# THE EFFECT OF RECONNECTION ON THE STRUCTURE OF THE SUN’S OPEN–CLOSED FLUX BOUNDARY

## Abstract

Global magnetic field extrapolations are now revealing the huge complexity of the Sun's corona, and in particular the structure of the boundary between open and closed magnetic flux. Moreover, recent developments indicate that magnetic reconnection in the corona likely occurs in highly fragmented current layers, and that this typically leads to a dramatic increase in the topological complexity beyond that of the equilibrium field. In this paper we use static models to investigate the consequences of reconnection at the open–closed flux boundary (“interchange reconnection”) in a fragmented current layer. We demonstrate that it leads to efficient mixing of magnetic flux (and therefore plasma) from open and closed field regions. This corresponds to an increase in the length and complexity of the open–closed boundary. Thus, whenever reconnection occurs at a null point or separator of this open–closed boundary, the associated separatrix arc of the so-called S-web in the high corona becomes not a single line but a band of finite thickness within which the open–closed boundary is highly structured. This has significant implications for the acceleration of the slow solar wind, for which the interaction of open and closed field is thought to be important, and may also explain the coronalmore »

- Authors:

- Division of Mathematics, University of Dundee, Dundee (United Kingdom)
- Heliophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771 (United States)

- Publication Date:

- OSTI Identifier:
- 22522409

- Resource Type:
- Journal Article

- Journal Name:
- Astrophysical Journal

- Additional Journal Information:
- Journal Volume: 805; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; EQUILIBRIUM; EXTRAPOLATION; FINE STRUCTURE; LAYERS; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIC RECONNECTION; MORPHOLOGY; PARTICLES; PLASMA; POTENTIALS; SOLAR CORONA; SOLAR WIND; SUN

### Citation Formats

```
Pontin, D. I., and Wyper, P. F., E-mail: dpontin@maths.dundee.ac.uk, E-mail: peter.f.wyper@nasa.gov.
```*THE EFFECT OF RECONNECTION ON THE STRUCTURE OF THE SUN’S OPEN–CLOSED FLUX BOUNDARY*. United States: N. p., 2015.
Web. doi:10.1088/0004-637X/805/1/39.

```
Pontin, D. I., & Wyper, P. F., E-mail: dpontin@maths.dundee.ac.uk, E-mail: peter.f.wyper@nasa.gov.
```*THE EFFECT OF RECONNECTION ON THE STRUCTURE OF THE SUN’S OPEN–CLOSED FLUX BOUNDARY*. United States. doi:10.1088/0004-637X/805/1/39.

```
Pontin, D. I., and Wyper, P. F., E-mail: dpontin@maths.dundee.ac.uk, E-mail: peter.f.wyper@nasa.gov. Wed .
"THE EFFECT OF RECONNECTION ON THE STRUCTURE OF THE SUN’S OPEN–CLOSED FLUX BOUNDARY". United States. doi:10.1088/0004-637X/805/1/39.
```

```
@article{osti_22522409,
```

title = {THE EFFECT OF RECONNECTION ON THE STRUCTURE OF THE SUN’S OPEN–CLOSED FLUX BOUNDARY},

author = {Pontin, D. I. and Wyper, P. F., E-mail: dpontin@maths.dundee.ac.uk, E-mail: peter.f.wyper@nasa.gov},

abstractNote = {Global magnetic field extrapolations are now revealing the huge complexity of the Sun's corona, and in particular the structure of the boundary between open and closed magnetic flux. Moreover, recent developments indicate that magnetic reconnection in the corona likely occurs in highly fragmented current layers, and that this typically leads to a dramatic increase in the topological complexity beyond that of the equilibrium field. In this paper we use static models to investigate the consequences of reconnection at the open–closed flux boundary (“interchange reconnection”) in a fragmented current layer. We demonstrate that it leads to efficient mixing of magnetic flux (and therefore plasma) from open and closed field regions. This corresponds to an increase in the length and complexity of the open–closed boundary. Thus, whenever reconnection occurs at a null point or separator of this open–closed boundary, the associated separatrix arc of the so-called S-web in the high corona becomes not a single line but a band of finite thickness within which the open–closed boundary is highly structured. This has significant implications for the acceleration of the slow solar wind, for which the interaction of open and closed field is thought to be important, and may also explain the coronal origins of certain solar energetic particles. The topological structures examined contain magnetic null points, separatrices and separators, and include a model for a pseudo-streamer. The potential for understanding both the large scale morphology and fine structure observed in flare ribbons associated with coronal nulls is also discussed.},

doi = {10.1088/0004-637X/805/1/39},

journal = {Astrophysical Journal},

issn = {0004-637X},

number = 1,

volume = 805,

place = {United States},

year = {2015},

month = {5}

}