Heavier Ions Move Faster In Coronal Holes

Heavier Ions Move Faster In Coronal Holes

. Outflow speeds at different distances over the solar poles for hydrogen atoms (dark gray, H0) and ionized oxygen ( light gray, O5+). Here the distances are given in units of the solar radius. These data, taken in late 1996 and early 1997 with the SOHO UVCS instrument, show that the heavier oxygen ions move out of coronal holes at faster speeds than the lighter protons, and that the oxygen ions attain supersonic velocities within 2.5 solar radii from the Sun center. The solid lines denote the proton outflow speed derived from mass flux conservation; for a time-steady flow, the product of the density, speed and flow-tube area should be constant. (Courtesy of the SOHO UVCS consortium. SOHO is a project of international collaboration between ESA and NASA.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University