Detection and Diagnostics of a Coronal Shock Wave Driven by a Partial‐Halo Coronal Mass Ejection on 2000 June 28

Abstract

A fast partial-halo coronal mass ejection (CME) was observed on 2000 June 28 by instruments on the SOHO spacecraft. The CME leading edge and filamentary cold core were detected over the northwest limb at 2.32 R ⊙ by the SOHO UV Coronagraph Spectrometer (UVCS). The broad profile of the O VI λ1032 line gives evidence of a shock front at the leading edge, supporting the identification of white-light CME sharp leading edges as fast-mode shocks. Line-of-sight speeds are as high as 1500 km s -1 , comparable to the projected speed obtained from LASCO. Pumping of the O VI λ11032 by Lyβ (v = 1810 km s -1 ) and of O VI λ1037 by O VI λ1032 (v = 1648 km s -1 ) were detected, which provide diagnostics of outflow speed and density. The angle of the ejecta with the plane of the sky is obtained, combining the projected speed from LASCO with the line-of sight-speed, and varies between 7° and 46°. In the latter case the projected height of 2.32 R ⊙ was at an actual heliocentric distance of 3.6 R ⊙ . An associated solar energetic particle (SEP) event was observed at the L1 point following this CME. The abundance and charge-state data are consistent with a gradual shock-accelerated SEP event. A type II radio burst was observed at the same time the shock front was detected by UVCS. © 2005. The American Astronomical Society. All rights reserved.