Solar Prominences

169 Pages·1974·6.639 MB·English

by  Einar Tandberg-Hanssen (auth.)

SOLAR PROMINENCES
GEOPHYSICS AND
ASTROPHYSICS MONOGRAPHS
AN INTERNATIONAL SERIES OF FUNDAMENTAL TEXTBOOKS
Editor
B. M. MCCORMAC, Lockheed Palo Alto Research Laboratory, Palo Alto, Calif., U.S.A.
Editorial Board
R. GRANT ATHA Y, High Altitude Observatory, Boulder, Colo., U.S.A.
P. J. COLEMAN, JR., University of California, Los Angeles, Calif., U.S.A.
D. M. HUNTEN, Kif( Peak National Observatory, Tucson, Ariz., U.S.A.
J. KLECZEK, Czechoslovak Academy of Sciences, Ondfejov, Czechoslovakia
R. LUST, Institutfiir Extraterrestrische Physik, Garching-Miinchen, F.R.G.
R. E. MUNN, Meteorological Service of Canada, Toronto, Ont., Canada
Z. SVESTKA, Fraunhofer Institute, Freiburg im Breisgau, F.R.G.
G. WEILL, Institut d'Astrophysique, Paris, France
VOLUME 12
SOLAR PROMINENCES
by
EINAR TANDBERG-HANSSEN
High Altitude Observatory, National Center for Atmospheric Research,
Boulder, Colo., U.S.A.
D. REIDEL PUBLISHING COMPANY
DORDRECHT-HOLLAND / BOSTON-U.S.A.
Library of Congress Catalog Card Number 73-88593
ISBN -13: 978-90-277-0400-9 e-ISBN -13: 978-94-010-2136-4
DOl: 10.1007/978-94-010-2136-4
Published by D. Reidel Publishing Company,
P.O. Box 17, Dordrecht, Holland
Sold and distributed in the U.S.A., Canada and Mexico
by D. Reidel Publishing Company, Inc.
306 Dartmouth Street, Boston,
Mass. 02116, U.S.A.
All Rights Reserved
Copyright © 1974 by D. Reidel Publishing Company. Dordrecht, Holland
No part of this book may be reproduced in any form, by print, photoprint, microfilm,
or any other means, without written permission from the publisher
To Else and Karin
TABLE OF CONTENTS
PREFACE IX
LIST OF SYMBOLS AND PHYSICAL CONSTANTS XI
ABBREVIA TIONS FOR JOURNALS XIV
CHAPTER I. INTRODUCTION
1.1. Historical Background
1.2. Definitions 2
1.3. Morphological Classifications 5
CHAPTER II. OBSERVATIONAL DATA 11
2.1. Spectra 11
2.2. Motions 23
2.3. Magnetic Fields 30
2.4. Radio, EUV and X-Ray Observations 45
CHAPTER III. MODELS 50
3.1. Quiescent Prominences 50
3.2. Active Prominences 69
CHAPTER IV. FORMATION OF PROMINENCES 78
4.1. Condensations 78
4.2. Injections 89
4.3. Spicules 104
CHAPTER V. STABILITY OF PROMINENCES 107
5.1. Thermal Equilibrium - The Heating Problem 107
5.2. Dynamic Equilibrium - The Importance of Magnetic Fields III
5.3. The Disparition Brusque as an Instability 116
CHAPTER VI. INTERACTION OF PROMINENCES WITH CENTERS OF ACTIVITY
6.1. The Influence of Sunspots 119
6.2. PromInence Flare Interactions 121
6.3. Interaction of Prominences with Each Other 128
VIII SOLAR PROMINENCES
CHAPTER VII. PROMINENCES AS PART OF THE CORONA 131
7.1. Quiescent Prominences 131
7.2. Active and Activated Prominences 135
7.3. Miscellaneous 137
REFERENCES 140
INDEX OF NAMES 149
153
INDEX OF SUBJECTS
PREFACE
o
beaute sans seconde
SeuIe sembIabIe Ii toi
SOLEIL pour tout Ie monde ...
JEAN-FRANc;OIS SARASIN (1615-1654)
The last decade has seen the publication of monographs covering most areas of solar
activity: flares (Smith and Smith, 1963), sunspots (Bray and Loughhead, 1964) and
the corona (Billings, 1966). Consequently, of all the major manifestations of solar
activity only prominences are without a comprehensive and unified treatment in the
current literature.
The present book is written in an attempt to remedy this situation, and to furnish
an account of some of the most spectacular and most beautiful aspects of solar activity.
Our ultimate aim is an understanding of the physical processes involved. I hope that
this book may provide if only a small step toward this goal.
After an historical introduction and some general definitions Chapter I proceeds
with an account of several classification schemes for prominences. Most of the
observational material is presented in Chapter II and forms the basis on which
different models of prominences are built in Chapter III. Chapters IV and V give most
of the physics of prominences, treating, as they do, the formation and stability of these
objects. The interaction of prominences with other manifestations of solar activity
is the subject of Chapter VI, and the final Chapter VII considers prominences in the
larger context: as an integral part of the corona.
The book is intended for the advanced student in astrophysics who may want to
specialize in the fascinating field of solar activity. In addition, I hope that some of my
colleagues may find parts of the book helpful in their teaching and research.
It is a pleasure to acknowledge the valuable help of J. Goff in preparing photographs
for the figures, and of the Graphic Arts Department of NCAR for all the drawings.
Special thanks are due to Mrs R. Fu1k for her careful typing of the manuscript.
I have benefited greatly from discussions with many of my colleagues, to whom I
give my grateful thanks: R. G. Athay, A. Bruzek, R. T. Hansen, E. Hildner, T.
Hirayama, C. L. Hyder, Y. Nakagawa, R. Noyes, G. Pneuman, A. Poland, F. Q.
Orrall, E. Priest, and D. Smith.
Finally, I would like to express my appreciation to the astronomers who provided
me with some of the illustrations: Mrs S. F. Martin, R. Dunn, and G. Pneuman.
Boulder, Colorado, April 1973
LIST OF SYMBOLS AND PHYSICAL CONSTANTS
a ratio between collisional halfw idth and Doppler halfw idth
A Einstein coefficient; area; amplitude
b parameter expressing deviation from local thermodynamic equilibrium
B Einstein coefficient; magnetic field; Planck function
c velocity of light; specific heat
C collisional rate coefficient
d distance
D distance
e base of natural logarithm; electronic charge
E electric field; energy
f oscillator strength; distribution function
F flux
g gravitational acceleration; statistical weight; Gaunt factor; Lande's g factor
G constant of gravitation; energy gain function
h Planck's constant; height
H scale height; radiative flux
i imaginary unit (v-=i)
I Stokes parameter; specific intensity
j current density; emission coefficient
J mean intensity; Bessel function; action variable
k Boltzmann's constant; absorption coefficient; wave number
K degree absolute; thermal conductivity; restoring force
I characteristic length
L characteristic length; orbital angular momentum quantum number; energy loss
function
m mass
M mass; magnetic quantum number
n principal quantum number; number density of particles; refraction index; vector
normal
N number of particles in column of cross section 1 cm2
p pressure; momentum
P rate coefficient (P=R+C); probability; power; period = 21l/w; degree of
polarization
q heat flow
Q Stokes parameter; energy
r cylindrical polar coordinate; distance (radial); ratio of continuum absorption
coefficient to line absorption coefficient
XII SOLAR PROMINENCES
R gas constant; radiative rate coefficient; Reynolds' number
s entropy; coordinate along field line
S spin quantum number; source function; Poynting vector
t time
T temperature; stress tensor
u velocity
U partition function; heat energy; Stokes parameter
v flow velocity (macroscopic)
V gross velocity; wave velocity; volume; Stokes parameter
w particle velocity (microscopic)
W energy; geometrical dilution factor
x cartesian coordinate
X prominence thickness
y cartesian coordinate
z cartesian and cylindrical polar coordinate
Z atomic number
a filamentary structure ratio; coefficient of volume expansion; absorption coefficient
per atom; angle; reciprocal pitch
y ratio of specific heats; damping constant; angle; ratio between gas pressure and
magnetic pressure
~ delta function; angle
..dA. halfw idth of spectral line
emissivity; dielectric constant; energy density
8' complex dielectric constant (8' = e - i(4na/OJ))
coefficient of viscosity
angle
continuum quantum number
wavelength; mean free path
Au Larmor radius
J.l magnetic moment; mean molecular weight
frequency
microturbulent velocity
density; net radiative bracket
Stefan's constant; electric conductivity
optical depth; diffusion time
cylindrical polar coordinate; latitude; phase; absorption profile; scalar potential;
angle variable
cp magnetic flux; gravitational potential
X electric potential
circular frequency; angular velocity
OJ
Physical Constants
Boltzmann's constant k = 1·38 X 10-16 erg K-1
Electron rest mass me= 9·1 x 10-28 g