Preflare X-Ray Pulsations with Sources Outside the Main Flare Active Region

Abstract

Earlier, we showed that according to the nature of the location of sources of preflare X-ray pulsationsrelative to the main solar flare, events are divided into at least two types: in type I events, the sources ofpulsations and the main flare are in the same active region (AR) and in type II events they are in differentregions. This paper presents an analysis of a type II event in which, according to data from the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) space observatory, X-ray sources of preflare quasi-periodicpulsations (with a period P = 1.5 ± 0.1 min), which began at ~1802 UT, were located in AR 11884 in the WesternHemisphere, and the sources of the main flare M1.0 SOL2013-11-05T18:08 were located in AR 11890 inthe Eastern Hemisphere. The pulsations were also observed with the Gamma-Ray Burst Monitor (GBM)aboard the Fermi space observatory and the X-Ray Sensor (XRS) aboard the Geostationary OperationalEnvironmental Satellite (GOES), excluding the possibility of their artificial origin. According to the data ofthe Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) in the extremeultraviolet range, it was found that the sources of pulsations were located at the base of coronal jets that flowedout at velocities of ~100–1500 km/s. The distance between AR 11884 and AR 11890 was ~1.4 RS. It wouldtake ~17–250 min for the jet plasma to reach AR 11890, which is much longer than the time interval betweenthe onset of pulsations (jets) and the flare (~6 min). No loops connecting AR 11884 and AR 11890 wereobserved in the corona. Moreover, no connection of these regions by magnetic field lines extrapolated fromthe photosphere to the corona in the potential approximation was found. These arguments indicate that thejets (and associated pulsations) could not be the trigger for the flare. Thus, a vivid example of an event is presentedin which there was no physical connection between preflare X-ray pulsations (and jets) and the flarethat followed them. This event demonstrates the importance of spatially resolved observations in the study ofpulsations on the Sun and stars.