Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-22T21:36:59.887Z Has data issue: false hasContentIssue false
  • English
  • Français

A Simple Model of a Coronal Hole

Published online by Cambridge University Press:  25 April 2016

D. Summers
D. Summers*
Affiliation:
Department of Applied Mathematics, University of Sydney
*
*On leave from Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada.
Get access Rights & Permissions [Opens in a new window]

Extract

A coronal hole is a region of the solar corona characterised by diverging magnetic fields of single polarity and lower-than-average densities (and probably temperatures). It is now generally accepted that coronal holes are the source of high-speed streams in the solar wind (Munro and Withbroe 1972, Kopp and Holzer 1976, Steinolfson and Tandberg-Hanssen 1977, Munro and Jackson 1977; see Pneuman 1980 for references to most of the theoretical and observational papers on coronal holes since their recognition in 1968). We consider an infinitesimal field-aligned flow tube with cross-sectional area A(r) where r is the heliocentric radius (Figure 1), and we adopt the functional form

A(r)/A(r ) = (r/r0)8

where r is the coronal base radius, and 5 is a parameter which measures the divergence of the flow. If s = 2 then the flow is purely spherically symmetric, while if s > 2 the flow is more strongly divergent as is expected to be the case for a coronal hole. The cross-section of a typical coronal hole is shown schematically in Figure 2.

Type
Contributions
Information
Publications of the Astronomical Society of Australia , Volume 4 , Issue 4 , 1982 , pp. 379 - 382
Copyright
Copyright © Astronomical Society of Australia 1982

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adams, W.M., and Sturrock, P.A., Astrophys. J., 202, 259 (1975).CrossRefGoogle Scholar
Kopp, R.A., and Holzer, T.E., Solar Phys., 49, 43 (1976).CrossRefGoogle Scholar
Munro, R. H., and Jackson, B.V., Astrophys. J., 213, 874 (1977).CrossRefGoogle Scholar
Munro, R.H., and Withbroe, G.L., Astrophys. J., 176, 511 (1972).CrossRefGoogle Scholar
Parker, E.N., Interplanetary Dynamical Processes, Interscience, New York-London (1963).Google Scholar
Pneuman, G.W., Astron. Astrophys., 81, 161 (1980).Google Scholar
Steinolfson, R.S., and Tandberg-Hanssen, E., Solar Phys., 55, 99 (1977).CrossRefGoogle Scholar