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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.08] Expansion Factors in Coronal Holes and Plume/Interplume UVCS Observations

G. Poletto, G. Corti (Osservatorio Astrofisico, Firenze, ITALY), G. Noci (Universita di Firenze, ITALY), J. Kohl (Center for Astrophysics, Boston, MA), S. Suess (NASA Marshall Space Flight Center, AL)

We show that expansion factors in plumes and coronal hole areas devoid of plumes are nearly equal because the plasma beta is <<1. Hence, the overall coronal hole expansion factor is equal to the expansion factors of its densest structures. UVCS plume and interplume observations of coronal holes are illustrated, with the purpose of showing the data capabilities. Integration along the line of sight, through a medium containing high and low pressure regions, and the rapid decrease with heliocentric distance of plume intensity, presently hinder an observational determination of the expansion factors between 1.5 and 2 solar radii.

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