The excitation of 5-min oscillations in the solar corona

¹ Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria
e-mail: teimuraz.zaqarashvili@oeaw.ac.at; maxim.khodachenko@oeaw.ac.at
² Group of Astrophysics, Institute of Physics, UMCS, ul. Radziszewskiego 10, 20-031 Lublin, Poland
e-mail: kmur@kft.umcs.lublin.pl
³ ASC/Flash Center, The University of Chicago, 5640 S. Ellis Ave, Chicago, IL 60637, USA
e-mail: dongwook@flash.uchicago.edu
⁴ Abastumani Astrophysical Observatory at Ilia State University, Kazbegi ave. 2a, Tbilisi, Georgia

Received: 13 July 2010
Accepted: 28 January 2011

Abstract

Aims. We aim to study excitation of the observed  ~5-min oscillations in the solar corona by localized pulses that are launched in the photosphere.

Methods. We solve the full set of nonlinear one-dimensional Euler equations numerically for the velocity pulse propagating in the solar atmosphere that is determined by the realistic temperature profile.

Results. Numerical simulations show that an initial velocity pulse quickly steepens into a leading shock, while the nonlinear wake in the chromosphere leads to the formation of consecutive pulses. The time interval between the arrivals of two neighboring pulses to a detection point in the corona is approximately 5 min. Therefore, the consecutive pulses may result in the  ~5-min oscillations that are observed in the solar corona.

Conclusions. The  ~5-min oscillations observed in the solar corona can be explained in terms of consecutive shocks that result from impulsive triggers launched within the solar photosphere by granulation and/or reconnection.