Sunday, May 22, 2011, 1:30 PM - 3:00 PM Special Session Staffordshire
The Legacy of Annie Jump Cannon: Discoveries and Catalogs of Variable Stars.
Barbara L. Welther1
1Smithsonian.
1:35 PM - 1:55 PM
Staffordshire
This paper will review the many variable-star projects and publications that Cannon brought to fruition in her 45-year career at Harvard College Observatory.
In 1896, when Cannon joined the "Corps of Women Computers" at HCO, Williamina Fleming already enjoyed world-wide acclaim for her discoveries of novae on photographs of stellar spectra.
Antonia Maury had also become renowned: she had discovered and analyzed a rare spectroscopic binary star, Beta Aurigae. At that time, such discoveries made headlines in newspapers, especially because they were made by women who studied astronomy by day!
When Cannon was not actively involved in classifying stellar spectra, she took up HCO's project of cataloging observations of variables. As a result, she discovered thousands of long-period variable stars and half a dozen novae in the Milky Way. In 1903 she published "A Provisional Catalogue of Variable Stars" in Harvard Annals 48. Subsequently, Margaret Walton Mayall and Florence Campbell Bibber continued cataloging the variables through 1941, when Cannon died.
In 1918, when Cannon and others such as Edward Pickering and Solon Bailey, were made honorary members of the American Association of Variable Star Observers, Cannon wrote: "I assure you it is a pleasure to be associated in this way, with a company of ardent observers and investigators, whose results are of so much value and carried on with such enthusiasm. It well be a spur to me in my future work, especially as to the new Catalogue of Variable Stars, which I hope to finish before very long."
Anne S. Young: Professor and Variable Star Observer Extraordinaire
Katherine Bracher1
1Whitman College.
1:55 PM - 2:10 PM
Staffordshire
Anne Sewell Young (1871-1961) was one of the eight original members of the AAVSO, to which she contributed more than 6500 observations over 33 years. She also taught astronomy for 37 years at Mount Holyoke College; among her students was Helen Sawyer Hogg. This paper will look at her life and career both at Mount Holyoke and with the AAVSO.
The Stars Belong to Everyone: Astronomer and Science Writer Dr. Helen Sawyer Hogg (1905-1993)
Maria J. Cahill1
1Edison State College.
2:10 PM - 2:40 PM
Staffordshire
University of Toronto astronomer and science writer Helen Sawyer Hogg (President of
the AAVSO 1939-41) served her field through research, teaching, and administrative leadership.
Additionally, she reached out to students and the public through her Toronto Star newspaper
column entitled “With the Stars” for thirty years; she wrote The Stars Belong to Everyone, a
book that speaks to a lay audience; she hosted a successful television series entitled Ideas; and
she delivered numerous speeches at scientific conferences, professional women’s associations,
school programs, libraries, and other venues. This paper will illumine her life and the
personal and professional forces that influenced her work.
Variable Stars and Constant Commitments: The Stellar Career of Dorrit Hoffleit
Kristine Larsen1
1Central Connecticut State University.
2:40 PM - 3:00 PM
Staffordshire
Astronomer, educator, and science historian Dorrit Hoffleit (1907-2007) was widely respected by the amateur and professional astronomical community as a mentor and an ardent supporter of independent research. Her more than 600 catalogues, books, articles, book reviews, and news columns cover myriad aspects of astronomy, from variable stars and stellar properties to meteor showers, quasars, and rocketry. She also made important contributions to the history of astronomy. Hoffleit worked at the Harvard College Observatory from 1927-1956, where she discovered over 1200 variable stars. When Director Harlow Shapley retired from Harvard, Hoffleit gave up her tenured position and moved to Yale University, where she was placed in charge of the Yale Catalog of Bright Stars. At the same time, she was offered a position as director of the Maria Mitchell Observatory on Nantucket Island in Massachusetts. Hoffleit split her dual positions into six-month stints and remained director at the Mitchell Observatory for 21 years, developing a summer research program that engaged more than 100 undergraduate students (all but three of them women) in variable star research. Up until shortly before her death, she continued to work tirelessly on selected projects, and she was in high demand as a collaborator with colleagues at Yale and elsewhere. She was especially devoted to the American Association of Variable Star Observers (AAVSO) in part because it brought together amateur and professional astronomers in collaboration. She served on the organization’s council for 23 years and as its president from 1961-1963. In 2002, the AAVS0 published her autobiography, Misfortunes as Blessings in Disguise, in which Hoffleit explains how she always felt blessed by the opportunities in her life, even those which initially seemed misfortunes, and above all else valued creativity, flexibility, collegiality, and intellectual freedom in her professional life.
Sunday, May 22, 2011, 3:20 PM - 5:30 PM HAD II: Variable Star Astronomy in Theory and Practice Special Session Staffordshire
King Charles` Star: A Multidisciplinary Approach to Dating the Supernova Known as Cassiopeia A
Martin Lunn1
1Yorkshire Museum, United Kingdom.
3:25 PM - 3:40 PM
Staffordshire
Few astronomical phenomena have been as studied as the supernova known as Cassiopeia A. Widely believed to have occurred in the latter half of the seventeenth century, it is also thought to have gone unrecorded. This paper will argue that Cas A did not go unobserved, but in fact was seen in Britain on May 29, 1630, and coincided with the birth of the future King Charles II of Great Britain. This ‘noon-day star’ is an important feature of Stuart/Restoration propaganda, the significance of which has been widely acknowledged by historians and literary experts. The argument here, however, is that in addition the historical accounts provide credible evidence for a genuine astronomical event, the nature of which must be explained. Combining documentary analysis with an overview of the current scientific thinking on dating supernova, the authors put forward their case for why Charles’ star should be recognized as a sighting of Cas A. Finally, it will be argued that a collaborative approach between the humanities and the sciences can be a valuable tool, not just in furthering our understanding of Cas A, but in the dating of supernovae in general.
John Goodricke, Edward Pigott, and Their Study of Variable Stars
Linda M. French1
1Illinois Wesleyan Univ..
3:40 PM - 4:00 PM
Staffordshire
John Goodricke (1764-1786) and Edward Pigott (1753-1825) are credited with determining the first accurate periods for several important variable stars. Goodricke's name is associated with the determination of the period of the eclipsing binary Algol (Beta Persei); for this he was awarded the Copley Prize of the Royal Society of London. He also determined the periods of the contact binary Beta Lyrae and of Delta Cephei, the prototype Cepheid variable. Around the same time, Edward Pigott obtained the period of Eta Aquilae, another Cepheid. In actuality, the two collaborated on all these observations; today we would call them co-discoverers. Goodricke is the better known of the two, in part because he won the Copley Medal, in part because of his tragically short life, and in part because he was deaf. Edward Pigott was the more experienced observer, having worked with his father Nathaniel on determining the longitudes of several cities on the Continent. Evidence shows, however, that Goodricke had some astronomical experience while a student at the Warrington Academy. The journals of the two show that they developed a partnership that made the most of both their talents over the brief time (less than five years) they worked together before Goodricke's death. Today, the two are remembered as having suggested eclipses as the cause for the periodic dimming of Algol. This explanation is accepted today as the correct one. In their day, however, most eminent astronomers believed that starspots were a more likely cause for the dimming. By the time of John Goodricke's death, he seems to have accepted that explanation as well. A study of the work of Goodricke and Pigott contains many lessons for today's observers of variable stars.
This work was supported by an AAS Small Research Grant and by the Pollack Award of the Dudley Observatory.
The development of early pulsation theory, or, how Cepheids are like steam engines"
Matthew Stanley1
1New York University.
4:00 PM - 4:25 PM
Staffordshire
The pulsation theory of Cepheid variable stars was a major breakthrough of early twentieth-century astrophysics. At the beginning of that century, the basic physics of normal stars was very poorly understood, and variable stars were even more mysterious. Breaking with accepted explanations in terms of eclipsing binaries, Harlow Shapley and A.S. Eddington pioneered novel theories that considered Cepheids as pulsating spheres of gas. These theoretical models relied on highly speculative physics, but nonetheless returned very impressive results despite attacks from figures such as James Jeans. Surprisingly, the pulsation theory not only depended on developments in stellar physics, but also drove many of those developments. In particular, models of stars in radiative balance and theories of stellar energy were heavily inspired and shaped by ideas about variable stars. Further, the success of the pulsation theory helped justify the new approaches to astrophysics being developed before World War II.
Frank Elmore Ross and his Variable Star Discoveries
Wayne Osborn1
1Yerkes Observatory/Central Mich. U.
4:30 PM - 4:45 PM
Staffordshire
Frank Elmore Ross (1874-1960) was a talented astronomer that excelled in such diverse fields as computational astronomy, optical instrument design and astrophotography. Today he is remembered in astronomy mainly for his lists of stars of high proper motion, many of which are among our closest neighbors. A by-product of his searches for high proper motion stars was the discovery of 379 new variable stars. The identities of a number of these “Ross variables” are still uncertain and the variability yet to be confirmed more than eighty years after publication, largely due to imprecise or erroneous coordinates. Ross’s original observing cards and plates have been located and are being used to re-examine the stars. The cases of uncertain identity or variability are being resolved, and better magnitudes are being determined for these early-epoch observations. Many of the Ross variables are poorly studied and follow-up observations of a few of these stars have yielded some interesting results.
Stellar Pulsation Theory from Arthur Stanley Eddington to Today
Steven D. Kawaler1, C. J. Hansen2
1Iowa State Univ., 2University of Colorado.
4:45 PM - 5:05 PM
Staffordshire
While one could question that Eddington was the pioneer in theoretical work directly addressing the pulsating variable stars, there is no doubt that his work in the first part of the 20th Century set the stage for a transformation of theoretical astrophysics. After Eddington (the 1940s to the present day) stellar pulsation theory evolved from analytic theory into the realm of computational physics. Starting from Eddington's formulation, the flexibility provided by numerical solutions enabled exploration of systematics of pulsating variable stars in vastly greater detail. In this talk, we will trace this development that led to theoretical explanations of period-luminosity relations, new mechanisms of pulsation driving, connections with mass loss and stellar hydrodyamics, and to modern asteroseismic probes of the Sun and the stars.
The AAVSO Photoelectric Photometry Program in its Scientific and Socio-Historic Context
John R. Percy1
1Univ. of Toronto, Canada.
5:05 PM - 5:30 PM
Staffordshire
Photoelectric photometry began in the 1900s through the work of Guthnick, Stebbins, and others who constructed and used photometers based on the recently-discovered photoelectric effect. The mid 20th century saw a confluence of several areas of amateur interest: astronomy, telescope making, radio and electronics, and general interest in space. This is the time when AAVSO photoelectric photometry (PEP) began, with observers using mostly hand-built photometers on hand-built telescopes. The 1980s brought a revolution: affordable off-the-shelf solid-state photometers, and infrastructure such as the International Amateur-Professional Photoelectric Photometry (IAPPP) conferences, books, and journal. The AAVSO developed a formal PEP program in the early 1980s. Its emphasis was on long-term monitoring of pulsating red giants. It was competing, not always successfully, with programs such as active sun-like binaries (RS CVn stars) which offered "instant gratification" in the form of publicity and quick publications. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback to observers, produced extensive scientific results. In this presentation, I shall describe, as examples, my own work, its scientific significance, its educational benefit to dozens of my students, and its satisfaction to the observers. To some extent, the AAVSO PEP program has been superceded by its CCD program, but there is still a useful place for ongoing PEP observations of thousands of variable stars. Reference: http://www.aavso.org/sites/default/files/newsletter/PEP/lastpepnl.pdf Acknowledgements: I thank NSERC Canada for research support, my students, and AAVSO staff and observers, especially Howard Landis.
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