Abstract


  GLOBAL OSCILLATIONS OF FLARE LOOPS OBSERVED WITH IRIS

  H. Tian, Peking University, TIANHUI924@GMAIL.COM
  P. Young, George Mason University,
  K. Reeves, Harvard-Smithsonian Center for Astrophysics,
  T. Wang, Catholic University of America,
  J. He, Peking University,

Quasi-periodic pulsations (QPPs) have been frequently reported in solar flares and are usually suggested to result from intermittent magnetic reconnection or MHD waves. Using data taken by the Interface Region Imaging Spectrograph, we have identified clear oscillations of the intensity and Doppler shift of the Fe xxi 1354.08 A line in both the impulsive and decay phases of a flare. The oscillation period is around 25 seconds. Remarkably similar oscillation has also been detected in the soft X-ray flux recorded by GOES, suggesting that the flare loops oscillate as a whole. We also find a phase shift of pi /2 (1/4 period) between the Doppler shift oscillation and the intensity/GOES oscillations. Our preliminary analysis suggests that this oscillation might be consistent with the global sausage mode, although a (vertical) kink mode scenario cannot be completely excluded. Our observation supports the MHD wave interpretation of QPPs.