Astronomers Obser v ing Guides Series Editor Dr. Michael D. Inglis, BSc, MSc, Ph.D. Fellow of the Royal Astronomical Society Suffolk County Community College New York, USA inglism@sunysuffolk.edu For further volumes: http://www.springer.com/series/5338
Martin Griffiths Planetary Nebulae and How to Observe Them
Martin Griffiths University of Glamorgan Glyntaf, United Kingdom ISSN 1611-7360 ISBN 978-1-4614-1781-1 e-isbn 978-1-4614-1782-8 DOI 10.1007/978-1-4614-1782-8 Springer New York Dordrecht Heidelberg London Library of Congress Control Number: 2011946227 Springer Science+Business Media, LLC 2012 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com)
For Dena
Preface Planetary nebulae are among the diverse forms of astronomical objects available for amateur study and may be some of the most inspiring sights nature has to offer. Seldom is there a group with such a range of shapes, sizes and colors that have particular idiosyncrasies from object to object. Planetary nebulae are fascinating, beautiful and enchanting; what could be more wonderful than contemplating these small celestial objects, realizing that 1 day our Sun may join this band of heavenly entities? Their ethereal nature, short lifetime and range of forms make observing them a most pleasing study. I have been entranced by them from a young age and can still remember my first look at the famous Dumbbell Nebula, Messier 27, through a small refractor I had purchased from a friend. It was a puff of gas, blue-gray in color with a definite indentation on both sides nestled in a field of fainter stars, yet overflowing and seeming to envelop a few. I was hooked; since then, all planetaries have filled me with a delight that is not fully shared with other objects. Yes, I enjoy looking at faint galaxies, bright nebulae and majestic star clusters, but planetary nebulae are still my favorite objects and the ones I preferentially seek out while observing, no matter what telescope I am using. I am fortunate in that my life in both amateur and professional astronomy overlaps our increasing understanding of these lovely phenomena an understanding that complements my frequent views of faint smudgy forms almost lost in the darkness of the midnight sky. I hope that this volume will provide the tools necessary to start searching for these wonderful entities. It does not matter what the aperture of your telescope is or how frequently you observe, there are enough bright objects included in this book to please and delight most observers, and hopefully the illustrations will satisfy an armchair astronomer. I have attempted to strike a balance between easily visible objects that can be seen in any telescope or binoculars, to nebulae that are a direct challenge to those with large aperture equipment. With over 1,000 objects to choose from, the enclosed observing list represents just 10% of the number that could theoretically be seen or imaged, although it is fair to report that this 10% probably represents the best of the catalogues for amateur study. I have also included an historical and physical analysis of planetary nebulae in order that the reader has a ready volume covering both observational and astrophysical aspects of the subject, which will give added understanding and impetus to the search. I find that when teaching students, the ability to see a faint or fuzzy blob of light is augmented by the fuller physical understanding of its intrinsic nature, leading to a greater appreciation for the object. How often have we shown someone a celestial delight we consider significant, only to have that observer disparage the eyepiece view? Observing any deep sky object with relatively small telescopes is not going to reveal a professional, observatory quality image, but this lack can be turned to our advantage by imparting some fore knowledge on the Preface vii
Preface inherent nature of the item viewed, enabling an appreciation of cosmic distance, scale and power from our fleeting Earthly platform. I have also included within the finder maps of some objects several additional planetary nebulae as they were shown in Sky Map Lite. These P-K nebulae may become challenge objects for observers wishing to go beyond the range of this book, and any information on them may be gleaned from the P-K catalogue included here or from sky chart programs or the Internet. In the final analysis, I want observers to enjoy their experiences in hunting down these wonderful nebulae and discovering them for themselves. Our universe is not something that can be fully appreciated by superlatives, by numbers or formulae or by concentrating on specifics; it is something to be sensed, experienced, savored and valued. I especially feel this way when observing planetary nebulae. The great American poet Walt Whitman, conscious of such emotions penned: When I heard the learned astronomer, When the proofs, the figures, were ranged in columns before me, When I was shown the charts and diagrams, to add, divide, and measure them, When I sitting heard the astronomer where he lectured with much applause in the lecture-room, How soon unaccountable I became tired and sick, Till rising and gliding out I wandered off by myself, In the mystical moist night-air, and from time to time, Looked up in perfect silence at the stars. (Leaves of Grass 1882) I hope this small book will help one to grow in knowledge and appreciation of one striking facet of the universe around us. Martin Griffiths BSc MSc FRAS University of Glamorgan UK viii
Acknowledgements This work has been the culmination of many years of research and practical activity in both amateur and professional astronomy. As such, it would be impossible to name all the people whom I have encountered who have provided encouragement and support for this venture. However, I would like to thank the Faulkes telescope team for their encouragement and access to the Faulkes telescopes to provide the images, especially Dr. Sarah Roberts for supplying the illustrations of the EM Spectrum, the H-R diagram and the frontispiece photograph of Abell 39; the editorial staff at Springer for their helpful comments and suggestions and Ted Forte of the Astronomical League for his communication and encouragement. Unless otherwise acknowledged in the text, all photographs have been taken by the author and are copyrighted. Acknow ledgements ix
About the Author Martin Griffiths is an enthusiastic science communicator, writer and professional astronomer. Over his career he has utilized history, astronomy and science fiction as tools to encourage greater public understanding of science. He is a recipient of the Astrobiology Society of Britain s Public Outreach Award (2008) and the Astronomical League s Outreach Master Award (2010). He also holds the League s Master Observer certificate and has written or contributed to over 100 published science articles for many journals. He was one of the founder members of NASA s Astrobiology Institute Science Communication Group, which was active between 2003 and 2006; he also managed a multi-million-pound ESF programme in Astrobiology for adult learners across Wales between 2003 and 2008. Since then he has been involved in promoting adult education, assisting in the development of a new observational astronomy award at the University of Glamorgan and various other projects, including initial consultation on the setup of an observatory in Andalucia, Spain. He is a consultant to the Welsh government through his involvement with the Dark Sky Discovery initiative, enabling public access to dark sky sites in association with Dark Sky Wales, Dark Sky Scotland and Natural England. Martin is a Fellow of the Royal Astronomical Society and a member of the Astrobiology Society of Britain, the European Society for the History of Science, the British Astronomical Association, the British Science Association, the Webb Deep-Sky Society, the Society for Popular Astronomy, and the Astronomical League. He is also a local representative for the BAA Campaign for Dark Skies and is a member of the Honourable Society of Cymmrodorion, dedicated to promoting the literature, science and arts of Wales. About the Author xi
Contents Preface............................................................. Acknowledgements.................................................. About the Author................................................... vii ix xi Chapter 1 A Short History of Planetary Nebulae........................ 1 Further Discoveries........................................ 1 The Nature of the Nebulae and Modern Catalogues............ 3 Chapter 2 The Evolution of Planetary Nebulae......................... 7 The Lives of the Stars...................................... 7 Stages in the Life Cycle of a Sun-like Star..................... 9 The Asymptotic Giant Branch............................... 10 Proto-Planetary Nebulae and Dust........................... 12 Interactive Winds.......................................... 13 Emissions from Planetary Nebulae........................... 14 Central Stars.............................................. 16 Planetary Envelopes....................................... 17 Binary Stars and Magnetic Fields............................ 19 Lifetimes of Planetary Nebulae.............................. 21 Conclusion............................................... 21 Chapter 3 Observing Planetary Nebulae............................... 23 Telescopes and Mountings.................................. 23 Telescope Mounts.......................................... 26 Eyepieces................................................. 27 Limiting Magnitudes and Angular Resolution................. 29 Transparency and Seeing................................... 31 Dark Adaptation and Averted Vision......................... 32 Morphology of Planetary Nebulae........................... 33 Nebular Filters............................................ 35 Star Charts, Observing and Computer Programs............... 38 Observing Procedures...................................... 42 Chapter 4 Photographing Planetary Nebulae........................... 45 Camera Equipment........................................ 45 Software.................................................. 48 Filters for Astrophotography................................ 49 Shooting................................................. 50 Conclusion............................................... 53 Contents xiii
Chapter 5 Planetary Nebulae Catalogues.............................. 55 Main Planetary Nebulae.................................... 56 Additional Planetary Nebulae............................... 58 Contents Chapter 6 Planetary Nebulae by Constellation.......................... 81 Andromeda............................................... 83 Apus..................................................... 85 Aquarius................................................. 87 Aquila................................................... 90 Ara...................................................... 103 Auriga................................................... 106 Camelopardalis........................................... 108 Canis Major.............................................. 111 Carina................................................... 113 Cassiopeia................................................ 119 Centaurus................................................ 123 Cepheus.................................................. 126 Cetus.................................................... 129 Chameleon............................................... 131 Corona Australis.......................................... 133 Corvus................................................... 135 Cygnus................................................... 137 Delphinus................................................ 154 Draco.................................................... 157 Eridanus................................................. 160 Fornax................................................... 162 Gemini................................................... 164 Hercules................................................. 170 Hydra.................................................... 174 Lacerta................................................... 178 Leo...................................................... 180 Lepus.................................................... 182 Lupus.................................................... 184 Lynx..................................................... 190 Lyra..................................................... 192 Monoceros............................................... 195 Musca.................................................... 198 Norma................................................... 203 Ophiuchus................................................ 205 Orion.................................................... 211 Pegasus.................................................. 214 Perseus................................................... 219 Puppis................................................... 225 Pyxis..................................................... 229 Sagitta................................................... 232 xiv
Sagittarius................................................ 236 Scorpius.................................................. 253 Scutum.................................................. 258 Taurus................................................... 260 Triangulum Australe....................................... 262 Ursa Major............................................... 266 Vela...................................................... 268 Virgo.................................................... 272 Vulpecula................................................ 274 Chapter 7 A Planetary Nebulae Marathon.............................. 277 Why Introduce Another List?................................ 277 Overlaps with Other Object Lists............................ 278 Outstanding Planetaries.................................... 279 References and For Further Reading................................... 281 Index.............................................................. 285 Contents xv