Letter to the Editor
New insight into transition region dynamics via SUMER observations and numerical modelling
L. Teriaca 1,
J.G. Doyle 1,
R. Erdélyi 2 and
L.M. Sarro 3
Received 11 October 1999 / Accepted 2 November 1999
We explore the idea that the occurrence of nano-flares in a magnetic loop around the O VI formation temperature could explain the observed red-shift of mid-low transition region lines as well as the blue-shift observed in low coronal lines (K). Observations are compared to numerical simulations of the response of the solar atmosphere to an energy perturbation of ergs representing an energy release during magnetic reconnection in a 1-D semi-circular flux tube. The temporal evolution of the thermodynamic state of the loop is converted into C IV 1548, O VI 1032 and Ne VIII 770 line profiles in non-equilibrium ionization. Performing an integration over the entire period of simulations, a redshift of is found in C IV , while a blue-shift of and were derived for O VI and Ne VIII , respectively, in reasonable agreement with observations.
Key words: Magnetohydrodynamics (MHD) line: profiles Sun: activity Sun: corona Sun: transition region Sun: UV radiation
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© European Southern Observatory (ESO) 1999
Online publication: December 2, 1999