Temporal variability in the electron density at the solar transition region
M.E. Pérez 1,
J.G. Doyle 1,
E. O'Shea 2 and
F.P. Keenan 2
Received 23 July 1999 / Accepted 6 October 1999
The electron density as measured in the transition region of a coronal hole, a `quiet' Sun region at disk center plus an active region shows variations of up to a factor of two at Te 1.5 105 K, lasting at most only a few minutes. There is remarkable agreement between the number of such variations, their temporal variability and duration in the coronal hole and `quiet' Sun datasets, consistent with an earlier bright point study. There appears to be evidence of super-granular cells, with the increases in electron density occurring along the network boundaries. At some locations, periodicities of between 8 and 16 min are visible in the electron density variations. We associate these variations with the sites of explosive events.
Key words: line: profiles Sun: activity Sun: corona Sun: transition region Sun: UV radiation
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© European Southern Observatory (ESO) 1999
Online publication: November 16, 1999