X-Ray Expanding Features Associated with a Moreton Wave

Abstract

Abstract We report on the simultaneous observation of a Moreton wave in $\mathrm{H}\alpha$ and two kinds of coronal expanding features in soft X-rays near the solar limb. We consider the faster X-ray feature and the slower one as being an “X-ray wave” and “ejecta”, respectively. The chromospheric Moreton wave propagated on the solar disk at a speed of $1040 \pm 100 \,\mathrm{km} \,\mathrm{s}^{-1}$, whereas the coronal X-ray wave propagated outside of the disk toward the outer corona at $1400 \pm 250 \,\mathrm{km} \,\mathrm{s}^{-1}$. We identified the X-ray wave as MHD fast-mode shock. The fast-mode Mach number ($M_{\mathrm{f}}$) of the X-ray wave was also estimated to be about 1.13–1.31, which decreases during propagation. The timing when the $M_{\mathrm{f}}$ became “1” is consistent with that of the disappearance of the Moreton wave. Moreover, we discuss the 3-dimensional structure of the shock wave and the relation between the shock wave and the ejecta (and $\mathrm{H}\alpha$ filament eruptions).