Energetic Phenomena on the Sun

643 Pages·1989·18.6 MB·English

by  E. R. Priest, V. Gaizauskas, M. J. Hagyard, E. J. Schmahl (auth.), M. R. Kundu, B. Woodgate, E. J. Schmahl (eds.)

ENERGETIC PHENOMENA ON THE SUN
ASTROPHYSICS AND
SPACE SCIENCE LIBRARY
A SERIES OF BOOKS ON THE RECENT DEVELOPMENTS
OF SPACE SCIENCE AND OF GENERAL GEOPHYSICS AND ASTROPHYSICS
PUBLISHED IN CONNECTION WITH THE JOURNAL
SPACE SCIENCE REVIEWS
Editorial Board
R. L. F. BOYD, University College, London, England
W. B. BURTON, Sterrewacht, Leiden, The Netherlands
C. DE JAGER, University 0/ Utrecht, The Netherlands
J. KLECZEK, Czechoslovak Academy o/Sciences, Ondfejov, Czechoslavakia
Z. KOPAL, University o/Manchester, England
R. LOST, European Space Agency, Paris, France
L.I. SEDOV,Academy o/Sciences o/the U.S.S.R., Moscow, U.S.SR.
Z. SVESTKA, Laboratory for Space Research, Utrecht, The Netherlands
VOLUME 153
CURRENT RESEARCH
ENERGETIC PHENOMENA
ON THE SUN
Edited by
M. R. KUNDU
Astronomy Program, University ofM aryland at College Park,
Maryland, U.S.A.
B. WOODGATE
NASA/Goddard Space Flight Center,
Greenbelt, Maryland, U.S.A.
and
E. J. SCHMAHL
Astronomy Program, University ofM aryland at College Park,
Maryland, U.S.A .
..
KLUWER ACADEMIC PUBLISHERS
DORDRECHT / BOSTON / LONDON
Library of Congress Cataloging in Publication Data
Energetic phenomena on the sun I edited by Mukul R. Kundu and Bruce
Woodgate, and E.J. Schmahl.
p. cm. -- (Astrophysics and space science library; 153)
"A result of three meetings ... held at the Goddard Space Flight
Center on January 24-28, 1983, June 8-14, 1983, and February 13-17,
1984"--Foreword.
Includes bibliographies and index.
ISBN 0-7923-0172-2
1. Solar flares--Congresses. I. Kundu, Mukul Ranjan, 1930-
II. Woodgate, Bruce. III. Schmahl, E. J. IV. Series: Astrophysics
and space science library; v. 153.
QB526.F6E52 1989
523.7·5--dcI9 89-31037
ISBN-13:978-94-010-7548-0 e-ISBN-13:978-94-009-2331-7
DOl: 10.1 007/978-94-009-2331-7
Published by Kluwer Academic Publishers,
P.O. Box 17,3300 AA Dordrecht, The Netherlands.
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TABLE OF CONTENTS
FOREWORD.. • • • • . • . . • • . • •• • • . . •• • . • . . • • . • • • . •• • •• • •• • • . • . • . • . . . • • . • •. ix
INTRODUCTION. • • • • . . • • . . • • • • • • . • • • . • • • • . • • • • • • • • • • • . • • • . . • . • • • • • • . .• xii i
CHAPTER 1: PREFLARE ACTIVITy ••••••••••••••.••.••••••..•.••..••..••
1 • 1 INTRODUC TION. . • . • . • • . • • • . . • • . . . • • • . . • • . . . . • • • . . • . . • • • . • • . . • • • 7
1.2 MAGNETOHYDRODYNAMIC INSTABILITy.............................. 11
1.3 PREFLARE MAGNETIC AND VELOCITY FIELDS........................ 30
1.4 CORONAL MANIFESTATIONS OF PREFLARE ACTIVITy.................. 77
1 .5 REFERENCES. . • • . . • • • . • • • . • • • • • • • • • • • • . . . • • • . . • . • . • . • . • • . . • . . • • 112
CHAPTER 2: PARTICLE ACCELERATION •••••.•••..••••...•••..••••.••.•.• 127
2.1 INTRODUC TION. • • . • . • • • • • • • . • . . • • • • • . • . . • • • • • • . • • . . • . . . . . . • • . • • 13 1
2.2 PHENOMENA ASSOCIATED WITH MILDLY-RELATIVISTIC ELECTRONS ....•. 133
2.3 PHENOMENA ASSOCIATED WITH IONS AND RELATIVISTIC ELECTRONS
IN SOLAR FLARES. • . • . . • • • . • • • • • . • • . • . • • • • • • • • • • • • • • • • • • • • • • • • • 178
2.4 THEORETICAL STUDIES OF PARTICLE ACCELERATION ••••••••••....•• 197
2.5 ACHIEVEMENTS - OUTSTANDING QUESTIONS •......•.••..•...••.•.... 212
2.6 ACKNOWLEDGEMENTS. . . . . . . • • • . . • • • • • • • . • • • . . . • • • • . • . . . . • • • • . • • . . 215
2.7 REFERENCES. • • . • . . • . . . • . . • • • . • . • • • • • • • . • • . . . • • • . • • . • • • • • • . . • . . 216
CHAPTER 3: IMPULSIVE PHASE TRANSPORT ••••...•....••..•.••.•••..••.. 225
3.1 INTRODUCTION................................................. 229
3.2 IMPULSIVE PHASE OBSERVATIONS AND THEIR INTERPRETATION .....••• 234
3.3 THEORETICAL STUDIES OF TRANSPORT PROCESSES ••••...•.•.•....•.. 282
3.4 SUMMARY. • • • • . . . . . • • . • . • • . . • • . . • • . • • • • • . • . • • . • . . . . . . . . . • • • . • • • 294
3.5 REFERENCES. . . . . . • . . • • . . . . • . • . • . • • • • . . • . . . • • • • . • • . • . . • • • . • • • . • 296
vi TABLE OF CONTENTS
CHAPTER 4: CHROMOSPHERIC EXPLOSIONS ............................... 303
4.1 INTRODUCTION. . • • • . . • • . • • • . . • . • • • • . . • • . . . • . . • . • • . • . • . • • • . . • . . • 307
4.2 CRYSTAL SPECTROMETER EXPERIMENTS ............................. 312
4.3 DEBATE OF ISSUE 1 ............................................ 313
4.4 DEBATE OF ISSUE 2............................................ 342
4.5 DEBATE OF ISSUE 3............................................ 359
4.6 REFERENCES................................................... 373
CHAPTER 5: FLARE ENERGETICS ....................................... 377
5.1 INTRODUC TION. . • • • . • . . • . • . • • . . • . . • • • . . • • • . • . . • • • • • . . . . . • • . . . . • 384
5.2 ENERGETICS OF THE IMPULSIVE PHASE ............................ 391
5.3 THE ENERGETICS OF THE GRADUAL PHASE .......................... 413
5.4 RELATIONSHIPS AMONG THE PHASES ............................... 442
5.5 CHARACTERIZATION OF TOTAL FLARE ENERGy ....................... 445
5.6 CONCLUSIONS. . • . . • . . . . . • • • • • • . . • . • . . • • . • . . . • . . • . . • . . . . . . . • . . • . 451
5A. FLARES CHOSEN FOR THE ENERGETICS STUDy ....................... 455
5B. A REVIEW OF IMPULSIVE PHASE PHENOMENA ..•.•................... 473
5.7 ACKNOWLEDGEMENTS. . . • . . . . • . . . • . . . • • . • . . . • . . . . . . • . . . . . . • . . • . . •• 486
5.8 REFERENCES. . . • • . . . • . . • . . . • . . • . • . • • • . • • . . • • . . • . . • . • • . . • . . . . . . . 486
CHAPTER 6: CORONAL MASS EJECTIONSAND CORONAL STRUCTURES ...•..•.•. 493
6.1 INTRDOCUTION. . . . • . . • . . • . . . • • . . . • . . . • • . • . . . • . . . . . . . . . • • . • . . . • • 497
6.2 OBSERVATIONS................................................. 498
6.3 THE INITIATION OF CORONAL MASS EJECTIONS •••••.•••••••.••.•.. 531
6.4 MODELLING OF CORONAL MASS EJECTIONS AND POST-FLARE ARCHES ...• 543
TABLE OF CONTENTS vii
6.5 INTERPLANETARY EFFECTS OF CORONAL MASS EJECTIONS ••.•.••••••.• 569
6.6 THE SLOWLY VARYING CORONA NEAR SOLAR ACTIVITY MAXIMUM •••••••• 574
6.7 SUMMARY. • • • • • . . • . • . • • • • • • . . . . . . . . • . • . • . • . . . • . • . • . . • . . . . . . . • • • 586
6.8 ACKNOWLEDGEMENTS. . • • . • • • • . . . • • • . • • . . . • • . • . • . . • • • • • . • . . . . . . . . • 590
6.9 REF ERENCES. . . • . . • • • • • • • . . • . . . . . • • • • • . • • . • • • . • • • . • . . • . . . • • • • • • 591
CHAPTER 7: INTERCOMPARISON OF NUMERICAL MODELS OF FLARING
CORONAL LOOPS.......................................... 597
7.1 INTRODUCTION. . . . • • • • • . . • . . • • . . • • • . • • . • • • . . • • . • • • • • . . • • . . • • . • • 601
7.2 THE ORIGINAL BENCHMARK PROBLEM ....•...••.•...•••.•.•••..•••• 602
7.3 INITIAL SOLUTION COMPARISONS .....•..•.•.•••.•..••.••.••.••.•• 605
7.4 FINAL BENCHMARK PROBLEM AND SOLUTION COMPARISON .•.•...•.....• 608
7.5 CONCLUSIONS. . . . . . • . . • . . • • . . • • . . . • . . • • • • • • • . . • . . • . . • • . • • . . • • . . 610
7.6 REFERENCES. • • . • . • . . . • • . . . • . . . . . • • • . . . . . • . • . • • • . • • • • • • . . . . • . . • 612
SUBJECT INDEX ••••••••••••••••••••••••••••••.••••.••..••••..••.••••• 613
SMM PARTICIPANTS................................................... 627
FOREWORD
This publication is a result of three meetings, each 5 days long,
held at the Goddard Space Flight Center on January 24-28, 1983, June
8-14, 1983, and February 13-17, 1984.
The meetings were held in the interim between the full operations of
the Solar Maximum Mission (SMM) in 1980, and the renewed operations after
its repair in orbit in April 1984. Their general objectives were as
follows:
o Synthesize flare studies after three years of SMM data analysis.
Many analyses of individual flares and individual phenomena, often
jointly across many data sources had been published, but a need existed
for a broader synthesis and updating of our understanding of solar flares
since the Skylab Flare Workshops held several years earlier.
o Encourage a broader participation in the SMM data anlysis and
combine this more fully with theory and other data sources--data obtained
with other spacecraft such as the HINOTORI, P78-1, and ISEE-3
spacecrafts, and with the Very Large Array (VLA) and many other
ground-based instruments. Many coordinated data sets, unprecedented in
their breadth of coverage and multiplicity of sources, had been obtained
within the structure of the Solar Maximum Year (SMY).
o Stimulate joint studies, and publication in the general
scientific literature. The intended primary benefit was for informal
collaborations to be started or broadened at the Workshops with
subsequent publications.
o Provide a special publication resulting from this Workshop.
o Provide a starting point of understanding for planning renewed
full observations with the repaired SMM.
The widespread interest in the Workshop topics drew over 150 people
from 17 countries, which enabled the desired broad participation of
people, data sources and ideas to be achieved. It also led to
fragmentation of closely related subjects into topic groups in order to
allow reasonably sized groups for discussion, and to allow more time for
detailed discussion of each topic. The results of the studies of each
group form the chapters of this book. Table 1 shows the seven topics,
the topic leaders, and the sub-topics expressing the scope of each topic,
shown as a set of questions. The Workshop participants, are shown at the
back of the book. Some integration of topics occurred by having joint
meetings between topic groups and plenary sessions.
This volume is the product of research carried out by all the
workshop participants, and in particular of the dedicated efforts of all
x FOREWORD
the team leaders. We express our sincere thanks to Drs. E. J. Schmahl,
S. M. White and N. Gopalswamy for their generous help in various aspects
of the production of this volume; to Ms. Gloria Wharen of GSFC and Ms.
Betty J. Stevenson of U. MD. for the preparation of the manuscript; to
Dr. David Bohlin of NASA for providing financial support for the
workshops; to Goddard Space Flight Center, and the University of Maryland
for various administrative support services.
M. R. Kundu
B. Woodgate
Table SMM Workshop Topic Groups
Chapter Topic Sub Topics
Preflare Activity What changes in physical conditions can lead to instabilities?
What are typical pre-flare phenomena:
Leaders: E. Priest Photosphere: Velocity and magnetic shears?
and V. Gaizauskas Emerging flux?
Chromosphere. T.R.: UV fluctuations, down flows?
UV upflows?
Filament eruptions?
Corona: Soft X-ray increases-mechanism?
Early radio events-arch destabilizers?
2 Impulsive Phase What instabilities will occur first in plausible physical situations?
Acceleration of Particles Where is the primary energy release located?
What are the physical conditions in the loop implied by gamma
Leader: L. Vlahos ray lines and continuum?
What are accelerating mechanisms of the electrons and ions that
are allowed by the observations?
3 Impulsive Phase Are hard X -ray and UV bursts the result of electron beams or
Transport Processes conduction fronts')
What observational constraints exist on impulsive phase models?
Leader: R. Canfield What is the distribution of thermal and non-thermal plasma?
4 Chromospheric Explosions What are the observed motions during and after the impulsive
I
I phase"
Leader: G. Doschek What is the evidence for a high pressure region at this time?
I
How do thermal and mechanical energies compare, e,g" using
soft X -ray intensities and line shifts?
Can the total energy be contained?
5 Flare Energetics Is the maximum energy in the thermal phase greater than the
energy input by the impulsive phase?
Leader: S-T, Wu Is there theoretical need or observational evidence for post-
impulsive energy input?
Is there a time inconsistency between the end of the impulsive
phase and the maximum of the thermal phase?
6 Coronal Mass Ejections What is the relationship between coronal mass ejections and
and Coronal Structures flares and filament eruptions?
How can metric radio phenomena be integrated with other pre-
Leader: E, Hildner flare, flare and post-flare phenomena and observed coronal
structure?
What is the detailed structure of coronal mass ejections in the
corona and how do they appear in the interplanetary medium?
How are they initiated and related to other solar phenomena?
How well do models and observations of coronal transients
compare? How did the global corona evolve in the post-
maximum epoch of SMM~
7 Numerical Analysis Do the results of different flare modelling codes agree when
applied to the same initial conditions?
Leader: R, Kopp