Physics of Meteoric Phenomena

372 Pages·1983·28.985 MB·English

by  V. A. Bronshten (auth.)

PHYSICS OF METEORIC PHENOMENA
GEOPHYSICS AND
ASTROPHYSICS MONOGRAPHS
Editor
B.M. MCCoRMAC, Lockheed Palo Alto Research Laboratory, Palo Alto, Cali/., U.S.A.
Editorial Board
R. GRANT AmAY, High Altitude Observatory, Boulder, Colo., U.S.A.
W.S. BROECKER, Lamont-Doherty Geological Observatory, Palisades, New York, U.S.A.
P.J. CoLEMAN, JR., University o/Cali/ornia, Los Angeles, Cali/., U.S.A.
G.T. CSANADY, Woods Hole Oceanographic Institution, Woods Hole, Mass., U.S.A.
D.M. HUNTEN, University 0/ Arizona, Tucson, Ariz., U.S.A.
C. DE JAGER, The Astronomical Institute, Utrecht, The Netherlands
J. KLECZEK, Czechoslovak Academy 0/ Science, OndFejov, Czechoslovakia
R. LUST, President Max-Planck Gesellscha/t/iir Forderung der Wissenscha/ten, Miinchen, F.R.G.
R~E.. ¥ul)IN, Vn4ve~fP)l pI tot;onto, T~~l!nto, Ont., Canada
Z. SVESTKA, The Astronomical Institute, Uirecht, The Netherlands
G. WEILL., Service d'Aeronomie, Verrieres-le-Buisson, France
V.A.BRONSHTEN
Central Council of the All-Union Astronomical-Geodetic Society (U.S.S.R.)
PHYSICS OF
METEORIC PHENOMENA
....
D. REIDEL PUBLISHING COMPANY
A MEMBER OF THE KLUWER " ACADEMIC PUBLISHERS GROUP
DORDRECHT/BOSTONjLANCASTER
library of Congress Cataloging in Publication Data
Bronshten, Vitalij Aleksandrovich.
Physics of meteoric phenomena.
(Geophysics and astrophysics monographs)
Translation of Fizika meteornykh iavlenii.
Includes bibliographical references and index.
1. Meteors. I. Title. II. Series.
QB741.B8813 1983 523.5'1 83-15981
ISBN-13: 978-94-009-7224-7 e-ISBN-13: 978-94-009-7222-3
DOl: 10.\007/978-94-009-7222-3
Published by D. Reidel Publishing Company,
P.O. Box 17,3300 AA Dordrecht, Holland.
Sold and distributed in the U.S.A. and Canada
by Kluwer Academic Publishers,
190 Old Derby Street, Hingham, MA 02043, U.S.A.
In all other countries, sold and distributed
by Kluwer Academic Publishers Group,
P.O. Box 322, 3300 AH Dordrecht, Holland.
All Rights Reserved
© 1983 by D. Reidel Publishing Company, Dordrecht, Holland
Original © 1981 Nauka
Translated from the Russian by UAT Ltd.
Softcover reprint of the hardcover I st edition 1983
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical
including photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner
TABLE OF CONTENTS
PREFACE IX
PREFACE TO THE ENGLISH EDITION XIII
GLOSSARY XV
INTRODUCTION
l. General Information about Meteoric Phenomena 1
2. Historical Review of Research in Meteor Physics 3
CHAPTER I. THE SIMPLE PHYSICAL THEORY OF METEORS
3. Fundamental Equations 12
4. Self-Similarity of the Problem of Motion
and Ablation of a Meteoroid 17
5. The Problem of Meteoroid Motion with
Variable Coefficients 24
6. Flow Regimes 29
7. Parameters of the Fundamental Equations 36
CHAPTER II. THE HEATING OF METEOROIDS AND THE ONSET
OF VAPORIZATION
8. The Heating of a Meteoroid in the Upper
Section of its Path 52
9. The Transition to Intensive Evaporation 58
10. Shielding Effects. The Regime of First
Collisions 66
1l. Shielding in the Transition Regime 75
12. The Case of Strong Shielding 86
CHAPTER III. ABLATION OF METEOROIDS
13. Two Main Mechanisms of Ablation: Vaporization
and Spraying or Blowoff of the Molten Layer 91
14. Experimental Studies of Ablation 100
15. Theoretical Studies of the Ablation of
Large Bodies 105
16. Large-Meteoroid Vaporization under the
Influence of the Radiation Flux 115
V
VI PHYSICS OF METEORIC PHENOMENA
17. Formation of an Ablational Shock Wave and
the Energetics of Large Meteoroids 122
18. Ablation and Meteorite Morphology 133
CHAPTER IV. LUMINOSITIES AND SPECTRA OF METEORS
19. The Nature of Meteor Radiation 139
20. The Luminosity Equation and its Parameters 146
21. Experimental Determinations of the Radiative
Efficiency 156
22. The Effect of Meteoroid Flight Condition
on the Radiative Efficiency 159
23. The Qualitative Analysis of Meteor Spectra 165
24. The Quantitative Analysis of Meteor Spectra.
The Curve-of-Growth Method 175
25. Determination of the Chemical Compositions
of Meteoroids from their Spectra. Comparison
with Meteorites 189
26. Some Unusual Emissions 194
CHAPTER V. METEORIC IONIZATION
27. Formation of the Ion Trail 209
28. Classification of Meteor Ion Trails 219
29. Disintegration of the Ion Trail 225
30. The Head Echo and its Relation to
other Phenomena 233
CHAPTER VI. MASSES AND DENSITIES OF METEOROIDS
31. Dynamic Masses 236
32. Photometric Masses 238
33. The Hypothesis of Dustballs and
Friable Meteoric Bodies 243
34. Explanation of the "Mass Paradox" as an Effect
of Fragmentation 247
35. Determination of the Mineralogical
Densities of the Meteoroids 252
36. Determination of the Densities of
Large Meteoroids from their Breakup Heights 256
CHAPTER VII. FRAGMENTATION OF METEOROIDS
37. Observational Data on Meteoroid
Fragmentation 265
38. Effect of Fragmentation on the
Photometric Curve 272
39. Meteor Bursts 277
40. Fragmentation of Meteorites 280
41. Physical Aspects of Meteoroid Fragmentation 284
TABLE OF CONTENTS VII
APPENDIXES TO THE ENGLISH EDITIONS
1. A Quasi-Simple Ablation Model for the Entry of
Large Meteoroids into the Atmosphere 295
2. Transfer of the Shock-Wave Radiation to the
Body of the Meteoroid 297
3. Electrophonic Phenomena during the
Flight of a Bright Bolide 299
4. The Dynamics of Meteoroid Breakup 301
REFERENCES FOR APPENDIXES 305
REFERENCES 307
INDEX 343
PREFACE
"Meteoric phenomena" is the accepted term for the complex of physi
cal phenomena that accompany the entry of meteoric bodies into the at
mosphere of the earth (or of any planet). "Meteoric bodies" are usually
defined as cosmic bodies observed by optical or radar techniques, when
they enter the atmosphere. The limiting sensitivity of present-day radar
equipment makes it possible to record meteors of up to stellar magnitude
+14, while the most brilliant bolides may reach magnitude -19. On a mass
scale this corresponds approximately to a range of 10-7 to 107 g. How
ever, met~or astronomy is also concerned with larger objects, namely
crater-forming meteorites, or objects that cause large-scale destruction
when they arrive through the atmosphere (an example is the Tunguska
River meteorite). Consideration of the interaction of such objects with
the terrestrial atmosphere extends the mass range to 1012 g. On the
other hand, scientists studying fragmentation processes in meteoric bod
ies have to consider particles with masses less than 10-7 g, and the use
of data from meteoric-particle counters on rockets and artificial satel
lites, from microcraters on the lunar surface, and from noctilucent clouds
lowers the minimum mass to 10-12 g. Therefore, the mass range of meteoric
bodies, or meteoroids, encompasses 24 orders of magnitude.
Although recent years have witnessed considerable development in
meteor research, both in the Soviet Union and elsewhere, the main mono
graphs on meteor physics were published twenty or more years ago. These
are B.Yu. Levin's "The Physical Theory of Meteors and Meteoric Matter in
the Solar System" (Moscow, 1956) [147], and E.J. Opik's "Physics of
Meteor Flight in the Atmosphere" (New York, 1958) [428], both of which
served as textbooks for many of today's meteor scientists. Since then,
however, much new research has been carried out, new observational and
experimental techniques have been developed, and the theory of meteoric
phenomena has not lagged far behind.
Of other monographs devoted to the study of meteors, we should
mention, first and foremost, loS. Astapovich's "Meteoric Phenomena in
the Earth's Atmosphere" (Moscow, 1958) [8]. This book, however, is only
an extensive compendium of the results of meteor observations by diff
erent methods, from the very beginning of the scientific study of meteors
to the mid-fifties of this century. As far as the volume of factual mat
erial is concerned, Astapovich's work may be considered unsurpassed even
today; the theory of meteors, however, is accorded very little attention
in his book.
Two books by L.A. Katasev, "Photographic Methods of Meteor Astron
omy" (Moscow, 1957) [92] and "The Study of Meteors in the Earth's Atmo-
sphere by the Photographic Method" (Leningrad, 1966) [93], betray by
IX
x PREFACE
their titles that they are concerned solely with the techniques and
results of photographic investigations of meteors, though the second
book does give an account of a few theoretical problems.
Almost the same is true of D.W.R. McKinley's book "Meteor Science
and Engineering" (New York, 1961) [393], translated into Russian as
"Methods of Meteor Astronomy" (Moscow, 1964). In this workm the emphasis
is placed on investigative techniques, although numerous results of
meteor observations using optical and radar techniques are also presen
ted. One chapter is devoted to the theory of meteoric phenomena.
A very good exposition of the foundations of the physical theory
of meteors is provided by B.L. Kashcheev, V.N. Lebedinets, and M.F.
Lagutin, in "Meteoric Phenomena in the Earth's Atmosphere" (Moscow,
1967) [98], one of a series of publications by the Interdepartmental
Geophysics Committee. However, as pointed out by the authors themselves,
this book treats the physical theory of meteors as applied to radar
techniques, focusing attention on the vaporization of small meteoric
bodies and on the formation and disintegration of meteoric ion trails.
The lack of an up-to-date book reflecting the present state of the
art in meteor physics set the author the difficult task of summarizing
the results of research in this area over the last 20 years. In the
process, it turned out that many investigators dealing with problems
in the interaction of meteoric bodies with the atmosphere have made in
sufficient use of advances in gas dynamics, aerodynamics, and plasma
physics. Conversely, specialists in these fields appeal not infrequently
to meteoric phenomena, but they do not have at their disposal all the
necessary knowledge from meteor physics and - above all - observational
results, a situation which occasionally gives rise to unfortunate mis
understandings. Out of a desire to use advances in gas dynamics and
plasma physics for a better understanding of meteoric phenomena, the
author was induced to pay particular attention to this aspect of the
problem.
This desire has also conditioned the structure of the book. In the
introduction we present the fundamental definitions and provide a brief
historical survey of research in meteor physics. Chapter I is an expo
sition of the simple physical theory of meteors; the fundamental equa
tions are presented and solved for constant and variable coefficients.
Also considered in this chapter is the elasticity of the interaction of
air particles with a meteoric body and the regimes of flow of the on
coming air stream around the body. In Chapter II we consider the heating
of the meteoroid when it enters the atmosphere, the onset of intensive
vaporization, and effects due to shielding of the meteoroid by
reflected and evaporating molecules. Chapter III is devoted to ablation
processes. Chapter IV considers the luminosity and spectra of meteors,
and Chapter V discusses meteoric ionization. Chapter VI deals with
methods for determining the mass and density of a meteoroid, and the
findings made with these methods. Finally, Chapter VII considers
different types of fragmentation.
Throughout the exposition of these problems, the author has striven
to emphasize the physical aspect of the phenomenon. Significantly more
attention than hitherto has been given to the emission spectra of meteors
and their interpretation, to bursts, and to mechanism of meteor fragment-
PREFACE XI
ation.
When dealing with questions related to gas dynamics and plasma
physics, we have inevitably had to use the accepted terminology of these
fields. Whenever necessary, specialized terms have been explained in
footnotes.
The author deems it his duty to mention that the idea of writing
this monograph, and the plan of the book, were approved by the late
V.V. Fedynskii, Associate Member of the Soviet Academy of Sciences,
whose remarks proved to be most useful while the book was being written.
Fedynskii played a major role in the organization of meteor research in
the USSR; he was involved in visual work in the twenties of this century,
in photographic studies during the thirties and forties, and in radar
studies during the past three decades.
Finally, the author is deeply indebted to S.S. Grigoryan, V.N.
Lebedinets, B.Yu. Levin, and K.P. Stanyukovich for their attentive
perusal of the book in manuscript and for their useful comments.
V.A. Bronshten