The Messier Objects

Warren H. Finlay Concise Catalog of Deep-Sky Objects Astrophysical Information for 550 Galaxies, Clusters and Nebulae Second Edition The Patrick Moore The Patrick Moore Practical Astronomy Series For further volumes: http://www.springer.com/series/3192 Concise Catalog of Deep-Sky Objects Astrophysical Information for 550 Galaxies, Clusters and Nebulae Warren H. Finlay Second Edition Warren H. Finlay Edmonton , AB , Canada ISSN 1431-9756 ISSN 2197-6562 (electronic) ISBN 978-3-319-03169-9 ISBN 978-3-319-03170-5 (eBook) DOI 10.1007/978-3-319-03170-5 Springer Cham Heidelberg New York Dordrecht London Library of Congress Control Number: 2014938104 © Springer International Publishing Switzerland 2003, 2014 This work is subject to copyright. 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Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Cover illustration: Cover photo of the Rosette Nebulae by Stuart Heggie used with permission. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) In memory of Clare Patershuk May her scattered photons grace the Universe forever Acknowledgments This book would not have been possible without the help of many individuals. Thanks are due to Alister Ling and Doug Hube who read and suggested changes to drafts of the first edition of this book. Thanks are also due to Chris, Paul, and Jenise Finlay for their help in removing as many typographical errors as possible from the first edition. Thanks also to the many fellow amateur astronomers over the years, too numerous to list here, from whom I have learned so much. Finally, I thank my parents for instilling a boundless curiosity in me, and my wife and children for the kind patience and support they showed while I wrote this book. vii Contents 1 Introduction ............................................................................................... 1 2 The Messier Objects.................................................................................. 7 3 NGC (New General Catalogue) Objects ................................................. 143 4 IC (Index Catalogue) Objects and the Large Magellanic Cloud .......... 431 Erratum ........................................................................................................... E1 Index ................................................................................................................. 435 ix About the Author Dr. Warren H. Finlay is a Canadian citizen. He is an avid amateur astronomer and author of “The Concise Catalog of Deep-Sky Objects: Astrophysical Information for 500 Galaxies, Clusters and Nebulae,” published by Springer in 2003. He has been a Contributing Editor of the bimonthly Journal of the Royal Astronomical Society of Canada and is the recipient of the Royal Astronomical Society of Canada’s (RASC) Simon Newcomb Award for literary achievement, among several other RASC awards for dark sky preservation and astronomy education. He has traveled extensively in search of dark sky sites, and has logged thousands of deep sky objects with his telescope from all over the world. In his day job as a Professor of Mechanical Engineering at the University of Alberta, Warren has written two books, six chapters in other books, more than 140 archival journal papers, and 220 refereed conference publications – in addition to several hundred non-refereed conference publications. He is also an accomplished night sky pho- tographer, with many of his photographs gracing astronomy magazines as well as art venues. xi Chapter 1 Introduction This book is intended to give a concise summary of some of the more interesting astrophysical facts that are known about objects commonly observed by amateur astronomers. Pondering this information while viewing an object in the field has added a new level to the author’s enjoyment of deep-sky observing, and it is hoped this information will be similarly enjoyed by other amateur astronomers. The book is not intended to be read cover to cover, but rather is designed so that each object entry can be read individually one at a time and in no particular order, perhaps while at the eyepiece. A total of 550 deep-sky objects are listed as separate entries in this book, in order of their NGC (New General Catalogue) number in the main section of the book, including all the Messier objects, the Herschel 400 objects, the Royal Astronomical Society of Canada’s Finest 110 NGC objects plus 30 of the Royal Astronomical Society of Canada’s Southern Hemisphere Splendours objects. Because NGC and IC numbers were originally assigned in approximate order of an object’s location from west to east, objects that are well placed for viewing in the sky at a particular time of year occur within a few pages of each other. For convenience, the Messier objects are repeated in a separate chapter in order of their Messier number. The separate chapter on the Messier objects includes astro- photos of them, taken by Canadian amateur astronomers. The only five objects from the IC (Index Catalogue) are listed in the last chapter of the book along with the Large Magellanic Cloud which does not have its own defining NGC or IC number. W.H. Finlay, Concise Catalog of Deep-Sky Objects: Astrophysical Information 1 for 550 Galaxies, Clusters and Nebulae, The Patrick Moore Practical Astronomy Series, DOI 10.1007/978-3-319-03170-5_1, © Springer International Publishing Switzerland 2014 2 1 Introduction The following notes apply to the presentation of information for each object. Object type: This is one of the following: Open cluster – a close-knit collection of stars within the disk of our Galaxy that all formed from the same interstellar cloud in the past few billion years, usually containing fewer (usually many fewer) than a few thousand stars and often containing only a few tens of stars that are visible in an amateur telescope. Globular cluster – a close-knit collection of stars, usually outside the disk of our Galaxy, that formed many billions of years ago and contains many tens of thousands (or even more than a million) stars. Planetary nebula – this is a short-lived stage in the life of stars having masses not too different from the Sun. Near the end of the nuclear fusion stage of such a star, gas is expelled in winds from the dying star, with these winds sometimes expelling more gas in certain directions, and also interacting (e.g. with previ- ously expelled gas, binary companions, planets or magnetic fields), making interesting patterns in the gas that we see as different shapes to planetary nebulae. The gas is ionized by ultraviolet radiation from the central star, making the gas visible when electrons recombine with ions. Emission nebula – this is a region where an interstellar gas cloud has been ionized by young, hot stars near or in these clouds. The clouds are mostly made of ionized hydrogen, but small amounts of other ionized atoms, such as oxygen, also emit light (for example, doubly ionized oxygen, or OIII, emits light at a particular wavelength that is easier to see with a special OIII filter that only lets this wavelength through). Reflection nebula – this is a region where light from stars is scattered off dust in an interstellar cloud. Elliptical galaxy – as the name suggests, these are galaxies with the shape of an ellipsoid (although many are not far from being spherical in shape). Lenticular galaxy – lenticular means “lens-shaped” and this is the shape of these galaxies i.e. they are shaped like a convex lens and have a disk in their central plane (but this disk lacks spiral arms). Some have a bar in the disk, and this is noted by the classification “barred lenticular galaxy.” Spiral galaxy – these are galaxies with a disk shape that contains spiral arms within it. Those with a bar in the disk are indicated as “barred spiral galaxy.” A galaxy is said to be “early-type” if it is an elliptical or lenticular galaxy, or is a spiral galaxy with relatively tightly wound spiral arms and a large central bulge (making it an “early-type” spiral). “Late-type” spirals have less tightly wound arms and a very small bulge compared to an extended disk. Irregular galaxy – these are galaxies with no obvious rotational symmetry. Supernova remnant – the visible remains of a supernova. Asterism – a pattern of physically unrelated stars on the sky. R.A ., Dec .: The right ascension (R.A.) and declination (Dec.) coordinates of the object (Equinox 2000). R.A. and Dec. are analogous to longitude and latitude but refer to the object’s position in the sky.

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