Olson is best known for his innovative analysis of eclipsing and mass-transferring binary systems using model stellar atmospheres with computationally derived opacities.
Edward (Ed) Cooper Olson died on Monday, July 13, 2020. He was 90.
Ed will be most remembered for his pioneering work utilizing computational derived opacities and model stellar atmospheres to analyze eclipsing binaries and mass-transfer binary systems. Much of his work required detailed monitoring observations and stellar atmospheric modeling, which allowed him to study spectra and light curves, and producing many papers cited more than 50 times. His love of binary stars lasted long after his retirement.
Ed was born June 7, 1930 in Worcester, Massachusetts, to Nils Olaf Olson and Marion Elizabeth (Cooper) Olson. He attended Classical High School and Worcester Polytechnic Institute (WPI), graduating from WPI in 1952 with a B.S. in Physics. After earning his B.S., he was accepted for the Ph.D. program in Astronomy at Indiana University but was drafted into the U.S. Army before he could attend. The Korean War ended while he was in Basic Training, and he was sent to White Sands Proving Ground to serve with other physics college graduates working on the army’s missile program. He learned to love the food and the Southwest while there.
After his discharge, he went to Bloomington, Indiana (two years late) for graduate school. There he met Henry Norris Russell’s granddaughter Margaret. Married in 1959 and with a new Ph.D. in 1961, Ed taught astronomy and did research, first at Smith College in Northampton, Massachusetts, next at Rensselaer Polytechnic Institute in Troy, New York, and from 1966 until his retirement in 1994 at the University of Illinois at Urbana-Champaign.
Most of Ed’s research focused on deciphering the observed photometric and spectral properties of binary stars. For example, he measured the rotational velocities of 40 component stars in 29 binary systems, most of which were eclipsing binaries with the hotter component's spectral type ranging from F0 to O9 . He showed that stars in binary systems rotate slower than single stars of the same spectral type and that synchronous rotation can be achieved relatively rapidly.
A very useful and well-cited work of Ed’s was the calibration of Strömgren ubvy photometry, carried out by comparing photoelectric observations of Strömgren color indices (u-b) and (b-y) with those calculated from stellar model atmospheres , later revised . He obtained four-color (ubvy) photoelectric photometry for 92 late-type stars and showed the luminosity and [Fe/H] metallicity effects in color-color diagrams .
In the mid-1970’s, Ed shifted his focus from eclipsing binaries to the much more complex mass-transfer binary systems. He observed mass transfer events and period changes of U Cephei, and made a detailed analysis of effects of its accretion disk, hot spot, and mass flow stream on primary eclipse light curves . This marked the beginning of his dedication to Algol-type binaries, even long past his retirement.
Ed monitored 10 Algol-like binaries and found the eclipse-to-eclipse variations are related to instabilities in the lobe-filling subgiants . He further observed 108 primary eclipses of 16 short-period Algols and saw photometric disturbances related to episodic mass transfer, similar to those seen in U Cephei that can be explained by equatorial bulges, streams, and hot spots .
He continued his research on Algols for over 20 years after he retired from the University of Illinois in 1994. His last masterpiece was a comprehensive analysis of the long-period Algol eclipsing binary RX Geminorum, in collaboration with his friend and collaborator Paul Etzel. They analyzed photometric and spectroscopic data, modeled them with a non-LTE disk code, and suggested the presence of a perturbing third body in this binary system .
Ed leaves his wife, Margaret, two sons, Eric and Jeff (Becky), seven grandchildren (Jennifer, Amy, Russell, Quanan, Nathan, Liliana, and Laurie), three step-grandchildren (Raco, Kandise and Kasaja), and four great-grandchildren (Kolten, Khloe, Waylon, and Carsen).
Ed and Margaret Olson moved into The Neighborhood in Rio Rancho in September 2017. While in Independent Living, Ed enjoyed the Fitness Center, taking exercise classes and walking daily on the treadmill. He hiked weekends along the Rio Grande with his son Eric. Great-grandsons and grandchildren visited them. But Alzheimer’s was taking a toll. In June 2019, Ed moved into Memory Care. Ed passed away on Monday July 13, 2020 in NIRR’s Memory Care Unit, which had wonderful and caring staff.
Ed loved hiking, mountain climbing, cross-country skiing, classical music, reading and photography. He was a longtime Sierra Club member. He did astronomy research on the tops of mountains, climbed the Grand Teton, was stung on his foot by a sting ray in Cabo San Lucas, and traveled to the Canadian Rockies, England, Scotland, Italy, Hawaii and Alaska. He played a homemade PVC pipe bass flute on the stage of the Krannert Musical Center in Urbana, and he rode his bicycle 3.5 miles each way to work most of the days of the 50 plus years he worked in the University of Illinois Astronomy Department.
See also Olson’s AstroGen entry.