Imaging and Spectroscopic Investigations of a Solar Coronal Wave: Properties of the Wave Front and Associated Erupting Material

Abstract

Using spectral data from the Coronal Diagnostic Spectrometer (CDS) instrument on the Solar and Heliospheric Observatory spacecraft, we observe a coronal wave feature (often referred to as an EIT wave) that occurred in association with a solar eruption and flare on 1998 June 13. EUV images from the Transition Region and Coronal Explorer (TRACE) satellite show that the coronal wave consists of two aspects: (1) a ``bright wave,'' which shows up prominently in the TRACE difference images, moves with a velocity of approximately 200 km s<sup>-1</sup>, and is followed by a strong dimming region behind it and (2) a ``weak wave,'' which is faint in the TRACE images, has a velocity of about 500 km s^-1, and appears to disperse out of the bright wave. The weak wave passes through the CDS field of view but shows little or no line-of-sight motions in CDS spectra (velocities less than about 10 km s^-1). Only a small portion of the bright wave passes the CDS field of view, with the spectral lines showing insignificant shifts. A high-velocity CDS feature, however, occurs after the weak wave passes, which appears to correspond to ejection of cool, filament-like material in TRACE images. Our observations have similarities with a numerical simulation model of coronal waves presented by Chen et al., who suggest that coronal waves consist of a faster propagating, piston-driven portion and a more slowly propagating portion due to the opening of field lines associated with an erupting filament.