Deriving the Electron Density of the Solar Corona from the Inversion of Total Brightness Measurements

Hayes, Andrew; Vourlidas, A.; Howard, R. A.

doi:10.1086/319029

Cited by 119 publications

(140 citation statements)

References 5 publications

Supporting

Mentioning

138

Contrasting

Order By: Relevance

“…It is a nuisance for coronal studies in the visible as it obscures the signal from CMEs and coronal streamers. Accurate removal of the F-corona is essential for the derivation of coronal density structure (e.g., Hayes et al 2001) but the current F-coronal models are unreliable, as LASCO/C3 observations have shown. The failure of the models stems from our incomplete understanding of the physical properties and distribution of the dust in the inner heliosphere.…”

Section: Science Question 8: 'What Is the Dust Environment In The Innmentioning

confidence: 99%

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

et al. 2015

View full text Add to dashboard Cite

mission designed to orbit as close as 7 million km (9.86 solar radii) from Sun center. WISPR employs a 95 • radial by 58 • transverse field of view to image the fine-scale structure of the solar corona, derive the 3D structure of the large-scale corona, and determine whether a dust-free zone exists near the Sun. WISPR is the smallest heliospheric imager to date yet it comprises two nested wide-field telescopes with large-format (2 K × 2 K) APS CMOS detectors to optimize the performance for their respective fields of view and to minimize the risk of dust damage, which may be considerable close to the Sun. The WISPR electronics are very flexible allowing the collection of individual images at cadences up to 1 second at perihelion or the summing of multiple images to increase the signal-to-noise when the spacecraft is further from the Sun. The dependency of the Thomson scattering emission of the corona on the imaging geometry dictates that WISPR will be very sensitive to the emission from plasma close to the spacecraft in contrast to the situation for imaging from Earth orbit. WISPR will be the first 'local' imager providing a crucial link between the large-scale corona and the in-situ measurements.

show abstract

Section: Science Question 8: 'What Is the Dust Environment In The Innmentioning

confidence: 99%

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

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Dolei et al 2015;Hayes et al 2001). We then derive the coronal electron temperatures starting from the electron density values and under the assumption of hydrostatic equilibrium (see e.g.…”

Section: Doppler Dimming Analysis Of Outflow Velocities In Coronal Stmentioning

confidence: 99%

Mapping the coronal hydrogen temperature in view of the forthcoming coronagraph observations by Solar Orbiter

Dolei

Spadaro

Ventura

2016

A&A

View full text Add to dashboard Cite

Context. Synergistic visible light and ultraviolet coronagraphic observations are essential to investigate the link of the Sun to the inner heliosphere through the study of the dynamic properties of the solar wind. Aims. We perform spectroscopic mapping of the outer solar corona to constitute a statistically significant database of neutral hydrogen coronal temperatures, which is suitable for overcoming the lack of spectrometric information in observations performed by coronagraphs that are solely equipped for visible light and ultraviolet imaging; these include the forthcoming Metis instrument on board Solar Orbiter. Methods. We systematically analysed neutral hydrogen Lyα line data that was obtained by UVCS/SOHO observations of the extended solar corona relevant to a lot of polar, mid-latitude and equatorial structures at different phases of solar activity, and collected far longer than a whole solar cycle (1996−2012). Results. We created a database consisting in both the neutral hydrogen temperature components, which are perpendicular and parallel to the radially symmetric coronal magnetic field lines, as a function of the heliocentric distance and polar angle and for different phases of the solar activity cycle. We validated the reliability of the constituted neutral hydrogen temperature database, investigating a new set of UVCS Lyα data with the Doppler dimming technique. The solar wind outflow velocities obtained by adopting both the neutral hydrogen temperature distribution directly derived from the observed Lyα profiles and those taken from our database well agree within the uncertainties.

show abstract

“…8) deserve a further and more thorough analysis, also considering that such differences are indeed larger than the estimated density uncertainties, which are well below a factor of two (cf. Hayes et al 2001;Strachan et al 2002). We need to take into account that the pB inversion assumes axisymmetry, so that the derived density represents a structure with significant depth along the line of sight.…”

Section: Diagnostics Of Physical Parametersmentioning

confidence: 99%

“…LASCO C2 pB images were also taken day by day from May 17 to May 22, 2004. The inversion of such pB data (see, e.g., Hayes et al 2001) provided daily electron density maps relevant to the portion of extended corona observed in UV, in the 2.25 to 6 R range of heliocentric distance. We also determined the electron density (N e ) below 2.25 R by adopting the method described by Parenti et al (2000), based on the dependence on N e of the ratio of the radiative and collisional components of the O vi 1032 Å line.…”

Section: Introductionmentioning

confidence: 99%

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Spadaro

Susino

Ventura

et al. 2007

A&A

Self Cite

View full text Add to dashboard Cite

Context. Investigating the physical properties of solar coronal streamers is important for understanding their role in the global magnetic structure of the extended solar atmosphere, as well as in the generation of the slow solar wind. Aims. We hope to contribute as completely as possible to the ongoing SOHO instruments campaign devoted to the study of the physical characteristics of coronal streamers at various heliocentric distances. Results. Electron densities and temperatures, H i and O vi kinetic temperatures, and outflow velocities were derived from the line intensities and widths, as well as from the O vi line intensity ratio in the 1.6−5 R range of heights, limited to the central region of the streamer. To our knowledge, the H i outflow velocities obtained in this work are the first ones determined inside a streamer structure. They are significantly lower than those of the O vi ions. This, together with the O vi kinetic temperatures that are much higher than the H i ones, suggest that the absorption of Alfvén waves at the ion cyclotron frequency might also occur inside streamers. Methods. We analyzed ultraviolet H iConclusions. In comparison with other streamers described in the literature, the structure examined in this work generally exhibits lower electron density and neutral hydrogen kinetic temperature. Conversely, the O vi kinetic temperature and outflow velocity radial profiles are consistent with the results for the other examined streamers.

show abstract

Deriving the Electron Density of the Solar Corona from the Inversion of Total Brightness Measurements

Cited by 119 publications

References 5 publications

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

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

Mapping the coronal hydrogen temperature in view of the forthcoming coronagraph observations by Solar Orbiter

Physical parameters of a mid-latitude streamer during the declining phase of the solar cycle

Contact Info

Product

Resources

About