The Lady was a Spectrographic Pioneer
Williamina Stevens was born in Dundee, Scotland on May 15th, 1857. She was one of nine children and all accounts relate a normal childhood. When Williamina was fourteen, she went to work as a pupil-teacher. (Pupil-teachers acted as a teacher of younger children, learning from observation and practical application, while simultaneously completing their own educations.) At twenty, she married James Fleming, who was an accountant and a widower. The couple had one son, Edward Fleming.
The following year, Williamina and her husband emigrated to Boston, Massachusetts. Not long after, her husband abandoned her and their unborn child. Having to fend for herself and her child, she worked as a maid in the home of Professor Edward Pickering, who was the director of the Harvard College Observatory (HCO).
Professor Pickering’s wife, Elizabeth, recognize in Williamina, or “Mina” as they called her, had an innate intelligence and many talents beyond housekeeping and the maternal arts. Upon his wife’s recommendation, in 1879, Professor Pickering hired Williamina to do some part-time administrative work at the Harvard Observatory.
By 1881, Professor Pickering also noted that Williaminia had great potential and invited er to join the HCO, teaching her how to analyze stellar spectra. She became one of the founding members of the Harvard Computers, an all woman cadre of “human computers” that Professor Pickering hired to compute the mathematical classifications and edit the observatory’s publications. A rather brave move, but the Professor recognized Williaminia’s brilliance and believing in her, forged ahead. The Harvard Computers included astronomer Henrietta Swan Leavitt, Annie Jump Cannon, Antonia Maury and Williamina Fleming.
In 1886, the widow of the astronomer Henry Draper endowed HCO, to honor and continue the work that he had done in his lifetime. This resulted in a long-term project to obtain the optical spectra of as many stars as possible and to index and then classify them by spectra. From spectral lines, astronomers can determine not only the element but the temperature and density of that element in the star. (The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving.) Williamina classified 28, 266 spectra of 10,351 stars on 633 plates—by far the most extensive star compilation of the era. (Later editions raised the number of entries to over 300,000.)
Williamina also served as the observatory’s production manager: writing, editing, and proofreading research papers, annual reports, and data tables, as well as the voluminous Annals. In her personal journal, she lamented the conflicting demands on her time: “If one could only go on and on with original work…, life would be a most beautiful dream; but you…use most of your available time preparing the work of others for publication.”
During this time, Williamina was determined to find a simpler and more straightforward way to this process, and devised a system for classifying stars according to the relative amount of hydrogen observed in their spectra, known as the Pickering-Fleming system. Stars showing hydrogen as the most abundant element were classified A; those of hydrogen as the second-most abundant element, B; and so on.
In 1890, the HCO published the first Henry Draper Catalog that over 10,000 stars classified. Willamina organized thousands of photographs by telescope, making it possible to compare recorded plates. After eight years, Harvard appointed her as the first woman to hold the position of Curator of Astronomical Photographs.
In 1893, at the World’s Fair in Chicago, Williamina gave a persuasive talk, “A Field for Woman’s Work in Astronomy” that vigorously promoted the hiring of female assistant in the field. She emphasized that giving women more opportunities would lead to equality, highlighting that culturally constructed sex differences in this area were not biologically sound.
The women of the Harvard Computers were renowned during their lifetimes, but their fame dwindled in the following century. In 2015, Lindsay Smith Zrull, curator of the Plate Stacks at Harvard, began wot work on cataloguing and digitizing the astronomical plates. She discovered 118 boxes, each of which contained 20-30 notebooks. Lindsay recognized the importance of the work, even though it fell outside her area of expertise, and was determined to preserving and making the material accessible. She contacted the librarians at the Harvard-Smithsonian Center for Astrophysics in order to do so. They were delighted to accommodate and housed the work, enabling a full text search. The director, Diana Bouquin, explained: “if you search for Williamina Fleming, you’re not going to just find a mention of her in a publication where she wasn’t the author of her work. You’re going to find her work.”
During her career, Willamina discovered 10 novae, 59 gaseous nebulae, and over 300 variable stars, plus the iconic Horsehead Nebula in Orion. She also recognized the existence of hot, Earth-sized stars later dubbed white dwarfs. The Legacy of Williminia Fleming lives on.
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