The Geometric Spreading of Coronal Plumes and Coronal Holes

• Published in: Solar physics Vol. 180; no. 1-2; pp. 231 - 246
• Main Authors: Suess, S T, Poletto, G, Wang, A-h, Wu, S T, Cuseri, I
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.06.1998
• Subjects: Plumes; Solar physics; Studies
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1023/A:1005001618698

The geometric spreading in plumes and in the interplume region in coronal holes is calculated, using analytic and numerical theoretical models, between 1.0 and 5.0 R^sub ^. We apply a two-scale approximation that permits the rapid local spreading at the base of plumes (f^sub l^) to be evaluated separately from the global spreading (f^sub g^) imposed by coronal hole geometry. We show that f^sub l^ can be computed from a potential-field model and f^sub g^ can be computed from global magnetohydrodynamic simulations of coronal structure. The approximations are valid when the plasma beta is small with respect to unity and for a plume separation small with respect to a solar radius.[PUBLICATION ABSTRACT]