Institute of Astronomy

Professor Roger Griffin has died at the age of 85.

Published on 01/03/2021 

(Photograph Credit: Richard Griffin)

Professor Roger Griffin has died at the age of 85.

Professor Roger Griffin spent most of his professional career as an astronomer at Cambridge University, with the exception of a short postdoctoral position at the Mount Wilson and Palomar Observatories in California. 

Returning from California in 1962, he started to work with the 36-inch reflecting telescope, which remains on the IoA site to this day. Roger’s PhD was on narrow-band stellar spectroscopy, working with Prof. Roderick Olivier Redman. Over the years, Roger developed new techniques which would allow him to measure the radial velocity of stars more accurately than previously possible.

Astronomers first started to measure the radial velocity of objects (how fast things are moving towards us or away from us) in the 1860s, but, as Roger noted, the original method was “fundamentally inefficient”. The spectrum of the star you were interested in was analysed by measuring the Doppler shift of the spectral lines to give the stellar velocity. As Roger pointed out, this “involves recording separately many hundreds, often thousands, of independent elements of the spectrum”. 

In 1967, Roger published his classic paper “A Photoelectric Radial-Velocity Spectrometer” (ApJ, 148, 465), and changed the way astronomers measured velocities forever. His brilliant idea was to cross-correlate the stellar spectrum in real time with a ‘coded mask’ -- essentially a high-contrast negative version of a normal star’s spectrum. 

This method allowed for better sensitivity, and far more accurate measurements, than ever before. After some initial resistance, the astronomical community embraced Roger’s new technique -- and the rest is history. As Roger himself put it, in modern astronomy “nobody would dream of measuring velocities in any other way”. 

The technique pioneered by Roger has been used in almost every area of astronomy, from binary stars to black holes to extrasolar planets. The first exoplanet ever found orbiting a distant star, 51 Pegasus b, was discovered using Roger’s method. When Prof. Didier Queloz (the co-discoverer of this exoplanet, and winner of the 2019 Nobel Prize) started his professorship in Cambridge, he asked for an office overlooking the 36-inch telescope, where Roger developed his technique decades earlier. 

In the decades since Roger began his work, he continued to use the 36-inch telescope to measure the radial velocities of stars. He published his results in every single issue of the journal The Observatory, in his long-running series “Spectroscopic Binary Orbits from Photoelectric Radial Velocities”. By 2019 this series had reached paper number 265, making this one of the longest running series of scientific papers of all time. 

Roger was an integral part of Cambridge astronomy for more than 60 years. Indeed, his astronomical career predates the Institute of Astronomy itself, which formed in 1972. In 1980, he was awarded the Jackson-Gwilt Medal by the Royal Astronomical Society (RAS) for his pioneering work on the development of techniques to measure stellar radial velocities. 

In 2015, Roger appeared in the documentary film ‘Star Men’ (https://www.imdb.com/title/tt4481310/). Roger, along with astronomers Donald Lynden-Bell, Neville Woolf, and Wallace Sargent, re-traced a road trip across the American South West taken as young researchers in the 1960s. In the film, Roger reminisces about his early love for all things astronomical: at six years old, seeing the night sky free of light pollution during the Blitz blackout, he decided to dedicate his life to understanding the Universe. Now, 80 years later, much of our hard-won knowledge of the Universe rests on a foundation built by Roger’s pioneering techniques.

He will be greatly missed.

 

Page last updated: 1 March 2021 at 19:18