The Wide-Field Imager for Solar Probe Plus (WISPR)

Vourlidas, A.; Howard, R. A.; Plunkett, S. P.; Korendyke, C. M.; Thernisien, A.; Wang, Dennis; Rich, N.; Carter, Michael T.; Chua, D.; Socker, D. G.; Linton, M. G.; Morrill, J. S.; Lynch, S.; Thurn, Adam; Duyne, Peter Van; Hagood, R.; Clifford, Greg; Grey, Phares J.; Velli, Marco; Liewer, Paulett C.; Hall, J. R.; DeJong, E.; Mikić, Z.; Rochus, Pierre; Mazy, Emmanuel; Bothmer, V.; Rodmann, J.

doi:10.1007/s11214-014-0114-y

Cited by 187 publications

(155 citation statements)

References 80 publications

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“…The method holds promise for improving the extraction of quantitative information from shocks in the corona using remote sensing observations. It can readily use observations from different vantage points, including from the imagers (Howard et al, 2013;Vourlidas et al, 2016) aboard the upcoming Solar Orbiter (Müeller et al, 2013) and Solar Probe Plus (Fox et al, 2016) missions to be compared with direct in situ measurements from these missions. The technique will also greatly improve the results from any future joint coronagraphic imaging and off-limb spectroscopy of shocks (Bemporad and Mancuso, 2011;Vourlidas and Bemporad, 2012).…”

Section: Discussionmentioning

confidence: 99%

The density compression ratio of shock fronts associated with coronal mass ejections

Kwon

Vourlidas

2018

J. Space Weather Space Clim.

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-We present a new method to extract the three-dimensional electron density profile and density compression ratio of shock fronts associated with coronal mass ejections (CMEs) observed in white light coronagraph images. We demonstrate the method with two examples of fast halo CMEs (∼2000 km s À1 ) observed on 2011 March 7 and 2014 February 25. Our method uses the ellipsoid model to derive the threedimensional geometry and kinematics of the fronts. The density profiles of the sheaths are modeled with double-Gaussian functions with four free parameters, and the electrons are distributed within thin shells behind the front. The modeled densities are integrated along the lines of sight to be compared with the observed brightness in COR2-A, and a x 2 approach is used to obtain the optimal parameters for the Gaussian profiles. The upstream densities are obtained from both the inversion of the brightness in a pre-event image and an empirical model. Then the density ratio and Alfvénic Mach number are derived. We find that the density compression peaks around the CME nose, and decreases at larger position angles. The behavior is consistent with a driven shock at the nose and a freely propagating shock wave at the CME flanks. Interestingly, we find that the supercritical region extends over a large area of the shock and lasts longer (several tens of minutes) than past reports. It follows that CME shocks are capable of accelerating energetic particles in the corona over extended spatial and temporal scales and are likely responsible for the wide longitudinal distribution of these particles in the inner heliosphere. Our results also demonstrate the power of multi-viewpoint coronagraphic observations and forward modeling in remotely deriving key shock properties in an otherwise inaccessible regime.

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Section: Discussionmentioning

confidence: 99%

The density compression ratio of shock fronts associated with coronal mass ejections

Kwon

Vourlidas

2018

J. Space Weather Space Clim.

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“…We also present a brief description of the instruments and the requirements. The detailed specifics of the instruments are covered in the accompanying instrument papers (McComas et al 2014;Vourlidas et al 2015;Bale et al 2015, this issue;Kasper et al 2015, this issue; hereafter M2014, V2015, B2015, and K2015, respectively).…”

Section: Spp Observations Investigations and Requirementsmentioning

confidence: 99%

The Solar Probe Plus Mission: Humanity’s First Visit to Our Star

et al. 2015

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Solar Probe Plus (SPP) will be the first spacecraft to fly into the low solar corona. SPP's main science goal is to determine the structure and dynamics of the Sun's coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Understanding these fundamental phenomena has been a top-priority science goal for over five decades, dating back to the 1958 Simpson Committee Report. The scale and concept of such a mission has been revised at intervals since that time, yet the core has always been a close encounter with the Sun. The mission design and the technology and engineering developments enable SPP to meet its science objectives to: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind; and (3) Explore mechanisms that accelerate and transport energetic particles. The SPP mission was confirmed in March 2014 and is under development as a part of NASA's Living with a Star (LWS) Program. SPP is scheduled for launch in mid-2018, and will perform 24 orbits over a 7-year nominal mission duration. Seven Venus gravity assists gradually reduce SPP's perihelion from 35 solar radii (R S ) for the first orbit to <10 R S for the final three orbits. In this paper we present the science, B N.J. Fox

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“…well within the perihelion distance range of sunskirters. Its instruments, some of which will carry out in situ measurements, include the Wide-Field Imager for Solar Probe Plus, WISPR, whose two telescopes will provide 36 pixel −1 views covering 2.2-20 R from the Sun at perihelion (Vourlidas et al 2016).…”

Section: Space-based Facilitiesmentioning

confidence: 99%

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

et al. 2017

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This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all ob- jects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun's centre, equal to half of Mercury's perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground-and space-based facilities that will allow us to address those science topics.

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The Wide-Field Imager for Solar Probe Plus (WISPR)

Cited by 187 publications

References 80 publications

The density compression ratio of shock fronts associated with coronal mass ejections

The density compression ratio of shock fronts associated with coronal mass ejections

The Solar Probe Plus Mission: Humanity’s First Visit to Our Star

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

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