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Antonia Maury

Antonia Maury

American astronomer Antonia Maury (1866-1952) was notable as much for refusing to submit to obscurity as she was for her valuable research. The importance of her work was not fully recognized until late in her life. At the age of 77, Maury was awarded the Annie J. Cannon Prize by the American Astronomical Society.

Maury was a woman ahead of her time. She was driven by her convictions rather than the agenda set by the scientific community. Maury demanded to be acknowledged as the author of her work, a gesture commonly denied to contemporary women scientists. Spending long hours in tedious and painstaking observation of the spectral emissions of stars, she invented her own system of star classification that was ignored as cumbersome by her Harvard contemporaries. However, her system was the stepping stone to discoveries that constitute the very foundation of modern stellar astrophysics.

A Family of Intellectuals

Antonia Maury was born in Cold-Spring-on Hudson, New York, on March 21, 1866, to a distinguished family She was the older daughter of the Reverend Mytton Maury and his wife Virginia Draper. Her maternal uncle was the respected Harvard astronomer, Henry Draper. Historian and physicist, John William Draper, was her maternal grandfather. Her father's ancestors were French Huguenots, while her mother was descended from Portuguese nobility.

Maury was educated at home with her brother and younger sister until her teenage years. Her father, an Episcopalian minister, was her primary tutor. She went on to study at Vassar and graduated with a bachelor's degree in 1887, earning honors in astronomy and physics.

The Henry Draper Project

When Henry Draper died, astronomer Edward Charles Pickering of the Harvard Observatory took over his project of cataloging and classifying stars according to their spectra. The light from a star, when viewed through a prism and magnified appears as a band of colors punctuated by darker bands. These are termed spectral lines, and represent a distinctive fingerprint for each star. Analysis of these lines provides insights into the star's temperature, chemical composition, and motion.

A year after her graduation, Maury joined Pickering's staff of women "computers" to help complete the immense work of observing and classifying stars for the Draper catalog. As director of the Harvard Observatory since 1876, Pickering was the first to include women on his staff, as volunteers and salaried assistants. This, however, appears to have been more an act of economic pragmatism than progressive-mindedness. In spite of the low pay, averaging about $10.50 per week, or about 25 cents an hour, applications from women flooded in from all over the world. Harlow Shapley, a director of the observatory after Pickering, was quoted as saying: "Luckily Harvard College was swarming with cheap assistants; that was how we got things done." The entire job of classifying some 250,000 stars took 40 years to complete. It could not have been accomplished without the group of women whom some alluded to as "Pickering's Harem." Foremost among them were Antonia Maury, Williamina Fleming, and Annie Cannon.

Brought Individuality to Project

Maury's first assignment for Pickering was to determine the orbital period of the spectroscopic binary, Zeta Ursae Majoris, also called Mizar, first discovered by Pickering in 1887. Binaries are stars that orbit so close to each other that they cannot be detected except by a spectroscope. When examined, the spectral lines regularly shift back and forth as the stars revolve around each other. In 1889, Maury independently discovered the second binary, Beta Aurigae and determined its orbital period. Binaries continued to fascinate Maury throughout her career.

Maury's major assignment for the Draper catalog was to observe a group of selected bright northern stars. These were photographed with a more powerful telescope fitted with additional prisms. As she enlarged and studied the spectra under a microscope, they proved much more complex than had ever been previously realized. Fleming had devised an alphabetical system of classification where stars were grouped into alphabetical categories: OBAFGKM— which was remembered through the mnemonic "Oh Be A Fine Girl, Kiss Me." Maury felt this system to be too simplistic, so she replaced it with her own system of 22 groups based on a sequence of descending temperature.

Within each of these groups, however, Maury noticed that two stars having the same pattern of lines and color were displaying differences in line width and sharpness. She decided to introduce three further subdivisions that recognized these features, believing them to signal some property yet to be discovered.

Resented for her Independence

Maury's system brought her into direct conflict with Pickering, who saw no need for the entire project to fall behind schedule so that she could carry out her painstakingly meticulous width and sharpness measurements. Maury was always inclined to solve problems or puzzles that she encountered, and tended to fall behind the schedule that Pickering set for data collection. Finally, the original thinker in Maury could no longer endure Pickering's tunnel vision. She left his group in 1892 without completing the study.

Cornerstone of Astrophysics

One person did take notice of Maury's classification. Although less than fluent in the English language, the noted Danish astrophysicist Ejnar Hertzprung objected strongly to the omission of Maury's classification in the completed catalog. He wrote: "In my opinion the separation by Antonia Maury of the c-and ac stars is the most important advancement in stellar classification since the trials by Vogel and Secchi. To neglect the c-properties in solar spectra, I think, is nearly the same thing as if the zoologist, who had detected the deciding differences between a whale and a fish, would continue in classifying them together."

Maury's work was vital in Hertzprung's formulation which came to be known as the Hertzprung-Russel diagram. This opened the door to an entirely new level of understanding the characteristics and evolution of stars. In 1905, Hertzprung had noticed that some red stars were very bright, while others seemed faint. He was sure that these two types of stars would show differences in their spectra. Of all the catalogs published, only Maury's classification provided the distinction that he was looking for.

Although Pickering continued to downplay the importance of Maury's work, her contribution to spectral analysis was finally acknowledged in 1922. That year, the International Astronomical Union modified its official classification system based on Annie Cannon's system to include the prefix c-to a certain spectral type defined by narrow and sharp lines.

Determined to Receive Recognition

After leaving the Harvard Observatory, Maury continued to work intermittently on the project. Pickering urged her to complete the work or agree to turn it over to someone else. Though she was eager to finish, both for the sake of her reputation and to honor the memory of her late uncle, Maury had one basic condition: she would have to be acknowledged unambiguously as its author. In a letter to Pickering, she said: "I do not think it is fair that I should pass the work into other hands until it can stand as work done by me. I worked out the theory at the cost of much thought and elaborate comparison and I think that I should have full credit for my theory of the relations of the star spectra and also for my theories in regard to Beta Lyrae."

Pickering wrote back somewhat coldly that it was the regular practice of the Observatory to acknowledge authors of "particular portions." Maury would not settle for the standard acknowledgement. In the end, she got her wish. Her catalog, appearing in volume 28 of the Harvard Annals in 1897 was the first issue to have the name of a woman on the title page. Maury's study was based on some 4,800 photographs. 681 northern stars were classified according to her system.

Continued to Examine Binaries

Although Maury did not return to Harvard for over a decade after the publication of her catalog, she continued to research spectroscopic binary stars. She turned her attention to the complex spectroscopic binary, Beta Lyrae, investigating it over many years. Maury is said to have examined close to 300 spectra of this star. She published her conclusions in a treatise published in the Harvard Annals in 1933.

Maury held various teaching positions in the 1890s. She taught first at the Gilman School in Cambridge, Massachusetts and later at Miss Mason's school in Tarrytown, New York. She also delivered lectures on astronomy at Cornell and elsewhere, both to professional audiences and laypersons. She returned to Harvard in 1918 as an adjunct professor. Pickering died in 1919 and Maury found herself able to work better with his successor, Harlow Shapley. She continued to examine the puzzling spectra of Beta Lyrae until her official retirement in 1948.

Maury was also an accomplished ornithologist and a passionate conservationist who fought to save western redwood forests when they were being fed to sawmills to meet the wartime lumber requirements. She was a member of the American Astronomical Society, the Royal Astronomical Society, and the National Audubon Society. For several years after her retirement, Maury was curator of the Draper Park Museum at Hastings-on Hudson. She died on January 8, 1952, at a hospital in Dobbs Ferry, New York.

Cecilia Payne-Gaposchkin, who began work at the Harvard Observatory in 1923, discussed her impressions of Maury: "Of course, I only knew her when she was old. I was very fond of her, but she just talked and talked and talked and talked. You couldn't do any work because she wanted to talk so much. It was just she needed an outlet; she needed to discuss. Nobody had ever listened to her, nobody had ever responded to her scientific questionings, I think."

Further Reading

Bailey, Martha J., American Women in Science, A Biographical Dictionary, ABC-CLIO Inc., 1994

Biographical Encyclopedia of Scientists, edited by John Daintith, Sarah Mitchell, Elizabeth Tootill, and Derek Gjertsen, Market House Books Ltd., 1994

Crees, Mary R.S. and Thomas M. Crees, Ladies in the Laboratory? American and British Women in Science, 1800-1900, Scarecrow Press, 1998

Hathaway, Nancy, The Friendly Guide to the Universe, Penguin Books, 1995

Women of Science, Righting the Record, edited by G. Kass-Simon and Patricia Farnes, Indiana University Press, 1990

Sky and Telescope, March 1952.

Astronomical Society of the Pacific, History of Women in Astronomy, (October 27, 1999)

Franknoi, Andrew and Ruth Freitag, Women in Astronomy: An Introductory Bibliography, (November 2, 1999)

SJSU Virtual Museum, Antonia Caetana de Paiva Pereira Maury,, (October 21, 1999). □

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Maury, Antonia Caetana De Paiva Pereira


(b. Cold Spring-on-Hudson, New York, 21 March 1866; d. Dobbs Ferry, New York, 8 January 1952)


Antonia Maury was the daughter of Mytton and Virginia Draper Maury, a niece of Henry Draper, and granddaughter of John William Draper, a pioneer in the application of photography to astronomy. Her background was rich and varied, for her father was a naturalist and editor of a geographical magazine, as well as a professional minister. Although she worked chiefly as an astronomer, she was also an active ornithologist. Her sister, Carlota Joaquina Maury (1874–1938), became a paleontologist speciallizing in Venezuelan and Brazilian stratigraphy.

In 1890 Williamina Fleming’s Draper Catalogue of Stellar Spectra was published, with an initial classification of more than 10,000 stars. To Miss Maury was assigned a more detailed study of the brighter stars, made possible by placing three or four prisms in front of the eleven-inch Draper refractor (a telescope originally owned by her uncle, Henry Draper, and given to Harvard by his widow). Miss Maury soon concluded that the single spectral sequence of the Draper Catalogue was inadequate for representing all the observed peculiarities. In particular, for stars of the early spectral groups she assumed the existence of three collateral divisions (designated a, b, and c ) characterized by the width and distinctness of their lines. In her system, a stars had normal lines, b, hazy lines, and c, sharp lines. Intermediate cases were designated ab or ac. Her catalogue, based on an examination of about 4,800 photographs, included her elaborate classification of 681 bright stars of the northern skies (Annals of Harvard College Observatory, 28 pt. [1896]).

College Observatory, 28 , pt. 1 [1896]).

Shortly after graduating from Vassar in 1887, Miss Maury became an assistant at the Harvard College Observatory, where during the next eight years she carried out her most perceptive and creative research. At that time the observatory director, Edward C. Pickering, was engaged in a program of stellar spectroscopy, and he had just found that the spectral lines of the star Mizar were double on one plate but single on others. Additional photogaphs established Mizar as the first spectroscopic binary, and Miss Maury was the first to determine its period, 104 days. In 1889 she herself discovered the second such star, Beta Aurigae, with a period of about four days.

Miss Maury’s painstaking classifications enabled Ejnar Hertzsprung to verify his discovery of two distinct varieties of stars—dwarfs (divisions a and b) and gaints (c). Unfortunately, Hertzsprung’s interpretation was scarcely exploited at Harvard and in later work there, the a, b, c, distinction was largely ignored in favor of the more elementary Draper system, as extended by Annie Jump Cannon. This led Hertzsprung to write to Pickering (22 July 1908):

In my opinion the separation by Antonia C. Maury of the c-and ac-stars is the most important advancement in stellar classification since the trials by Vogel and Secchi… To neglect the c-properties in classifying stellar spectra, I think, is nearly the same thing as if the zoologist, who has detected the deciding differences between a whale and a fish, would continue in classifying them together.

Miss Maury’s temperament was little suited to the often tedious observatory routine, and as early as 1891 her connection with Harvard became an on-again off-again affair. After her paper on spectral classification was finally published, for several years she lectured on astronomy in various cities; between lectures she accepted private pupils and an occasional teaching position. In 1908 she returned to Harvard Observatory as a research associate, resuming her earlier studies of spectroscopic binaries. She spent many years investigating the complex spectrum of the binary Beta Lyrae, details of which were published in the Annals of Harvard College Observatory, 84 , no. 8 (1933). After retiring in 1935, at the age of sixty-nine, she served for several years as curator of the Draper Park Museum at Hastings-on-Hudson, New York, paying nearly annual visits to the Harvard Observatory to examine the current spectra of Beta Lyrae.


Miss Maury’s chief publications are noted in the text. A short obituary by Dorrit Hoffleit appears in Sky and Telescope, 11 (1952), 106. The best source is Bessie Zaban Jones and Lyle Gifford Boyd, The Harvard College Observatory (Cambridge, 1971), 395–400; see also Solon I Bailey, The History and Work of Harvard Observatory, 1839–1927 (New York, 1931).

Owen Gingerich

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"Maury, Antonia Caetana De Paiva Pereira." Complete Dictionary of Scientific Biography. . 28 Apr. 2017 <>.

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