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Solar Physics

, Volume 187, Issue 2, pp 261–302 | Cite as

A new view of the solar outer atmosphere by the Transition Region and Coronal Explorer

  • C.J. Schrijver
  • A.M. Title
  • T.E. Berger
  • L. Fletcher
  • N.E. Hurlburt
  • R.W. Nightingale
  • R.A. Shine
  • T.D. Tarbell
  • J. Wolfson
  • L. Golub
  • J.A. Bookbinder
  • E.E. DeLuca
  • R.A. McMullen
  • H.P. Warren
  • C.C. Kankelborg
  • B.N. Handy
  • B. De Pontieu
Article

Abstract

The Transition Region and Coronal Explorer (TRACE) – described in the companion paper by Handy et al. (1999) – provides an unprecedented view of the solar outer atmosphere. In this overview, we discuss the initial impressions gained from, and interpretations of, the first million images taken with TRACE. We address, among other topics, the fine structure of the corona, the larger-scale thermal trends, the evolution of the corona over quiet and active regions, the high incidence of chromospheric material dynamically embedded in the coronal environment, the dynamics and structure of the conductively dominated transition region between chromosphere and corona, loop oscillations and flows, and sunspot coronal loops. With TRACE we observe a corona that is extremely dynamic and full of flows and wave phenomena, in which loops evolve rapidly in temperature, with associated changes in density. This dynamic nature points to a high degree of spatio-temporal variability even under conditions that traditionally have been referred to as quiescent. This variability requires that coronal heating can turn on and off on a time scale of minutes or less along field-line bundles with cross sections at or below the instrumental resolution of 700 km. Loops seen at 171 Å (∼1 MK) appear to meander through the coronal volume, but it is unclear whether this is caused by the evolution of the field or by the weaving of the heating through the coronal volume, shifting around for periods of up to a few tens of minutes and lighting up subsequent field lines. We discuss evidence that the heating occurs predominantly within the first 10 to 20 Mm from the loop footpoints. This causes the inner parts of active-region coronae to have a higher average temperature than the outer domains.

Keywords

Transition Region Wave Phenomenon Coronal Loop Coronal Heating Outer Domain 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • C.J. Schrijver
    • 1
  • A.M. Title
  • T.E. Berger
    • 1
  • L. Fletcher
    • 1
  • N.E. Hurlburt
    • 1
  • R.W. Nightingale
    • 1
  • R.A. Shine
    • 1
  • T.D. Tarbell
    • 1
  • J. Wolfson
    • 1
  • L. Golub
    • 2
  • J.A. Bookbinder
    • 2
  • E.E. DeLuca
    • 2
  • R.A. McMullen
    • 2
  • H.P. Warren
    • 2
  • C.C. Kankelborg
    • 3
  • B.N. Handy
    • 3
  • B. De Pontieu
    • 4
  1. 1.Dept. H1-12Stanford-Lockheed Institute for Space ResearchPalo AltoU.S.A
  2. 2.Smithsonian Astrophysical ObservatoryCambridgeU.S.A
  3. 3.Department of PhysicsMontana State University–BozemanBozemanU.S.A
  4. 4.Max Planck Institut für Extraterrestrische PhysikGarching bei MünchenGermany

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