INTERCHANGE RECONNECTION AND CORONAL HOLE DYNAMICS

Journal Article · Sat May 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/1/517· OSTI ID:21448917

Edmondson, J K; Antiochos, S K ^[1]; DeVore, C R ^[2]; Lynch, B J ^[3]

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1. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
2. Naval Research Laboratory, Washington, DC 20375 (United States)
3. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

We investigate the effect of magnetic reconnection between open and closed fields, often referred to as 'interchange' reconnection, on the dynamics and topology of coronal hole boundaries. The most important and most prevalent three-dimensional topology of the interchange process is that of a small-scale bipolar magnetic field interacting with a large-scale background field. We determine the evolution of such a magnetic topology by numerical solution of the fully three-dimensional MHD equations in spherical coordinates. First, we calculate the evolution of a small-scale bipole that initially is completely inside an open field region and then is driven across a coronal hole boundary by photospheric motions. Next the reverse situation is calculated in which the bipole is initially inside the closed region and driven toward the coronal hole boundary. In both cases, we find that the stress imparted by the photospheric motions results in deformation of the separatrix surface between the closed field of the bipole and the background field, leading to rapid current sheet formation and to efficient reconnection. When the bipole is inside the open field region, the reconnection is of the interchange type in that it exchanges open and closed fields. We examine, in detail, the topology of the field as the bipole moves across the coronal hole boundary and find that the field remains well connected throughout this process. Our results, therefore, provide essential support for the quasi-steady models of the open field, because in these models the open and closed flux are assumed to remain topologically distinct as the photosphere evolves. Our results also support the uniqueness hypothesis for open field regions as postulated by Antiochos et al. On the other hand, the results argue against models in which open flux is assumed to diffusively penetrate deeply inside the closed field region under a helmet streamer. We discuss the implications of this work for coronal observations.

• OSTI ID: 21448917
• Journal Information: Astrophysical Journal, Vol. 714, Issue 1; Other Information: DOI: 10.1088/0004-637X/714/1/517; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
PHOTOSPHERE
SOLAR SYSTEM EVOLUTION
SOLAR WIND
SUN
THREE-DIMENSIONAL CALCULATIONS
TOPOLOGY
ATMOSPHERES
EVOLUTION
FLUID MECHANICS
HYDRODYNAMICS
MAIN SEQUENCE STARS
MATHEMATICS
MECHANICS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR WINDS