Jonathan Gagné
Sagan Fellow

Jonathan Gagne

Research Interests

Brown dwarfs; young moving groups; direct-imaging of exoplanets; near-infrared spectroscopy; detection of exoplanets by radial velocity measurements


B.S., Physics, Univeresity of Montreal, 2010
M.A., Astrophysics, University of Montreal, 2012
Ph.D., Astrophysics, University of Montreal, 2015

Contact & Links


Jonathan Gagne
Artist's conception of the isolated planetary-mass object PSO J318.5-22, which is the first confirmed object with a mass well below the deuterium-burning limit and no host star. Credit: NASA/JPL-Caltech

Jonathan Gagné grew up in a small town north of Montreal and moved there to study Physics. He became interested in his current research area while he was an undergrad at Université de Montréal and had the chance to complete a summer internship related to the direct imaging of exoplanets and brown dwarf surveys under the direction of René Doyon.

Gagné's Ph.D. project, which consisted of the search for isolated brown dwarfs in young moving groups under the direction of Doyon and David Lafreniére, represented a great marriage of these two topics. After submitting his Ph.D. thesis in April 2015, Gagné will now bring his project to the next level during his Sagan Fellowship at the Carnegie Institution for Science by identifying young brown dwarfs with only a few times the mass of Jupiter and exploring the connection between their atmospheres and those of giant exoplanets.

He will extend the successful survey he led during his Ph.D. thesis to locate the elusive coldest, isolated planetary-mass members of young moving groups. Gagné will use the suite of high-end instruments at Las Campanas Observatory in Chile to characterize these discoveries with a parallax program, optical and near-infrared low and mid-resolution spectroscopy and high-precision photometric measurements. This research will allow him to explore the connection between the atmospheres of brown dwarfs and those of giant exoplanets, and will put strong constraints on the initial mass function down to a few times the mass of Jupiter, hence testing the recent prediction that the spatial density of isolated jupiter-mass objects is twice as large as that of stars.

Gagné was named the winner of the 2016 J. S. Plaskett Medal, which is given annually to a Ph.D. graduate from a Canadian university who is judged to have submitted the most outstanding doctoral thesis in astronomy or astrophysics in the preceding two calendar years.  It is sponsored jointly by the Canadian Astronomical Society (CASCA) and the Royal Astronomical Society of Canada.