board the NASA Parker Solar Probe and the radio and plasma waves instrument RPW on the ESA Solar Orbiter mission that explore the inner heliosphere are sensitive to signals generated by dust impacts. Dust impacts have been observed using electric field antennas on spacecraft since the 1980s and the method was recently used with a number of space missions to derive dust fluxes. Here, we consider the details of dust impacts, subsequent development of the impact generated plasma and how it produces the measured signals. We describe empirical approaches to characterise the signals and compare these in a qualitative discussion of laboratory simulations to predict signal shapes for spacecraft measurements in the inner solar system. While the amount of charge production from a dust impact will be higher near the Sun than observed in the interplanetary medium before, the amplitude of pulses is determined by the recovery behaviour that is different near the Sun since it varies with the plasma environment.

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“…Top four panels show the running-difference LASCO C2 image (a and e) and LASCO C3 image (b and f) of the CME. Bottom four panels display WISPR-I (c and g) and WISPR-O (d and h) Level-3 images for which an F-corona removal has been applied (seeStenborg et al 2018; Hess et al 2019). On panels (e), (f), (g) and (h), we superimpose the 3D FR fitting(Figure 3) that we use to perform the 3D reconstruction of the CME.…”

mentioning

confidence: 99%

Modeling the Early Evolution of a Slow Coronal Mass Ejection Imaged by the Parker Solar Probe

Rouillard

Poirier

Lavarra

et al. 2020

ApJS

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During its first solar encounter, the Parker Solar Probe (PSP ) acquired unprecedented up-close imaging of a small Coronal Mass Ejection (CME) propagating in the forming slow solar wind. The CME originated as a cavity imaged in extreme ultraviolet that moved very slowly (< 50 km/s) to the 3-5 solar radii (R ) where it then accelerated to supersonic speeds. We present a new model of an erupting Flux Rope (FR) that computes the forces acting on its expansion with a computation of its internal magnetic field in three dimensions. The latter is accomplished by solving the Grad-Shafranov equation inside two-dimensional cross sections of the FR. We use this model to interpret the kinematic evolution and morphology of the CME imaged by PSP. We investigate the relative role of toroidal forces, momentum coupling, and buoyancy for different assumptions on the initial properties of the CME. The best agreement between the dynamic evolution of the observed and simulated FR is obtained by modeling the two-phase eruption process as the result of two episodes of poloidal flux injection. Each episode, possibly induced by magnetic reconnection, boosted the toroidal forces accelerating the FR out of the corona. We also find that the drag induced by the accelerating solar wind could account for about half of the acceleration experienced by the FR. We use the model to interpret the presence of a small dark cavity, clearly imaged by PSP deep inside the CME, as a low-density region dominated by its strong axial magnetic fields.

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Characterization of the White-light Brightness of the F-corona between 5° and 24° Elongation

Cited by 25 publications

References 33 publications

WISPR Imaging of a Pristine CME

WISPR Imaging of a Pristine CME

Dust observations with antenna measurements and its prospects for observations with Parker Solar Probe and Solar Orbiter

Modeling the Early Evolution of a Slow Coronal Mass Ejection Imaged by the Parker Solar Probe

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