Coronal Shocks of November 1997 Revisited: The CME-Type II Timing Problem

Abstract

We re-examine observations bearing on the origin of metric type II bursts for six impulsive solar events in November 1997. Previous analyses of these events indicated that the metric type IIs were due to flares (either blast waves or ejecta). Our point of departure was the study of Zhang et al. (2001) based on the Large Angle and Spectrometric Coronagraph's C1 instrument (occulting disk at 1.1 R(sub-O)) that identified the rapid acceleration phase of coronal mass ejections (CMEs) with the rise phase of soft X-ray light curves of associated flares. We find that the inferred onset of rapid CME acceleration in each of the six cases occurred 1-3 min before the onset of metric type II emission, in contrast to the results of previous studies for certain of these events that obtained CME launch times ~25-45 min earlier than type II onset. The removal of the CME-metric type II timing discrepancy in these events and, more generally, the identification of the onset of the rapid acceleration phase of CMEs with the flare impulsive phase undercuts a significant argument against CMEs as metric type II shock drivers. In general, the six events exhibited: (1) ample evidence of dynamic behavior [soft X-ray ejecta, extreme ultra-violet imaging telescope (EIT) dimming onsets, and wave initiation (observed variously in H-alpha, EUV, and soft X-rays)] during the inferred fast acceleration phases of the CMEs, consistent with the cataclysmic disruption of the low solar atmosphere one would expect to be associated with a CME; and (2) an organic relationship between EIT dimmings (generally taken to be source regions of CMEs) and EIT waves (which are highly associated with metric type II bursts) indicative of a CME-driver scenario.

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Document Details

Document Type
Technical Report
Publication Date
Aug 24, 2004
Accession Number
ADA443539

Entities

People

  • B. J. Thompson
  • Edward W. Cliver
  • Jinlun Zhang
  • N. V. Nitta

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • C4I

DTIC Thesaurus Topics

  • Air Force Research Laboratories
  • Atmospheres
  • Blast
  • Blast Waves
  • Contrast
  • Coronal Mass Ejections
  • Ejecta
  • Ejection
  • Emission
  • Fluid Mechanics
  • Observation
  • Physics
  • Soft X Rays
  • Solar Atmosphere
  • Solar Physics
  • Wave Phenomena
  • X Rays

Fields of Study

  • Physics

Readers

  • Nuclear Civil Defense.
  • Solar Physics

Technology Areas

  • AI & ML
  • AI & ML - Bayesian Inference
  • Space