A 2017 University of Hawaiʻi at Mānoa Institute for Astronomy (IfA) doctoral graduate has been awarded the Robert J. Trumpler Award from the Astronomical Society of the Pacific. The distinction recognizes a recent PhD thesis considered unusually important to astronomy. Benjamin J. “BJ” Fulton is the fourth IfA graduate to receive the award in the past six years.
Fulton’s landmark doctoral dissertation focused on the discovery and categorization of extrasolar planets, particularly smaller planets between the sizes of Earth and Neptune. Fulton analyzed data from the W.M. Keck Observatory for more than 1,300 planets that were initially discovered by NASA’s Kepler Space Telescope. The primary result of Fulton’s thesis, under the advisement of Professor Andrew Howard, is the discovery that the size distribution of extrasolar planets has a gap separating two types: super-Earths with sizes smaller than about one-and-a-half Earth diameters, and sub-Neptunes with sizes two-to three-Earth diameters.
The interpretation of this gap is that it represents the separation of rocky planets from low-mass planets with gas atmospheres, and its discovery has already sparked numerous theoretical and observational studies. Fulton’s paper announcing this gap garnered immediate attention. A measure of how important this effect is on the field is that it has been given a name, the Fulton Gap.
One nominator stated the Fulton Gap “will undoubtedly be in undergraduate and graduate textbooks. It demonstrates a natural division among planets, on par with the division between rocky planets, ice giants and gas giants in our Solar System.”
Fulton is currently a staff scientist at the NASA Exoplanet Science Institute, based at the Infrared Processing and Analysis Center, a science and data center for astronomy at Caltech. He serves as the deputy project scientist for the NASA-National Science Foundation Exoplanet Observational Research program, which funds and operates the NEID spectrograph, an instrument with the ability to discover Earth-like planets orbiting the nearest stars.
This award continues a remarkable streak for graduates of IfA’s PhD program who have won four awards in the past six years. The previous recipients were H. Jabran Zahid in 2015, who is now a Clay Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics; Brendan P. Bowler in 2014, who is now an assistant professor in the Department of Astronomy at the University of Texas at Austin; and Emily Levesque in 2012, an assistant professor in the University of Washington’s astronomy department.
