Table Of ContentRADIO RECOMBINATION LINES: 25 YEARS OF INVESTIGATION
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 of Utrecht, The Netherlands
J. KLECZEK, Czechoslovak Academy of Sciences, Ondfejov, Czechoslavakia
Z. KOPAL, University of Manchester, England
R. LUST, European Space Agency, Paris, France
L. I. SEDOV, Academy of Sciences of the U.S.S.R., Moscow, U.S.S.R.
Z. SvESTKA, Laboratory for Space Research, Utrecht, The Netherlands
PROCEEDINGS
VOLUME 163
RADIO
RECOMBINATION LINES:
25 YEARS
OF INVESTIGATION
PROCEEDINGS OF THE 125TH COLLOQUIUM OF THE
INTERNATIONAL ASTRONOMICAL UNION,
HELD IN PUSCHINO, U.S.S.R., SEPTEMBER 11-16, 1989
Edited by
M. A. GORDON
National Radio Astronomy Observatory, Tucson, Arizona, U.S.A.
and
R. L. SOROCHENKO
P. N. Lebedev Physical Institute, U.S.S.R. Academy of Sciences,
Moscow, U.S.S.R.
KLUWER ACADEMIC PUBLISHERS
DORDRECHT / BOSTON / LONDON
Library of Congress Cataloging in Publication Data
InternatIonal AstronomIcal UnIon. Colloquium (125th 1989
Pushchlno, Moscow, R.S.F.S.R.)
RadIo recombination lInes 25 years of investigation
proceedings of the 125th Colloquium of the International
AstronomIcal Union, held In Puschlno, U.S.S.R., September 11-16,
1989 I edited by M.A. Gordon, R.L. Sorochenko.
p. cm. -- (AstrophysIcs and space science 1 ibrary ; v. 163)
Includes bib110graphlcal references and indexes.
1. Radio recombInatIon llnes--Congresses. I. Gordon, M. A. (Mark
A.), 1937- II. Sorochenko, R. L. III. Title. IV. SerIes.
OB462.5.156 1989
522' .682--dc20 90-4713
ISBN-13: 978-94-010-6768-3 e-ISBN-13: 978-94-009-0625-9
DOl: 10.1007/978-94-009-0625-9
Published by Kluwer Academic Publishers,
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TABLE OF CONTENTS
Foreword ........................................................................... ix
List of Participants ................................................................. xi
GENERAL REVIEWS
Postulation, Detection, and Observations of Radio Recombination Lines
R. L. Sorochenko ............................................................. 1
Cavity Quantum Electrodynamics: Rydberg Atoms in Atomic Physics and Quantum
Optics
G. Rempe 8 H. vValther ..................................................... 19
THEORY OF RADIO RECOMBINATION LINES
Review of the Populations of Highly-Excited States of Atoms in Low Density Plasmas
S. A. Gulyaev ............................................................... 37
The Broadening of Radio Recombination Lines by Ion Collisions: New Theoretical
Results
D. Hoang-Binh .............................................................. 51
RADIO RECOMBINATION LINES FROM HII REGIONS
High Resolution Radio Recombination Line Observations
P. R. RoelJsema ............................................................. 59
Radio Recombination Lines from Compact HII Regions
G. Gamy .................................................................... 73
Radio Recombination Line Emission from Ultra-Compact HII Regions
E. Churchwell, C. M. Walmsley, D. O. S. Wood, 8 H. Steppe ................ 83
Radio Recombination Lines at Millimeter Wavelengths in HII Regions
M. A. Gordon ............................................................... 93
Maps of the 64a Radio Recombination Lines in Orion A
T. L. Wilson 8 L. Filges ................................................... 105
Estimate of Electron Densities in HII Regions from Observations of Pairs of a-Type
Recombination Radio Lines
A. F. Dmvskikh 8 Z. V. Dmvskikh ......................................... 115
Interferometric Observations of HII, CII, and HO Regions in Orion B
K. R. Ananthammaiah, W. M. Goss, 8 P. E. Dewdney ..................... 123
The Helium Abundance in the HII Region DR21
A. P. Tsivilev .............................................................. 131
vi
RRLs FROM PLANETARY NEBULAE AND STELLAR ENVELOPES
Radio Recombination Lines from Stellar Envelopes: Planetary Nebulae
Y. Terzian ................................................................. 141
Radio Recombination Lines from Compact Planetary Nebulae
G. Garay ................................................................... 155
Radio Recombination Line Maser Emission in MWC349
J. Martin-Pintado, R. Bachiller, f3 C. Thum ................................ 161
Recombination Emission from CIl-Regions Around Be-Stars
S. P. Tarafdar f3 I<. M. V. Apparao ............. '. . . . . . . . . . . . . . . . . . . . . . . . . .. 169
LOW FREQUENCY RECOMBINATION LINES
Review of Decameter Wave Recombination Lines: Problems and Methods
A. A. Konovalenko ......................................................... 175
Low Frequency Radio Recombination Lines Towards Cas A
R. L. Sorochenko f3 G. T. Smirnov ......................................... 189
Interferometric Observations of Carbon Recombination Lines Towards Cassiopeia A at
332 MHz
H. E. Payne, I<. R. Anantharamaiah, f3 W. C. Erickson .................... 203
Detection of Carbon Recombination Lines at Decameter Wavelengths in Some Galactic
Objects
A. A. Golynkin f3 A. A. Konovalenko ....................................... 209
RRLs from the Local Interstellar Medium
N. G. Bochkarev ............................................................ 219
LARGE-SCALE PROPERTIES OF THE GALAXY
Recombination Lines and Galactic Structure
F. J. Lockman .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 225
Study of the H166a Recombination Line in the Southern Milky Way
J. C. Cersosimo ............................................................ 237
Radio Recombination Line Imaging of Sgr A
W. M. Goss, J. H. van Gorkom, D. A. Roberts, f3 J. P. Leahy .............. 249
Limits of the Temperature and Filling Factor of the Warm Ionized Medium Towards the
Galactic Centre
K. R. Anantharamaiah, H. E. Payne, f3 D. Bhattacharya ................... 259
RADIO RECOMBINATION LINES FROM EXTRAGALACTIC OBJECTS
VLA Observations of Recombination Lines from the Star Burst Galaxy NGC253
K. R. Anantharamaiah f3 W. M. Goss ...................................... 267
vii
CONCLUSION OF THE COLLOQUIUM
Radio Recombination Lines at 25
P. A. Shaoer ............................................................... 277
INDEXES
Author ............................................................................ 285
Citation ........................................................................... 287
Subject ........................................................................... 295
FOREWORD
The year 1989 was the 25th anniversary of the astronomical detection of radio lines from
highly excited atoms. In the years following, these lines-known as Radio Recombination
Lines (RRLs )-have become a powerful tool to astronomers for distinguishing thermal
sources from nonthermal ones, for studying star formation regions, for investigating the
diffuse interstellar medium, and for exploring galactic structure.
This book contains the proceedings of the IAU Colloquium 125, focussed on the 25 years
of astronomical research with RRLs since their discovery in 1965. The colloquium was held
on September 12-14, 1990 in Puschino, USSR-a research station of the USSR Academy
of Sciences located about 100 km south of Moscow on the banks of the Oka river.
For many of us this was an historic occasion. First, it was an opportunity to meet people
whom we had come to know only by name in the scientific literature. Second, it was an
opportunity to appreciate the enormous scope of RRL astronomical research over the last
25 years. And, third, it was an opportunity to remind ourselves that RRL research also
involves research into the fundamental physics of atoms and not just astronomy.
The Colloquium covered a wide range of topics. This book contains papers dealing with
research into Rydberg atoms both in the laboratory and in the interstellar medium of our
galaxy and others. It contains papers dealing with the interaction of radiation and atomic
systems, as well as with the effects of inadiabatic collisons between these atoms and both
ions and electrons. It deals with astronomical observations of atoms with "diameters"
ranging from 0.081lm to 50llm-a factor of 625 in size. It deals with RRLs in absorption,
in emission, and as true masers. And, it deals with plasmas with temperatures ranging
from 10 to greater than 104 Kelvins, and with an even larger range of volume densities.
Although in some respects a sequel to the Ottawa Workshop on RRLs held on August
24-25,1979, this meeting involved a much larger number of people representing many coun
tries. Additionally, it dealt with the exciting new topics of low frequency RRLs discovered
in 1980 and of the maser RRLs from the star MWC349 discovered in 1989. The advent of
aperture synthesis telescopes and large single-element telescopes are now making possible
RRL studies with high angular resolution, studies which will enhance the wonderful results
already in hand. Our hope is that the papers in this volume will serve as a platform from
which to search new horizons in RRL research.
For this meeting the Scientific Organizing Committee consisted ofK. R. Anantharamaiah
(India), J. Caswell (Australia), M. A. Gordon (USA), W. M. Goss (USA), D. Hoang-Binh
(France), P. G. Mezger (FRG), P. A. Shaver (FRG), and R. L. Sorochenko (USSR). Shaver
and Sorochenko served as Co-Chairmen.
We thank the Scientific Organizing Committee and the meeting participants for an
excellent program, the Local Organizing Committee for a well-organized meeting, Jolanda
Karada of Kluwer Academic Publishers for help with publication, and the USSR Academy
of Sciences and the International Astronomical Union for their financial support.
M. A. Gordon R. L. Sorochenko
National Radio Astronomy Observatory P. N. Lebedev Physical Institute
Tucson, Arizona, USA USSR Academy of Sciences
Moscow, USSR
ix
LIST OF PARTICIPANTS
Argentina Golynkin, A. A.
Cersosimo, J. T. Gulyaev, S. A.
Dagkesamanskij, R. D.
Chile Draviskikh, A. F.
Garay, G. Ershov, A. A.
Kardeshev, N. S.
Federal Republic of Germany Konovalenko, A. A.
Rempe, G. Lekht, E. E.
Shaver, P. A. Losinkaja, T. A.
Walmsley, C. M. Malafeev, V. A.
Wilson, T. L. Ponomarenko, N. I.
Smirnov, G. T.
:France Sorochenko, R. L.
Hoang-Binh, D. Stepkin, S. V.
Shmeld, I.
India Strelnizkij, V. S.
Anantharamaiah, K. R. Tsivilev, A. P.
Qaiyum, A. Waltz, I. A.
Shankar, R.
Tarafdar, S. P.
Netherlands
Roelfsema, P. R.
Spain
Martin-Pintado, J.
USA
Chaisson, E. J.
Churchwell, E. B.
Gordon, M. A.
Goss, W. M.
Lockman, F. J.
Payne, H. E.
Terzian, Y.
Wood, D. O. S.
USSR
Abramenkov, E. A.
Avedisova, V.
Beigman, I. L.
Bochkarev, N. G.
Berulis, I. I.
xi
POSTUI.ATION, DETECTION AND OBSERVATIONS OF RADIO RECOMBINATION LINES
(REVIEW)
R. L. SOROCHENKO
Lebedev Physical Institute of the USSR Academy of Sciences
Moscow, Leninsky Prospect 53
USSR
ABSTRACT. Radio recombination lines (RRLl detected 25 years ago are'"
investigated in a wide, from mm to dam, range of wavelengths It has c"",'
cleared out that in Galaxy conditions an atom as a quantum system may
exist wi th exci taUon level n of up to 1000 reaching the giant size of
O. 1mm. RRL proved to be a new powerful tool for astrophysical research.
1.PREDICTION AND DETECTION OF RADIO RECOMBINATION LINES
Alomic speclral radiation caused by transitions between levels with
different principal quantum numbers (n) was detected about 100 years
ago. The I ines were the well known Lyman, Balmer' and Paschen I ine series
emitted by hydrogen in UV, visible and IR ranges. From this obser'vations
Bohr (1913) developed his quantum theory of atom, in which the spectral
lines' frequencies are defined by
v = R (1/n2 - 1/n2 ) s 2R 6n/n3 (if n»l) (1)
1 2
where nand n - are the principal quantum numbers of upper and lower
levels r~spectiv~ly, 6n=n -n , and R is Rydberg's constant (for hydrogen
R=3.288057*1015Hz). 2 1
Bohr's theory explained the observed series as transitions to the
first three atomic levels (n =1,2,3), and it predicted new lines.
Although it did not restricti the number of atomic levels nor"
number of line series, the theory gave no indication of how many se,'I("
could be detected in practice. Progress of experimenlal studies towards
the longer wavelength was very slow. The fourth series, the Bracket
series (A =4.05flm) was detected nine years after Bohr's theory had ap
peared; tfie4fifth series, the Pfundt (A =7.46flm) after 11 years; and
the sixth with A =12.3 flm, only aft~r5 40 years, as a result of
minute spectrum meas~r~ments of gas discharge (Humphfrey. 1953).
With these measurements the classical laboratory spectroscopy ran
out of abilities. Only new research technique could find new series.
Here is a situation where astronomy can not only solve a pr'oblem in
physics but gain a new field of astronomical research at the same time.
M. A. Gordon and R. L. Sorochenko (eds.), Radio Recombination Lines: 25 Years ofI nvestigation, 1-17.
© 1990 Kluwer Academic Publishers.
