Solar Astrophysics 2nd ed - P. Foukal (Wiley-VCH, 2004) WW.pdf - Najnowsze ksiazki(15) - walbo48

Peter V. Foukal

Solar Astrophysics

Second, Revised Edition

WKEY-

VCH

WILEY-VCH Verlag CmbH & Co. KCaA

Author

This book was carefully produced. Nevertheless,

editors, authors and publisher do not warrant the

information contained therein to be free of errors.

Readers are advised to keep in mind that statements,

data, illustrations, procedural details or other items

may inadvertently be inaccurate.

Dr. Peter Y. Foukal

Heliophysics, Inc.

pfoukal@world.std.com

Library ofCongress Card No. applied for

British Library Cataloguingin-PublicationData

A catalogue record for this book is available from the

British Library.

Bibliographic information publishedby

Die Deutsche Bibliothek

Die Deutsche Bibliothek lists this publication in the

Deutsche Nationalbibliografie; detailed bibliographic

data is available in the Internet at

<http://dnb.ddb.de>.

Cover Picture The sunspots are part of NOAA

Active Region 10030 observed on 15 luly 2002 using

the Swedish 1-m Solar Telescope. Kindly provided

by G. Scharmer

0 2004 WILEY-VCH Verlag GmbH & Co. KGaA

Weinheim

into other languages). No part of this book may be

reproduced in any form - nor transmitted or trans-

lated into machine language without written permis-

sion from the publishers. Registered names, trade-

marks, etc. used in this book, even when not

specifically marked as such, are not to be considered

unprotected by law.

Printed in the Federal Republic of Germany.

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ISBN 3-527-40374-4

Kuhn 6r Weyh, Satz und Medien,

TO Lizzie

I “I‘

Preface to the Second Edition

Understanding of the sun has advanced in several important areas since the first

edition of this text in 1990. Nobel prize-winning neutrino measurements have con-

firmed recently that we really do understand how the sun and stars shine. Analyses

of solar irradiance measurements have shown how the luminosity of the sun and

similar stars is modulated by the surprisingly effective valve of photospheric mag-

netic activity. Helioseismic measurements of the sun’s radial temperature profile

now agree with the standard model of the solar interior to better than 95%. They

also reveal the sun’s internal rotation profile, showing an interesting shear layer

between the radiative core and convection zone, and confirming earlier evidence for

another, immediately below the photosphere.

Improved simulations of solar convection now reproduce photospheric granula-

tion remarkably well, with prediction of the larger observed supergranular convec-

tion scale as the next aim. When rotational influences are included, such models

can explain the tendency to angular momentum conservation that seems to be ob-

served in supergranular-scale overturning. This modest but encouraging success

may offer a clue toward more ambitious explanation of the sun’s deeper differential

rotation with latitude. Dynamo models based on flux transport by the observed

motions of the solar interior, including new evidence for a meridional circulation,

can reproduce increasingly detailed aspects of the solar magnetic cycle. But a

successful dynamical model remains a goal.

In the corona, new observations of dramaticallyanisotropic temperature distribu-

tions, and of large abundance anomalies relative to photospheric layers, encourage

new thinking about the mechanisms most likely to heat and accelerate the solar

wind. Measurements from the Ulysses spacecraft reveal the 3-D structure of the

heliosphere and indicate that the fast wind from coronal holes is the prevalent flow

except at low latitudes, and around solar activity maximum. New data from the

SOH0 mission and other spacecraft have helped to understand the important role

that coronal mass ejections (CME’s)play in geomagnetic disturbances and solar

energetic particle events (“spaceweather”).But key processes of e.g. solar cosmic ray

acceleration seem to originate within the flare site itself. The hottest plasmas around

the flare source are now being imaged spectrally in hard X-rays and gamma rays

from the RHESSI mission, and using radio frequency timing techniques.

The aim of this book remains the same - to provide an introductory but quantita-

tive discussion of solar phenomena and relevant astrophysical processes. The need

Solar Astrophysics. Peter V. Foukal

ISBN: 3-527-40374-4

I for this seems to increase as the research literature becomes ever more specialized

and challenging to assimilate (especially for veterans like the author!). Happily,

some obsolete material could be deleted, making room for those new developments

that seem most significant for this introductory account. The references have also

been updated, but some classics have been retained; they sometimes provide the

clearest explanations. Several new figures have been included to illustrate specific

advances in understanding, or without apology, simply to show readers spectacular

new images. Hannes Alfven was motivated by films of solar prominences to formu-

late his Nobel prize-winning theory of conducting fluid dynamics, and the beauty of

the sun’s magnetic structure always provides an attraction to solar research.

I am grateful to numerous colleagues for their advice on recent research develop-

ments- the opportunity to renew such contacts has provided one of the main satis-

factions of revising this text. I am particularly indebted to those who contributed

figures and tables, in some cases produced specifically for this book. Except in Chap-

ter 1, I emphasize results over techniques. This is not intended to overlook the debt

that solar research owes to the many skilled scientists who devote their careers to

development of sophisticated ground based and space-borne instrumentation. Some

detailed accounts of the interesting instruments,spacecraft and ground based facil-

ities used in solar observations are cited in references, particularly in Chaper 1.

Study of the sun has provided me with great personal enjoyment since 1969,when I

first arrived at CalTech to work as a post doctoral fellow with Hal Zirin. Previously, my

graduate research in galactic astronomy in Manchester, England with Z. Kopal and

J. Meaburn, had taken meto the Pic du Midi Observatory in the French Pyrenees,where

I was impressed by my first views of the sun - some through Bernard Lyot’s famous

coronagraph. Hal’s knowledge of the sun, and his generosity and enthusiasm provided

a supportive environment for my first optical and radio measurements of the sun.

An opportunity to move to Harvard in 1972 provided my first experience with (then

novel) “big”space science, through participation in the SkyLab mission. The Harvard

EUV data provided an exciting new window on the sun’s atmosphere, and I benefited

from many discussions on this topic, and on my other interests in solar rotation, lumin-

osity variation, and plasma electric field diagnostics, with Gene Avrett, Andrea Dupree,

David Layzer, Bob Noyes, and other CFA colleagues. A prominent visitor at Harvard at

that time was Jack Eddy, whose investigations of solar activity and climate records pro-

vided all of us with a new outlook on sun-climate studies. Jacksmentoring after I left

Harvard to continue my solar studies through private research firms, opened opportu-

nities for which I continue to be grateful.

My unusual career path in solar research would not have been possible without the

multiplicity and pragmatism of funding sources that is a great strength of US science.

Internationally, solar research continues to enjoy ample support for wonderful ground-

based and space-bornefacilities. Its futuredepends on attracting imaginative and skilled

young scientists to achievethe potential ofthese facilities. Ifthis book helps to interest a

few such individuals in solar research, it will have met its goal.

Peter Foukal

Nahant, Massachusetts

Vlll Preface

Solar Astrophysics 2nd ed - P. Foukal (Wiley-VCH, 2004) WW.pdf

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