Table Of ContentATLAS AND CATALOGUE
OF INFRARED SOURCES IN THE MAGELLANIC CLOUDS
ATLAS AND CATALOGUE
OF INFRARED SOURCES
IN THE MAGELLANIC CLOUDS
by
P. B. W. Schwering and F. P. Israel
Sterrewacht Leiden, The Netherlands
KLUWER ACADEMIC PUBLISHERS
DORDRECHT / BOSTON / LONDON
Ubrary of Congress Cataloging in Publication Data
Schwering, P. B. W.
Atlas and catalogue of infrared sources in the Magellanic Clouds /
by P.B.W. Schwering and F.P. Israel.
p. en;.
Includes bibliographical references.
1. Magellanie Clouds--Atlases. 2. Magellanie Clouds--Catalogs.
3. Infrared sourees--Atlases. 4. Infrared sources--Catalogs.
5. Infrared astronomy--Atlases. 6. Infrared astronorny--Catalogs.
1. Israel, F. P. II. Title.
QB858.5.M33S38 1990
522' .68--dc20 89-71712
ISBN-13: 978-94-010-6728-7 e-ISBN-13: 978-94-009-0537-5
DOl: 10.1007/978-94-009-0537-5
Published by Kluwer Academic Publishers,
P.O. Box 17, 3300 AA Dordrecht, The Netherlands.
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© 1990 by Kluwer Academic Publishers
Softcover reprint of the hardcover 1s t edition 1990
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.
The Atlas and Catalogue of infrared sources in the Magellanic Clouds was prepared
from data obtained with the Infrared Astronomical Satellite (IRAS). IRAS was developed
and operated by the Netherlands Agency for Aerospace Programs (NIVR) , the U.S.
National Aeronautics and Space Administration (NASA) and the U.K. Science and
Engineering Research Council (SERe).
TABLE OF CONTENTS
1. Introduction . 1
2. Infrared Source Identification Tables 7
Table SMC-2.1: Ha Nebulae 11
SMC-2.2: Dark Clouds 15
SMC-2.3: Stellar Objects 16
LMC-2.1: Ha Nebulae 17
LMC-2.2: Dark Clouds 27
LMC-2.3: Stellar Objects 29
3. The Leiden-IRAS Magellanic Clouds Infrared Source Catalogues 33
Catalogue LI-SMC 38
Catalogue LI-LMC 46
4. Atlas of Infrared Emission of the Magellanic Clouds 103
Table SMC-4.1: Fields 106
LMC-4.1: Fields 107
SMC-4.2: Field Characteristics 108
LMC-4.2: Field Characteristics 109
SMC-4.3: Atlas Contour levels 110
LMC-4.3: Atlas Contour levels 111
Atlas SMC 112
Atlas LMC 134
INTRODUCTION
1. Introduction
Around the beginning of the sixteenth century, Portuguese and Dutch sailors first
ventured into southern seas. With their keen navigational interest in the skies, they noted
almost immediately the continuous presence of two cloud-like features, not far from the
Southern Pole. The first literature mention of these 'clouds' was in the journal written
in 1520 by the Italian navigator Pigafetta on the first circumnavigation of the globe by
Magalhaes (c/. Pigafetta et ai., 1962). In honour of this exploit, the objects have since
become known as the Magellanic Clouds, although the Dutch name 'Kaapsche Wolken'
(Cape Clouds - after the Cape of Good Hope) has also been in use for centuries.
The Large and Small Magellanic Clouds are dwarf irregular galaxies, orbiting our
own Milky Way Galaxy, presently at distances of 53 and 63 kpc respectively (Humphreys,
1984) .. They are the galaxies nearest to us: most other Local Group galaxies are of order
ten times more distant. The LMC and SMC are also the prototypical blue dwarf irregulars,
representatives of a class of objects in which several hundred more distant objects are now
known. Their masses are a few per cent of the mass of the Milky Way Galaxy, but they
are relatively gas-rich and appear to be, at the present epoch, forming stars at a more
prodiguous rate than our Galaxy (c/. Lequeux, 1984). Compared to the Galaxy, they
are poor in heavy elements (Dufour, 1984), poor in dust (Koornneef, 1984), and have a
relatively weak CO signature (Israel, 1984), often taken as representative for the total
abundance of molecular material (mainly H2). In these aspects, they are similar to other
blue dwarf irregulars, but different from larger spiral galaxies.
It has been difficult to quantify the dust and molecular contents of the Magellanic
Clouds. Molecular measurements are only now being carried out on a significant scale with
the facilities of the European Southern Observatory. In the past, several attempts have
been made to gauge the dust content of the Clouds by absorption and extinction studies.
These studies yielded important qualitative conclusions, but failed to produce a clear
quantitative result (cf. Israel, 1984; Koornneef, 1984). Yet, this is a matter of importance,
as dust and molecular abundances provide clues to the evolution of the Clouds. Details
of dust and molecular distribution and properties also provide important clues to ongoing
physical process in the Clouds, including the formation of stars. A fuller, more quantitative
understanding of dust and molecular properties of the Magellanic Clouds transcends that
4 INTRODUCTION
of Cloud studies alone. The proximity of the Clouds allows analysis of the interrelation
between detailed and global characteristics. In turn, this is essential to the interpretation
of measurements of more distant galaxies, where only global (integrated) properties can
be determined.
A more fruitful approach to the question of the dust content of the Magellanic Clouds is
the measurement of thermal emission from dust particles. With the expected temperature
range (15 to 1500 K), this emission will primarily take place at infrared and submillimeter
wavelengths (10 microns to 1 millimeter). Prior to 1983, few such measurements existed,
especially at wavelengths beyond 10 microns where the bulk of emission was to be expected.
Characteristically, the all-sky AFGL rocket survey (Price and Walker, 1976) yielded
only four 20 micron sources in the LMC and none in the SMC. Succesful observations
from atmospheric platforms were limited to a few sources (see Schwering, 1988, p. 12).
This situation changed dramatically with the succesful IRAS mission in 1983 (IRAS, 1989).
The all-sky survey, as well as the additional (pointed) observations, covered the Magellanic
Clouds several times, and yielded fully sampled data at wavelengths of 12, 25, 60 and 100
mIcrons.
The IRAS data have been used to construct maps of the infrared emission of the
Magellanic Clouds at these wavelengths (Schwering, 1988; Rice et al., 1988; see also
Schwering and Israel, 1989; Schwering 1989). The maps presented here are based on
observations obtained in the Additional Observations (AO) program, in the Deep Sky
Mapping (DPM) mode. In this mode, a raster scan of 6 or 7 legs of 166 arc min in length
was made with a cross-scan step of 20 arcmin. Scanning was performed in the survey
direction at a rate of 3.85 arc min per second. The proximity of the Clouds to the Southern
Galactic Pole made it possible to obtain sets of observations with almost orthogonal scan
directions (approximately East-West and North-South). Because of the rectangular form
of the IRAS detectors, resolution in the in-scan direction is considerably higher than in the
cross-scan direction. The two datasets therefore provide maps with maximum resolution
in both directions. We have chosen to present both map sets independently. In principle,
it is possible to combine the orthogonal sets into full resolution maps. However, because of
the non-uniform response of the IRAS detectors, the only correct way of doing this is by
'cleaning' individual detector 'streams' before combining them into a map, at a considerable
cost in computer time. Attempts to combine orthogonal maps and then cleaning them in all
INTRODUCTION 5
cases created sidelobe effects and other artifacts that could not be removed satisfactorily.
We therefore decided not to include those.
The main body of this publication is the Infrared Atlas of the Magellanic Clouds
contained in Part 4 and the Catalogue of Infrared Sources contained in these maps in Part
3. Preceding the Atlas and Catalogue is a set of Tables correlating Catalogue sources
with objects listed in other (optical) catalogues (Part 2). A series of transparent overlays
facilitates identification of Catalogue sources in Atlas maps.
The purpose of this publication is to supply the IRAS infrared maps and infrared
source lists, as well as source identifications in a form convenient for other workers on
Magellanic Cloud studies. For a discussion of the IRAS data on the Magellanic Clouds,
the reader is referred to Schwering (1988) and subsequent publications in journals such as
Astronomy and Astrophysics.
References
Dufour, J.: 1984, in "Structure and Evolution of the Magellanic Clouds", IAU Symposium
108, eds. S. van den Bergh and K.S. de Boer, Reidel Publ. Co, Dordrecht, p. 353
Humphreys, R.M.: 1984, in "Structure and Evolution of the Magellanic Clouds", IAU
Symposium lOS, eds. S. van den Bergh and K.S. de Boer, Reidel Publ. Co, Dordrecht,
p. 145
IRAS: 19S9, Infrared Astronomical Satellite (IRAS) Catalogs and Atlases, Volume 1,
Explanatory Supplement, eds. C.A. Beichman, G. Neugebauer, H.J. Habing, P.E. Clegg
and T.J. Chester, NASA RP-1l90, Washington, DC (USA)
Israel, F.P.: 19S4, in "Structure and Evolution of the Magellanic Clouds", IAU Symposium
108, eds. S. van den Bergh and K.S. de Boer, Reidel Publ. Co, Dordrecht, p. 319
Lequeux, J.: 1984, in "Structure and Evolution of the Magellanic Clouds", IAU Symposium
108, eds. S. van den Bergh and K.S. de Boer, Reidel Publ. Co, Dordrecht, p. 67
Koornneef, J.: 1984, in "Structure and Evolution of the Magellanic Clouds", IAU
Symposium 108, eds. S. van den Bergh and K.S. de Boer, Reidel Publ. Co, Dordrecht,
p.333
6 INTRODUCTION
Pigafetta, A., Transylvania, M. of, Correa, G.: 1962, "Magellan's Voyage around the
World", ed. C.E. Nowell, Northwestern Univ. Press, Evanston, p. 127
Price, S.D., Walker, R.G., 1976, "The AFGL Four Color Infrared Sky Survey: Catalog of
Observations at 4.2, 11.0, 19.8 and 27.4 JLm", AFGL-TR-76-0208, USAF Geophys.
Lab., Hanscomb AFB, Mass. (USA)
Rice, W., Lonsdale, R.J., Soifer, B.T., Neugebauer, G., Kopan, E.L., Lloyd, L.A., de Jong,
T., Habing, H.J.: 1988, Astrophys. J. Suppl. 68,91
Schwering, P.B.W.: 1988, Ph.D. Thesis, University of Leiden (NL)
Schwering, P.B. W., Israel, F .P.: 1989, Astron. Astrophys. Suppl. 79, 79
Schwering, P.B.W.: 1989, Astron. Astrophys. Suppl. 79, 105
