Obituary
Written by Richard B. Larson and Linda L. Stryker
Reprinted from the Quarterly Journal of the Royal Astronomical Society, Vol. 23, 1982, pp. 162-165.
Beatrice M. Tinsley, one of the most widely known and respected theorists in modern astronomy, died on 1981 March 23 at the age of 40, following a three-year battle with cancer. Her most untimely passing shocked and saddened all who had known her and had been impressed by the extraordinary energy and verve with which she had pioneered many lines of study in cosmology and the evolution of galaxies. Beatrice Tinsley was born on 1941 January 27 in Chester, England, the second of three daughters of Edward O. E. Hill and Jean Morton Hill. Her family moved in 1946 to New Zealand and eventually settled in the town of New Plymouth, where her father was an Anglican minister, and later mayor.
She received her high-school education in New Plymouth and later attended the University of Canterbury in Christchurch, obtaining her BSc and MSc degrees in physics in 1961 and 1963. From an early age she had shown a special talent in mathematics and an abundance of industry and ambition, and as her interest in mathematics and science developed, so also did her determination to pursue her studies to the highest possible level and to excel and achieve distinction in them. Her exceptional ability and her enthusiastic pursuit of learning led, almost inevitably, to a brilliant scholastic record, and later to an equally outstanding scientific career. In 1963, having recently married physicist Brian A. Tinsley, Beatrice moved to Dallas, Texas. Finding little opportunity there to pursue her scientific interests, she enrolled in 1964 as one of the first graduate students in the recently established Astronomy Department of the University of Texas in Austin.
Despite commuting each week from Dallas and spending only half of the week in Austin, Beatrice mastered the graduate programme with awe-inspiring speed, and in 1967 completed a thesis which was a major scientific achievement, a pioneering study of the evolution of galaxies. Her first interest in astronomy had been in cosmology, but she had quickly realized that further progress in this subject depended on understanding how galaxies evolve, so she devised the technique of synthesizing models of galaxies by putting together the available empirical and theoretical information on the evolution of stars to deduce how galaxies evolve in colour and luminosity. This thesis marked the beginning of modern detailed studies of galactic evolution, and with-it Beatrice Tinsley’s career in the field was firmly launched. Her thesis contained two major conclusions: (1) the colours of galaxies of all Hubble types can be explained as a result of different histories of star formation without assuming different ages, and (2) galaxies fade rapidly enough that substantial corrections are required when they are used as ‘standard candles’ in cosmological studies. These conclusions were not immediately appreciated by all, and Beatrice felt at first that it was difficult for her to get her work accepted, but over the next several years her results became well established through further work on her part and confirmation or rediscovery by other investigators.
Family responsibilities brought a brief pause in her career after she adopted a son Alan in 1966 and a daughter Teresa in 1968, but her growing professional ambitions could not be set aside, and within a few years she had resumed her research career with the full force of her prodigious energy, beginning a prolific series of projects and publications that continued until her death. She rapidly established acquaintance with many prominent astronomers and initiated numerous collaborative efforts combining the expertise of individuals working in diverse areas. All who worked with her were impressed with her broad knowledge and her ability to quickly grasp and synthesize information from many fields.
There is not space to even list all the projects on which she worked, but they expanded in many directions the study of galactic evolution and its relations to cosmology. To mention a few examples, several papers studied stellar populations in the solar neighbourhood and in star clusters, in order to obtain improved information about late stages of stellar evolution and the evolutionary history of our Galaxy. An important series of papers on the chemical evolution of galaxies combined concepts of galactic evolution with information on stellar chemical compositions and nucleosynthesis and provided a careful study of the possible processes and models; these papers emphasized that the simplest models often fail and that realistic models must be more complex, involving features like gas flows and inhomogeneities. Several papers also addressed the evidence concerning the origins of different types of supernovae, and their relation to stellar evolution and nucleosynthesis. In addition to the effect of luminosity dimming on the use of galaxies as standard candles in cosmology, Beatrice studied the use of the diameters and surface brightnesses of galaxies and the use of galaxy counts and the integrated background light as possible cosmological tests. In all cases similar conclusions were reached, namely that the observations are at least as sensitive to the evolution of galaxies as to the differences between the cosmological models being tested. As a result of this work, it eventually became clear that most ‘cosmological’ observations actually provide more information about galaxies than about cosmology, and that the evolution of galaxies is actually a very rich subject of study in itself. For example, such ‘cosmological’ observations as counts of faint galaxies and measurements of the extragalactic background light are sensitive to whether galaxies experience an initial bright flash of star formation or whether star formation occurs more gradually; they are also sensitive to the mix of galaxy types and whether this changes with time. Tentative evidence for an early phase of rapid star formation in at least some galaxies has appeared in some of the data, but the identification of a bona fide ‘primeval galaxy’ undergoing an initial intense burst of star formation, a subject to which Beatrice also gave attention in several papers, has as yet proved elusive. A possible reason for this, discussed in yet another of her papers, is that star formation in young elliptical galaxies occurs not in a single large burst, but less spectacularly in a series of small ones.
Despite her burgeoning career and reputation, Beatrice was never able to obtain academic employment in Dallas, a fact which made her increasingly frustrated, even though she enjoyed a series of visiting appointments at the California Institute of Technology, the University of Maryland, the University of Texas at Austin, and the Lick Observatory.
Finally, she decided to leave Dallas and seek her fortunes elsewhere, and in 1975 she was appointed Associate Professor of Astronomy at Yale University, an appointment which pleased her greatly and marked the beginning of a very fruitful association with that institution. She interacted with and helped unify the existing activities at Yale in stellar evolution, star formation, and extragalactic astronomy, and contributed much to Yale’s eminence in the areas of stellar and galactic evolution. In 1978 she was promoted to Professor of Astronomy, an achievement which finally amply fulfilled her once frustrated ambitions to find suitable academic employment. It was a tragic irony of fate that she learned of her promotion to Professor at the same time that she learned that she had melanoma, a particularly intractable form of cancer that was to lead to her death three years later. Fortunately, her health held out remarkably well for most of that period, and she remained scientifically productive until very near her death in 1981.
Beatrice showed her talents in other ways than her prolific output of scientific papers, of which close to one hundred were published.
In 1977 she organized an outstandingly successful conference at Yale on The Evolution of Galaxies and Stellar Populations’, at which many new trends in extragalactic research were exhibited. Her broad acquaintance with the field and her high standards were manifested in the content of the meeting and the published proceedings which she edited, and which became an important reference in the field. She herself attended a great many meetings as an invited speaker and was well known for her lucid and even inspiring review talks. She served with distinction on University and national committees and became known even in non-scientific circles for her vigour, astuteness, and uncompromising standards.
In the Yale Astronomy Department, she served as Director of Graduate Studies, and devoted a generous share of her time and energy to the concerns of the graduate students. Mindful of the help she had received from more senior astronomers earlier in her career, she gave much help and encouragement to students and younger colleagues. She initiated a series of weekly student-faculty lunches, hosted gatherings with visitors, and took students to meetings and introduced them to other astronomers and promoted their work. Young astronomers anywhere in the world might receive a letter from Beatrice commending them for a piece of good work and urging them to continue their efforts; she did not regard them as rivals but rather as co-investigators in the greater enterprise of understanding the Universe.
Perhaps one of her greatest contributions to science does not even appear in print, being alluded to only in the many acknowledgments at the end of papers where her name is mentioned. A great many people were stimulated and inspired by her vitality, her joy in the pursuit of knowledge, and the enthusiasm that she transmitted to others. All avenues of study were to be pursued with vigour, and many projects were launched or strongly influenced as a result of her initiatives. She provided the focus and, directly or indirectly, the driving force behind most of the work on galactic evolution that was done during her lifetime. Moreover, all those who worked in the field knew that their work would receive her close and critical attention, and her comments were often sought and sometimes feared, because she did not tolerate what she considered to be incorrect or inadequate arguments.
Although her career was not long in years, it was long enough for her to have a greater impact on astronomy than most astronomers could hope to have over a much longer career. As remarkable as the rest of her life was the way that Beatrice coped with her final catastrophic illness. As a person of strong ambition, she was initially devastated at the discovery of cancer, but quickly became determined to make the best possible use of whatever time remained. She underwent a series of operations, but her still abundant energy and drive helped her to recover quickly from them, and she soon reappeared in her office ready to carry on with all her normal activities.
During this period she produced some of her most significant scientific contributions, including an extensive and widely quoted review on the evolution of the stars and gas in galaxies, the culmination of a long effort to model the stellar content of elliptical galaxies on the basis of detailed spectra, a study of the evolution of disc galaxies and the origin of SO galaxies, a demonstration of evidence for different proportions of dark mass in galaxies of different Hubble type, and a number of other important works. In 1980 September her health finally failed when it was found that her cancer had spread to vital organs, and in November a brain tumour left her partially paralyzed and confined thereafter to the university infirmary. Although it had been expected that the subsequent course of her illness would be quick, she instead showed a remarkable improvement and surprised her doctors by how well and how long she held up. She was able to resume some of her scientific activities, such as reading, correspondence, and consulting with students and colleagues. Even the loss of use of her right hand could not stop her, and her final paper, a detailed mathematical treatment of chemical evolution conceived and completed while she was confined to the infirmary, was laboriously written out with her left hand. She died shortly after this paper was submitted for publication. During her months in the infirmary, it became abundantly clear that she had gained vast numbers of friends and admirers throughout the scientific world, and mail, flowers, and visitors flowed into her room in a steady stream. All who visited her or spoke with her by telephone, even the doctors and nurses, were amazed at her cheerfulness and determination in a situation where she was expected to live only a matter of weeks. Inevitably she suffered moments of depression when her condition took a turn for the worse, but she always bounced right back. She greatly appreciated the attention and support she received from her many friends, insisting that it was the only thing that made it possible for her to appear courageous and cheerful. For her the pain of having to depart from the world at the height of her career was eased just a little by the realization that she was doing so in the full glow of attention and recognition, rather than as a forgotten relic of a past era.
OBITUARY IN THE NEW YORK TIMES - Overlooked No More: Beatrice Tinsley, Astronomer Who Saw the Course of the Universe, written by Dennis Overbye, July 18, 2018.