Patrick Thaddeus

PUBLISHED: 19 JUNE 2017 | VOLUME: 1 | ARTICLE NUMBER: 0170 obituary Patrick Thaddeus A pioneer in the field of astrochemistry, Patrick Thaddeus discovered dozens of exotic molecules in space and helped revolutionize our view of the interstellar medium and star formation. atrick Thaddeus did more than anyone telescope operating from a rooftop just a else to demonstrate, as he was fond few hundred yards from Broadway. After Pof saying, that chemistry was not a over two decades of steady mapping with provincial subject that stopped five miles this instrument and a near-duplicate one above our heads. As a pioneer in the field that they installed in Chile in 1982, Pat and of astrochemistry, his elegant laboratory his students obtained what is still today work provided ironclad identifications the most extensive and widely used survey of hundreds of new molecules of of the molecular Milky Way. More than astronomical interest, and his observational 40 years later, both telescopes continue to programme discovered about one-sixth yield important scientific results, including of the ~200 molecules known to exist in the discovery over the past decade of two space. His early recognition that carbon THOMAS DAME new spiral arm features of the Galaxy. monoxide would be an excellent tracer of A total of 24 PhD dissertations have the cold dense regions of space led directly been written based on observations or to the discovery of giant molecular clouds instrumental work with the two telescopes. and a revolution in our understanding of In 1986, Pat, along with several the interstellar medium and star formation. postdocs, students, and an engineer, loaded Pat was born on 6 June 1932 in Arden, seven tractor trailers with laboratory Delaware, and passed away peacefully on equipment and their 4-foot telescope THOMAS DAME 28 April 2017 in Cambridge, Massachusetts. and headed north to the Center for Apparently the small village of Arden did Patrick Thaddeus (1932–2017) Astrophysics (CfA), where he would work not provide enough of the rich intellectual for another three decades as a professor stimulation that Pat would savour of astronomy and applied physics at throughout his adult life, for as a youth he of the CN radical. With his prior optical Harvard, and as a senior space scientist was known as a bit of a scamp. On seeing experience limited to his handmade with the Smithsonian Astrophysical Pat’s name in Scientific American years telescope, Pat relished learning the now Observatory. The spectroscopy laboratory later, one of his teachers remarked that he arcane techniques of optical spectroscopy, that he set up at the CfA has been one of would sooner have expected to see him in the baking and cutting of glass plates to fit the most productive in terms of scientific prison. His interests in instrumentation their curved holders, the careful guiding output and impact. Hundreds of exotic and astronomy were likely sparked by of the telescope for hours on end, the or ‘non-terrestrial’ molecules have been his decision as a teenager to take on the development of plates while immersed in detected there, and nearly one-tenth of arduous task of building a reflecting total darkness and pungent odours. Based these were discovered in space based on telescope from scratch. on over 100 hours of observations with the highly precise laboratory frequencies. They Pat obtained a bachelor’s degree in Lick 120-inch telescope, he and a student include species such as C2H, C4H, SiC2, and physics from the University of Delaware were able to measure a temperature of cyclic C3H2, which are now widely used in 1953, and a master’s in theoretical 2.78 ± 0.10 K for the CMB at 2.6 mm. as chemical tracers of star formation. The physics as a Fulbright scholar at Oxford, On 27 September 1974, Pat met in his spectacular discovery of negatively charged UK, in 1955. He was then taken on by office with John Mather, then his postdoc, molecules in 2006 overturned conventional Professor Charles Townes at Columbia Michael Hauser, David Wilkinson, and wisdom that such anions were too fragile to University around the time Townes was a few others to discuss the possibility of exist in space. completing his Nobel-prize-winning building a satellite to measure both the Pat Thaddeus will be remembered research on maser and laser emission. Pat’s spectrum and possible spatial fluctuations by his colleagues as much more than a own thesis work, completed in 1960, was of the CMB. This seminal meeting led brilliant scientist. As a teacher, he could on the subject of beam maser spectroscopy. directly to the COBE satellite project and a illuminate the most obscure concepts with Pat would spend most of the next Nobel Prize for Mather. Ultimately, COBE’s vivid analogies enabled by his own deep 26 years in New York City, as a professor of measurement of the CMB at 2.6 mm was understanding. Hearing Pat give a scientific physics at Columbia and, simultaneously, as within 0.6σ of the value Pat had measured lecture, you felt as if he were grabbing you a research physicist at the NASA Goddard 18 years earlier using CN. by the collar to convey his excitement. He Institute for Space Studies. After preliminary CO mapping with was a superb politician in the best sense of Following the discovery of the cosmic his students revealed that molecular the word. When grappling with a difficult microwave background (CMB) in 1965, regions in space were far larger than problem, he would often dash to the phone Pat saw the opportunity to measure the expected, Pat saw the need for a small but to chat with the world’s expert, invariably CMB near the peak of its 3 K blackbody dedicated telescope to map these regions. a close friend. He had very high standards curve using the optical absorption lines In 1974 he and his group built a 4-foot for scientific exposition. Even now I NATURE ASTRONOMY 1, 0170 (2017) | DOI: 10.1038/s41550-017-0170 | www.nature.com/natureastronomy 1 ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. obituary feel a sense of unease that these words mushroom species around his Berkshire THOMAS DAME will be published without first passing home, or the magnificent flight of the Thomas Dame is at the Harvard–Smithsonian below the vigorous red pen of Professor wandering albatross. Center for Astrophysics, 60 Garden Street, Thaddeus. He was a true intellectual with Pat Thaddeus loved what he did, and he Cambridge, Massachusetts 02138, USA. boundless interests. At a dinner with was extremely good at it. In that sense he He worked with Patrick Thaddeus for Pat, you were as likely to learn about the was a very fortunate person, as were we all 40 years as a student, colleague and friend. philosophy of quantum mechanics, the for having known him. ❐ e-mail: [email protected] 2 NATURE ASTRONOMY 1, 0170 (2017) | DOI: 10.1038/s41550-017-0170 | www.nature.com/natureastronomy ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. .

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