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Astronomy & Astrophysics manuscript no. 3703 September 23, 2005 (DOI: will be inserted by hand later)

Summary: Astronomy & Astrophysics manuscript no. 3703 September 23, 2005
(DOI: will be inserted by hand later)
Nanoflare heating of coronal loops: hydrodynamic response
and observational consequences
Y. Taroyan 1 , S. J. Bradshaw 2 , and J. G. Doyle 1
1 Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2 Space and Atmospheric Physics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7
Received 27 June 2005 / Accepted 15 September 2005
Abstract. The plasma response inside a semicircular coronal loop heated by nanoflares is examined. The loop is thermally and
gravitationally stratified. The losses due to thermal conduction and radiation are balanced by localised energy pulses randomly
deposited along the loop. The initial stage of the loop evolution during which the temperature along the loop gradually increases
from chromospheric to coronal values is completed about 20 minutes after the start of the heating. The random heating produces
a thin transition region which is in a continuous motion. The profiles of the C ##, O ##, Ne #### and Mg # resonance lines, which
have peak formation temperatures covering the upper transition region and lower corona, are synthesised. The line shifts and
the average shifts are calculated and compared with the observations. It is shown that the nanoflare heating mechanism may
reproduce the observed dynamics of the transition region lines. The calculated and previously measured average Doppler shift
values are in good agreement for the studied spectral lines except for the C ## line. Possible reasons for this discrepancy are
discussed. The study also shows that the nanoflares could contribute to the oscillation power often seen in the mHz ranges. The
power peak of the resulting oscillations is near 2 mHz.


Source: Armagh Observatory


Collections: Physics