X-ray observations of a large-scale solar coronal shock wave

¹ Mullard Space Science Laboratory, University College London, Holmbury Saint Mary, Dorking, Surrey, RH5 6NT, UK
² Institute of Space & Astronautical Science, 3–1–1 Yoshinodai, Sagamihara, Kanagawa 229–8510, Japan
³ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany

Corresponding author: J. I. Khan, jkhan@spd.aas.org

Received: 14 September 2001
Accepted: 27 November 2001

Abstract

We report observations of a propagating disturbance in the solar corona observed in emission in soft X-ray images from the Yohkoh Soft X-ray Telescope (SXT). The disturbance was associated with a flare which began at about 09:04 UT on 1997 November 03. This flare was associated with a type II radio burst observed at decimetric-dekametric wavelengths by the Astrophysikalisches Institut Potsdam Radio Spectrograph. Hα data from Kanzelhöhe Solar Observatory show that a Moreton wave was associated with this event. Moreover, Solar and Heliospheric Observatory Extreme Ultraviolet Imaging Telescope (EIT) 195 Å data show an `EIT wave' associated with this event. Extrapolations of the leading edge of the propagating soft X-ray disturbance show a close association with both of these wave features. The soft X-ray disturbance is observed to travel with a speed of about 546 km s^-1. Using Nançay Radioheliograph data we directly determine the source locations of the type II radio burst. These are found to be located close to the soft X-ray disturbance and show motions consistent with the soft X-ray motions. These results lead us to conclude that the “SXT wave” is the coronal counterpart of a Moreton wave, analogous to EIT waves, i.e., it is the first confirmed direct observation of a solar coronal shock wave in X-rays.