The Solar Wind and Its Magnetic Sources at Sunspot Maximum

Wang, Y.-M.; Sheeley, N. R.

doi:10.1086/368302

Cited by 62 publications

(49 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is in contradiction with the usual polytropic models (e.g. Kopp & Holzer 1976) but in good agreement with observations as shown by Wang (1995) and Wang & Sheeley (2003).…”

Section: Discussionsupporting

confidence: 51%

Nonradial and nonpolytropic astrophysical outflows

Sauty¹,

Lima

Iro

et al. 2005

A&A

View full text Add to dashboard Cite

Abstract. Exact axisymmetric analytical solutions of the governing MHD equations for magnetized and rotating outflows are applied to the solar wind during solar minimum as observed by ULYSSES. Using the spacecraft data, the latitudinal dependences of physical quantities such as the density, velocity, magnetic field and temperature are analytically described. The self-similar solutions are then compared to the global structure of the wind from one solar radius to 5 AU and beyond, including consistently the rotation of the outflow. The model makes it possible to describe the initial flaring of the magnetic dipolar structure, reproducing in a satisfactory way the observed profiles of the velocity, density and temperature with heliocentric distance. Finally, this model is in agreement with the conjecture that the solar wind should not be collimated at large distances, even close to its rotational axis.

show abstract

“…This is in contradiction with the usual polytropic models (e.g. Kopp & Holzer 1976) but in good agreement with observations as shown by Wang (1995) and Wang & Sheeley (2003).…”

Section: Discussionsupporting

confidence: 51%

Nonradial and nonpolytropic astrophysical outflows

Sauty¹,

Lima

Iro

et al. 2005

A&A

View full text Add to dashboard Cite

show abstract

“…The transverse pressure gradient is proportional to κΠ, and lower values of Π are needed to open the lines radially and at the same time as the flaring is higher the velocity is lower as discussed in . This last result is unexpected from polytropic wind theory where a larger flaring leads to larger velocities Kopp & Holzer (1976) but this is precisely what has been observed for the fast component of the solar wind during the minimum and the maximum of the last solar cycles (see Wang 1995;Wang & Sheeley 2003).…”

Section: Behaviour Of the Solutions With κ Andsupporting

confidence: 61%

Nonradial and nonpolytropic astrophysical outflows

Sauty

Trussoni

Tsinganos

2004

A&A

View full text Add to dashboard Cite

Abstract. By means of a nonlinear separation of the variables in the governing full set of the magnetohydrodynamic (MHD) equations for axisymmetric plasmas we analyse an exact model for magnetized and rotating outflows that are hotter and overpressured at their axis. These outflows start subsonically and subAlfvénically from the central gravitating source and its surrounding accretion disk. Subsequently, they accelerate thermally and magnetocentrifugally and thus cross the appropriate MHD critical points, reaching high values of the Alfvén Mach number. Three types of solutions are found: (a) collimated jettype outflows from efficient magnetic rotators with the flow confined by the magnetic hoop stress; (b) radially expanding windtype outflows analogous to the solar wind, from inefficient magnetic rotators or strongly overpressured sources; (c) terminated solutions with increasing amplitude of oscillations in the width of the beam. In contrast to previously studied underpressured outflows, the transition from collimated jets to uncollimated winds is not continuous in the appropriate parametric space with a gap where no stationary solution is found. Superfast at infinity solutions are filtered by three critical surfaces corresponding to the three known limiting characteristics or separatrices of MHD wind theory. Collimated and terminated solutions cross the slow, Alfvén and fast magneto-acoustic critical points. Radially expanding solutions cross the slow and Alfvén critical points while the last boundary condition is imposed by requiring that the pressure vanishes at infinity.

show abstract

“…Neugebauer et al (2002) found that active regions and coronal holes are the principal source regions of solar wind around the maximum of solar activity. Wang & Sheeley (2003) then showed, using PFSS calculations, that the solar wind from active regions comes from highly concentrated magnetic flux in the low corona which rapidly expands at greater altitude (see also Schrijver & DeRosa 2003). The type III bursts and associated open flux tubes in our events give an illustration of that finding.…”

Section: Open Magnetic Flux Tubes and Coronal Holesmentioning

confidence: 52%

“…While such models are clearly insufficient to represent the sheared and twisted magnetic field configurations in active regions, they have been successful in connecting coronal and interplanetary structures on larger scales. For example, Schrijver & DeRosa (2003) and Wang & Sheeley (2003) used such models to identify the origin of the heliospheric magnetic field, while Wang et al (2006) showed that they represent the large-scale open magnetic flux tubes which guide SEP through the corona. In these models the transition between the coronal and the interplanetary magnetic field is supposed to take place at a spherical source surface, outside of which the magnetic field is frozen into the radially flowing solar wind.…”

Section: Radio Identification Of Magnetic Flux Tubes In the Coronamentioning

confidence: 99%

Open magnetic flux tubes in the corona and the transport of solar energetic particles

Klein¹,

Krucker²,

Lointier³

et al. 2008

A&A

View full text Add to dashboard Cite

We investigate how magnetic fields guide energetic particles through the corona into interplanetary space and eventually to a spacecraft near the Earth. A set of seven simple particle events is studied, where energetic electrons (30-500 keV; Wind spacecraft) or protons (5-55 MeV; SoHO) were released together with low-energy electron beams producing metric-to-kilometric type III emission. Imaging of the coronal (metre-wave) part of this emission with the Nançay Radioheliograph is used to identify the open flux tubes that guide these electrons -and by inference all particles detected at 1 AU. Open coronal field lines are also computed using potential magnetic field extrapolations, constrained by a source surface and by SoHO/MDI measurements in the photosphere (code by Schrijver and DeRosa). We find that in all events the type III radio sources lie in open flux tubes in the potential magnetic field extrapolations. The open flux tubes are rooted in small parts of the parent active region, covering a heliocentric angle of a few degrees in the photosphere. But they expand rapidly above the neighbouring closed magnetic structures and cover several tens of degrees in longitude on the source surface. Some of these open field lines are found to connect the parent active region to the footpoint of the nominal Parker spiral on the source surface, within the uncertainty of about ±10• inherent to the evaluation of its connection longitude. This is so even when the parent active region is as far as 50• away. In two cases where the coronal flux tubes point to high heliolatitudes, the detection of Langmuir waves at the Wind spacecraft in the ecliptic plane suggests that the interplanetary field lines curve down to the ecliptic before reaching 1 AU. We conclude that non-radial open flux tubes in the corona can transport particles over several tens of degrees in longitude even in simple impulsive particle events. In all events we studied, potential magnetic field models give an adequate description of these structures.

show abstract

The Solar Wind and Its Magnetic Sources at Sunspot Maximum

Cited by 62 publications

References 16 publications

Nonradial and nonpolytropic astrophysical outflows

Nonradial and nonpolytropic astrophysical outflows

Nonradial and nonpolytropic astrophysical outflows

Open magnetic flux tubes in the corona and the transport of solar energetic particles

Contact Info

Product

Resources

About