A 92-year-old Ohio State University (OSU) astronomer who claimed to be the longest-publishing in his field, and was known for publishing a premier atlas of stellar-spectra "signatures," has died.

In coming weeks, the OSU Department of Astronomy plans to scatter the ashes of Philip C. Keenan at the grounds of the Perkins Observatory in Delaware, Ohio, where the Pennsylvania native did much of his work and enjoyed gardening.

That atlas, based on what came to be called the "MKK System" after its authors, was a fundamental reference and framework for astronomers to come.

Keenan could identify any type of star with a quick glance at its spectrum, his colleagues said.

In 1976, after a career that started at the University of Chicago and led him to work as a physicist -- first with the U.S. Navy Bureau of Ordnance, then to decades of work at Ohio State -- Keenan retired. He continued his research through 1999 as an emeritus professor.

"I think it would have been a mistake to stop my work as soon as I retired," Keenan reportedly said. "I think I would've gotten bored. Work helps keep you alive, and there's much work to be done.

Keenan's most recent collaborator, Cecilia Barnbaum of Valdosta State University in Georgia, offered a couple anecdotes that expressed Keenan's unfailing dedication and humor.

Barnbaum says that she and Keenan met in 1995 after he asked her to help him create a new atlas of stars with atmospheres rich in carbon. When she agreed, Keenan, then 87, climbed into his car and drove for six days from Columbus, Ohio to the National Radar Astronomy Observatory in Charlottesville, Virginia to introduce himself in person.

"Now I want you to understand that I fully expect to drop dead any day now," Keenan said wryly, according to Barnbaum. "So I might not be here to finish the atlas."

Actually, he did finish the atlas, and its publication in the Journal of the Astronomical Society of the Pacific in 1997 inspired Keenan to call himself the "longest-publishing" astronomer.

In a recent meeting at a restaurant, where Keenan and Barnbaum discussed their latest project, Keenan ordered a hamburger, choosing to ignore stomach problems that limited his meals to thin soup and bread..

"He took a bite," Barnbaum recalled, "and said, 'I'm sure this is going to kill me, but it's going to be worth it.'"

Keenan's most recent work with Barnbaum was published in the Astrophysical Journal in 1999.

Keenan was born on March 31, 1908. He received his Bachelor and Master's degrees from the University of Arizona. He then earned his Ph.D. from the University of Chicago, where he continued as an instructor until 1942.

At Ohio State, Keenan focused on stars cooler than our sun, with spectra containing a large number of atomic and molecular features. Such stars are in advanced states of their evolution, said Patrick Osmer, OSU Astronomy Department chair, and eject their outer atmosphere into space as they complete their life cycles. That process contributes to the evolution of galaxies like our Milky Way.

Keenan accepted the current focus in astronomy on black holes and active galaxies, but he hoped that older lines of work on classifying stars with advanced technology would continue.

Keenan never married. When asked why, he joked that he thought no one would put up with him. However his life remained full with research, student mentoring and hobbies such as riding horses through the plains of Texas with his former colleague, Daniel Popper of the University of California, Los Angeles. Popper died last year.

"Philip's dedication to astronomy, his long career and his extensive knowledge of the field were an inspiration to the members of the Ohio State Astronomy Department," Osmer said, "and especially to the students who knew him."