Galaxies and their Masks David L. Block · Kenneth C. Freeman · Ivânio Puerari Editors Galaxies and their Masks A Conference in Honour of K.C. Freeman, FRS 123 Editors David L. Block Kenneth C. Freeman School of Computational Australian National University and Applied Mathematics Weston Creek, ACT 2611, Australia University of the Witwatersrand [email protected] Johannesburg WITS 2050, South Africa [email protected]; [email protected] Ivânio Puerari Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE) Santa Maria Tonantzintla, Puebla 72840, México [email protected] ISBN 978-1-4419-7316-0 e-ISBN 978-1-4419-7317-7 DOI 10.1007/978-1-4419-7317-7 Springer New York Dordrecht Heidelberg London Library of Congress Control Number: 2010936375 c Springer Science+Business Media, LLC 2010 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) Preface The year: 1660. The date: November 28. Present: The Lord Brouncker, Mr Boyle, Mr Bruce, Sir Robert Moray, Sir Paule Neile, Dr Wilkins, Dr Goddard, Dr Petty, Mr Ball, Mr Hooke, Mr Wren, and Mr Hill. Occasion: A lecture by Mr Wren at Gresham College, United Kingdom. After Christopher Wren had delivered his lecture at Gresham College on that historic occasion in November 1660, “they did according to the usual manner, withdraw for mutual converse.” It was in 1660 that the Royal Society was founded, with 12 persons present. This year, 2010, is thus a special year for scientists worldwide: it celebrates the 350th anniversary of the founding of the Royal Society, whose current President is Martin Rees. One of the enormous challenges facing scientists in the 1600s was the great need for the classification of objects they were studying, particularly in the field of botany. The seeds for classification lie in the works of the British naturalist John Ray (1628–1705), who commencing in 1660 with his Catalogus plantarum circa Cantabrigiam nascentium (Catalogue of Cambridge Plants) – published in the year in which the Royal Society was founded – and ending with the posthumous publica- tion of Synopsis Methodica Avium et Piscium in 1713, pioneered systematic studies on plants, birds, mammals, fish, and insects. In these works, Ray brought order to the chaotic mass of names in use by the naturalists of his time. Like Linnaeus, Ray searched for the “natural system,” a clas- sification of organisms that would reflect the Divine Order of Creation. Unlike Lin- naeus, whose plant classification was based entirely on floral reproductive organs, Ray classified plants by overall morphology: the classification in his 1682 book Methodus Plantarum Nova draws on flowers, seeds, fruits, and roots. Ray’s plant classification system was the first to divide flowering plants into monocots and dicots. This method produced more “natural” results than “artificial” systems based on one feature alone; it expressed the similarities between species more fully. Ray’s system greatly influenced later botanists such as Jussieu and de Candolle and schemes based on total morphology came to replace those which focused on only v vi Preface one feature or organ. Ray cautioned against blind acceptance of authorities: in The Wisdom of God,hewrote: Let it not suffice to be book-learned, to read what others have written and to take upon trust more falsehood than truth, but let us ourselves examine things as we have opportunity, and converse with Nature as well as with books. And so it is with galaxies. We need to observe them; we need to classify them as comprehensively as possible. The early seeds for galaxy classification were sown by an amateur astronomer, John Reynolds, who rose to the position of President of the Royal Astronomical Society of London. Hubble had urged Reynolds to throw his ideas into a galaxy classification scheme, which Reynolds duly did. The name of John Reynolds today is almost unknown to the modern astronomical community; for a full discussion of Hubble’s failure to acknowledge his source Reynolds, the reader is referred to the book Shrouds of the Night authored by D.L.B. and K.C.F. What has emerged is that galaxies are extremely complex systems, each present- ing a different set of “masks.” The use of the word “masks” in galaxy morphology can be traced back approximately two decades, as described in a paper “Cosmic Masks Still Dance” by one of us (DLB). The important point here is that without a detailed understanding of galaxies and their masks, astronomers walk in a land of shadows. There are many masks: masks of cosmic dust, dark matter masks, dynamical masks – the list continues! These masks “dance” – in other words, they are dynam- ically active. Masks of dust have today taken central stage, whether it be in the study of super- novae (Chapter “Supernovae, Dust, and Cosmology” by Schmidt, this volume) or of galaxies. In earlier years, dust was considered as somewhat of a nuisance; something not to be a grand focal point of research. The late Mayo Greenberg often reflected on the challenges he encountered in his early laboratory days. Enter astronomer Ben Gascoigne, who was a close colleague and friend of one of ours (KCF), who passed away in March of this year. Gascoigne did so much of his pioneering observations of variable stars in the Large Magellanic Cloud by having the Director at Mt. Stromlo, Sir Richard Woolley, allocate 9 months of time to him and to his colleague, Gerry Kron. The instrument: the 30-in. Reynolds reflector, donated by the same John Reynolds we met earlier. In those formative years, this telescope ranked as one of the largest telescopes in the southern hemisphere. While the German astronomer Walter Baade had access to the giant 200-in. reflector telescope in California, Ben recalls how thrilled he was to be given unlim- ited access to the Reynolds instrument in the early 1950s. At this time, Gascoigne, Kron, and Baade were intensely interested in determining distances to nearby galax- ies. From the northern hemisphere, Baade could observe Cepheid variable stars in the Andromeda Spiral, but not in the Magellanic Clouds – which are solely the domain of observers in the southern hemisphere. Preface vii Those Magellanic Clouds held many secrets: it is no wonder that they have been referred to as Rosetta Stones. The results of 9 months of observing time with a modest telescope follow in Gascoigne’s own words: ...the dust content of the galaxy [the Milky Way] came out three times greater ...the Mag- ellanic Clouds twice as far away [as hitherto assumed], the cosmic distance scale twice as large, and the universe twice as old ...And the piece I liked, the key observations were made with a 30-inch [the Reynolds telescope], as opposed to Baade’s 200-inch. Gascoigne could clearly see the effects of masks of cosmic dust in his obser- vations of our Milky Way galaxy. Prior to the photographic era, such masks were captured visually. In this context, one is reminded of an exquisite set of drawings of the Milky Way, produced at Birr Castle in Ireland, by the German astronomer Otto Boeddicker (1853–1937). Boeddicker became the astronomical assistant to Lawrence Parsons, the 4th Earl of Rosse. Boeddicker’ drawings of the Milky Way (one of these is reproduced in Fig. 1) are breathtaking and the set, made over a period of 6 years, was published in 1892. Fig. 1 A remarkable drawing of the Milky Way by Otto Boeddicker, astronomical assistant to Lawrence Parsons, 4th Earl of Rosse It is fitting to hold a conference “Galaxies and their Masks” now, to assess the situation in 2010. (Note from David: The principal reason for selecting the year 2010 was that Ken turns 70 in 2010, and astronomers around the globe were eager to celebrate Ken’s 70th birthday). The venue chosen was in the Namib Desert: Sossusvlei, with its spectacular set of orange-reddish dunes, to be precise. Sossusvlei lies within the Namib-Naukluft National Park and is fed by the Tsauchab river. The area boasts a veritable sea of viii Preface sand dunes, some rising to more than 300 m above the desert floor. Life in the desert sands is diverse, having adapted to arid conditions. One is reminded, for example, of the “fog basking” beetle in the Namib Desert known as Onymacris unguicularis. The beetle derives its supply of water from aperiodic fog collection. To quote ecol- ogists Hamilton and Seeley, “The Namib Desert along the south-western coast of Africa supports a sand dune fauna without counterpart elsewhere in the world.” Namib is the Nama word for open space, and the Namib Desert (considered to be the oldest desert on the planet) provides the name for the land of open spaces – Namibia. Open spaces below, and open spaces above: each night, the Via Lactea or Milky Way delineated a gargantuan arch above our heads; the Large Magellanic Cloud was particularly magnificent. The conference itself took 2 years of planning.