|Born||15 May 1857|
|Died||21 May 1911 (aged 54)|
Williamina Paton Stevens Fleming (15 May 1857 – 21 May 1911) was a Scottish astronomer active in the United States. During her career, she helped develop a common designation system for stars and cataloged thousands of stars and other astronomical phenomena. Among several career achievements that advanced astronomy, Fleming is noted for her discovery of the Horsehead Nebula in 1888.
Williamina Paton Stevens was born in Dundee, Scotland on 15 May 1857, to Mary Walker and Robert Stevens, a carver and gilder. There, in 1877, she married James Orr Fleming, an accountant and widower, also of Dundee. She worked as a teacher a short time before the couple emigrated to Boston, Massachusetts, US, when she was 21. The couple had one son, Edward P. Fleming.
After she and her young son were abandoned by her husband, Williamina Fleming worked as a maid in the home of Professor Edward Charles Pickering, who was director of the Harvard College Observatory.
Pickering's wife Elizabeth recommended Williamina as having talents beyond custodial and maternal arts, and in 1879 Pickering hired Fleming to conduct part-time administrative work at the observatory. In 1881, Pickering invited Fleming to formally join the HCO and taught her how to analyze stellar spectra. She became one of the founding members of the Harvard Computers, an all-women cadre of human computers hired by Pickering to compute mathematical classifications and edit the observatory's publications.
In 1886, Mary Anna Draper, the wealthy widow of astronomer Henry Draper, started the Henry Draper Memorial to fund the HCO's research. In response, the HCO began work on the first Henry Draper Catalog, a long-term project to obtain the optical spectra of as many stars as possible and to index and classify stars by spectra.
Fleming was placed in charge of the Draper Catalog project. A disagreement soon developed as to how to best classify the stars. The analysis had been started by Nettie Farrar, but she left a few months later to be married. Antonia Maury advocated for a complex classification scheme. Fleming, however, wanted a much more simple, straightforward approach.
The latest Harvard College Observatory images contained photographed spectra of stars that extended into the ultraviolet range, which allowed much more accurate classifications than recording spectra by hand through an instrument at night. Fleming 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.
Later, her colleague Annie Jump Cannon reordered the classification system based upon the surface temperature of stars, resulting in the Harvard system for classifying stars that is still in use today.
As a result of years of work by their female computer team, the HCO published the first Henry Draper Catalog in 1890, a catalog with more than 10,000 stars classified according to their spectrum. The majority of these classifications were done by Fleming. Fleming also made it possible to go back and compare recorded plates, by organizing thousands of photographs by telescope along with other identifying factors. In 1898, she was appointed Curator of Astronomical Photographs at Harvard, the first woman to hold the position.
During her career, Fleming discovered a total of 59 gaseous nebulae, over 310 variable stars, and 10 novae.
Most notably, in 1888, Fleming discovered the Horsehead Nebula on a telescope-photogrammetry plate made by astronomer W. H. Pickering, brother of E.C. Pickering. She described the bright nebula (later known as IC 434) as having "a semicircular indentation 5 minutes in diameter 30 minutes south of Zeta Orionis". Subsequent professional publications neglected to give credit to Fleming for the discovery. The first Dreyer Index Catalogue omitted Fleming's name from the list of contributors having then discovered sky objects at Harvard, attributing the entire work merely to "Pickering". However, by the time the second Dreyer Index Catalogue was published in 1908, Fleming and her female colleagues at the HCO were sufficiently well-known and received proper credit for their discoveries.
Fleming is also credited with the discovery of the first white dwarf:
The first person who knew of the existence of white dwarfs was Mrs. Fleming; the next two, an hour or two later, Professor E. C. Pickering and I. With characteristic generosity, Pickering had volunteered to have the spectra of the stars which I had observed for parallax looked up on the Harvard plates. All those of faint absolute magnitude turned out to be of class G or later. Moved with curiosity I asked him about the companion of 40 Eridani. Characteristically, again, he telephoned to Mrs. Fleming who reported within an hour or so, that it was of Class A.— Henry Norris Russell
Fleming published her discovery of white dwarf stars in 1910. Her other notable publications include A Photographic Study of Variable Stars (1907), a list of 222 variable stars she had discovered; and Spectra and Photographic Magnitudes of Stars in Standard Regions (1911).
She died of pneumonia in Boston on 21 May 1911.
Fleming openly advocated for other women in the sciences in her talk "A Field for Woman's Work in Astronomy" at the 1893 World's Fair in Chicago, where she openly promoted the hiring of female assistants in astronomy. Her speech suggested she agreed with the prevailing idea that women were inferior, but felt that, if given greater opportunities, they would be able to become equals; in other words, the sex differences in this regard were more culturally constructed than biologically grounded.
In 1906, she was made an honorary member of the Royal Astronomical Society of London, the first Scottish woman to be so honored. Soon after she was appointed honorary fellow in astronomy of Wellesley College. Shortly before her death the Astronomical Society of Mexico [es] awarded her the Guadalupe Almendaro medal for her discovery of new stars.
The women of the Harvard Computers were famous during their lifetimes, but were largely forgotten in the following century. In 2015, Lindsay Smith Zrull, curator of Harvard's Plate Stacks collection, was working to catalog and digitize the astronomical plates for DASCH and discovered about 118 boxes, each containing 20 to 30 notebooks, from women computers and early Harvard astronomers. She realized that the 2,500+ volumes were outside the scope of her work with DASCH, but wanted to see the material preserved and made accessible. Smith Zrull reached out to librarians at the Harvard-Smithsonian Center for Astrophysics.
In response, the Wolbach Library launched Project PHaEDRA (Preserving Harvard's Early Data and Research in Astronomy). Daina Bouquin, Wolbach's Head Librarian, explained that the objective is to enable full-text search of the research: "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."
In July 2017, Harvard-Smithsonian Center for Astrophysics's Wolbach Library unveiled a display showcasing Fleming's work, including the log book containing the Horsehead Nebula discovery. The library has dozens of volumes of Fleming's work in its PHaEDRA collection.
As of August 2017[update], about 200 of over 2,500 volumes had been transcribed. The task is expected to take years to fully complete. Some of the notebooks are listed via the Smithsonian Digital Volunteers Web site, which encourages volunteers to transcribe them.