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Astronomy & Astrophysics manuscript no. 3099 May 11, 2005 (DOI: will be inserted by hand later)

Summary: Astronomy & Astrophysics manuscript no. 3099 May 11, 2005
(DOI: will be inserted by hand later)
Evidence for Explosive Event Activity Originating in the
J.G. Doyle1, B. Ishak1, I. Ugarte-Urra1 , P. Bryans2, and H.P. Summers2
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
Department of Physics, University of Strathclyde, Glasgow, Scotland
the date of receipt and acceptance should be inserted later
Abstract. We report on a joint SUMER, CDS, TRACE study, concentrating on a region which shows prolonged
EUV explosive event (EE) activity in the transition region line N v 1238 A, yet little evidence of such activity in
another transition region line O v 629 A (formed at a similar temperature) which was observed simultaneously.
A possible explanation for the lack of major activity in the O v line in several explosive events could be that
they originate in the lower chromosphere. This is consistent with the enhancements in the C i 1249 A line and
with the findings of another study which reported time delays between the chromospheric and transition region
lines in some EE's using high cadence observations (10 s exposure time) obtained with the SUMER spectrometer
in H i Ly 6 (20 000 K) and S vi (200 000 K). Using the generalized collisional-radiative picture, including the
population of metastable levels, we derive the density dependent contribution function for both N v 1238 and
O v 629 for four values of the electron density; 106


Source: Armagh Observatory


Collections: Physics