Incoming Postdoc, Outgoing Grad Awarded 51 Pegasi B Fellowships
Samuel Yee, a soon-to-be postdoctoral fellow at the Center for Astrophysics | Harvard & Smithsonian (CfA), and Juliana García-Mejía, a doctoral student at the CfA, have been awarded 51 Pegasi b Fellowships from the Heising-Simons Foundation. Yee and Garcia-Mejia are two of only eight students in the nation to receive the prestigious award.
The fellowship will provide up to $415,000 in support for Yee and García-Mejía to conduct independent research in planetary astronomy over the next three years.
Established in 2017, the 51 Pegasi b Fellowship is named for the first exoplanet discovered orbiting a Sun-like star. The fellowship supports the growing field of planetary astronomy, which focuses on objects within and beyond our solar system. From improving the understanding of planetary system formation and evolution to advancing new technologies for detecting other worlds, 51 Pegasi b Fellows make a unique contribution to the field of astronomy.
Learn more about the two fellowships recipients below.
Juliana García-Mejía
Host Institution: Massachusetts Institute of Technology
Growing up in Colombia, Juliana García-Mejía split time between helping to repair equipment at her maternal family's fitness business and gazing up at the stars from her paternal family's coffee farm. She credits this eclectic upbringing with preparing her, in part, to be the principal investigator of the Tierras Observatory, based at the Fred Lawrence Whipple Observatory in Amado, Arizona.
"I'm an instrument builder at heart," García-Mejía says. "I love spending time in the lab figuring out how to translate a scientific question into an instrument that can help to answer it. The coolest question out there for me continues to be, 'Is there life elsewhere in the universe?'"
While earning her Ph.D. at Harvard, Juliana was charged with transforming a once-shuttered 1.3-m telescope for new service. She led all aspects of the design, construction, and recommissioning of Tierras, an exquisitely precise, fully automated photometer that accelerates the discovery of terrestrial exoplanets orbiting small, cool stars called M-dwarfs. The improvements García-Mejía led include a novel optical system that allows the telescope to image a larger swath of sky, a custom filter that declutters atmospheric effects like water vapor from images, and a robotic mode to capture data night after night.
"Most Ph.D. students do not get the opportunity to build something as comprehensively as I did," she says. "It was high risk, but it made my eureka moment — seeing that first image after Tierras came online — so special."
During her fellowship at MIT, García-Mejía will use Tierras to find Earth-like planets around M-dwarf stars, undertake a systematic search for moons and rings around exoplanets, and study the stars themselves to understand their impact on the planets they host. In tandem with this work, Juliana will design a next-generation, high-resolution instrument with the goal of one day enabling oxygen detection in exoplanet atmospheres. Her research will bolster the census of newfound worlds —prime targets for the James Webb Space Telescope to probe for signs of habitability.
García-Mejía will receive a Ph.D. in astronomy and astrophysics from Harvard University in May 2023.
Samuel Yee
Host Institution: Harvard University
During an undergraduate summer research program at the California Institute of Technology, Samuel Yee helped develop software that has since been used by astronomers around the world and cited in hundreds of scholarly works. Now pursuing his Ph.D. in astrophysics, Yee is preparing to deliver another breakout resource for planetary science: He leads the TESS (Transiting Exoplanet Survey Satellite) Grand Unified Hot Jupiter Survey, a project using data from NASA’s TESS spacecraft, as well as spectroscopic observations from many more ground-based telescopes, to find and characterize hundreds of these gas giants.
While Hot Jupiters were among the first exoplanets discovered decades ago, the way they formed remains perplexing. During his fellowship at the CfA, Yee will combine new planetary data from his survey with that of previously known planets to build the largest-ever sample of Hot Jupiters, which may shed further light on their formation.
"Although we know of hundreds of Hot Jupiters, they were discovered by many different surveys, so it was difficult to study their statistics," Yee explains. "In the past, the largest demographic sample of Hot Jupiters available had just 40 planets. With a sample size of 400, we're going to do ten times better. New telescopes like the European Space Agency's Gaia spacecraft and NASA's JWST will allow us to study the planets in this sample efficiently and in greater detail."
With this statistically useful sample, Yee will study the distribution of Hot Jupiter radii, periods, and other properties with respect to those of their stellar hosts, as well as the geometric architecture of their solar systems and whether they include additional planets. Demographic trends surfaced through Yee’s study are expected to provide clues as to when and how these exoplanets came to orbit their parent stars so closely — and establish fertile ground for further inquiry.
Yee will receive a Ph.D. in astrophysics from Princeton University in the summer of 2023.
Learn more about the 51 Pegasi b Fellowship at www.51pegasib.org.
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About the Heising-Simons Foundation
The Heising-Simons Foundation is a family foundation based in Los Altos and San Francisco, California. The Foundation works with its many partners to advance sustainable solutions in climate and clean energy, enable groundbreaking research in science, enhance the education of our youngest learners, and support human rights for all people. Learn more at www.hsfoundation.org.