A&A 446, 327-331 (2006)
Repetitive occurrence of explosive events at a coronal hole boundaryJ. G. Doyle1, M. D. Popescu1, 2 and Y. Taroyan1
1 Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2 Astronomical Institute of the Romanian Academy, RO-040557 Bucharest 28, Romania
(Received 14 July 2005 / Accepted 20 September 2005)
SUMER/SoHO data taken at a coronal hole boundary show a repetitive explosive event occurrence rate of around 3 min increasing to over 5 min towards the end of the activity. We suggest that the neighbouring oppositely directed closed and open field lines at the coronal hole boundary undergo repetitive reconnection seen as a sequence of explosive events. The repetitive reconnection may be triggered by transverse oscillations of the flux tubes in the closed field line region. These oscillations periodically separate and bring together the closed and open field lines on the two sides of the coronal hole boundary. An important indicator favouring the interpretation in terms of a kink mode is the observed increase in the oscillation period.
Key words: Sun: activity: -- Sun: oscillations -- Sun: transition region -- Sun: UV radiation -- line: profiles
© ESO 2006