Elizabeth Cornwall Tilley

Tilley's doctoral research focused on 59 d Serpentis, a star that appears single to the naked eye but is a quadruple star system.^[4] The system's primary component is itself a spectroscopic triple system, a rare configuration that made it a subject of significant interest.^[2][4]

This primary component consists of a cooler, large G-type giant star and a close binary pair of hot, white A-type main-sequence stars.^[2][4] Tilley's investigation was the first to determine the detailed orbital elements for this triple system.^[5] Her research built upon the 1938 independent discovery by her advisor, Dean B. McLaughlin, and French astronomer R. Tremblot, who first identified three distinct spectra, confirming the system's triple nature.^[2][4]

To conduct her analysis, Tilley utilized spectrograms taken at several major observatories between 1938 and 1942, including the University of Michigan Observatory, Mount Wilson Observatory, and Yerkes Observatory.^[2] Her 1943 paper, published in The Astrophysical Journal, detailed her findings:^[2]

• The G-type giant and the A-type binary pair orbit their common center of mass every 386 days.^[2]
• The two A-type "white twins" orbit each other every 1.85 days.^[2][4]
• The paper provided detailed calculations for the orbits, masses, radii, and inclinations of the stars in the system, concluding that eclipses were unlikely.^[2]

Tilley's findings were presented at a meeting of the American Astronomical Society in Cambridge, Massachusetts, in May 1943 and were reported on in The New York Times.^[5] The report highlighted that 59 d Serpentis was one of only a few known cases where three spectra were visible from a star system and the only one at the time for which the system's details had been fully determined.^[4]

Elizabeth Cornwall Tilley received her Ph.D. from the University of Michigan in 1943.^[1] Her 1943 publication, "A Spectrographic Study of the Triple System in 59 d Serpentis," remains a key reference for the 59 Serpentis system.^[2]

According to a 1954 National Register of Scientific and Technical Personnel compiled by the American Institute of Physics, Tilley reported her professional status as "retired" by November 1954.^[6]