During a summer internship at European Southern Observatory (ESO), Yapeng Zhang witnessed the discovery of exoplanet Proxima Centauri b in a habitable zone orbiting the star nearest Earth’s sun. Mesmerized, she has been exploring the mysteries of planetary science ever since. Today, Yapeng traces exoplanets back to their origins by examining their present atmospheric properties and comparing key differences across object classes and locations. As the universe of known exoplanets continues to diversify, a nuanced understanding of their formation depends on a growing mix of observational probes—and Yapeng has already contributed substantially in this regard. Her pioneering work led to the first detection of minor carbon isotopologues (carbon-bearing molecules with differing numbers of neutrons) within an exoplanet atmosphere. This capability opens up exciting new opportunities to understand how such bodies form—as the location of a planet’s inception, its gas or solid growth processes, and its atmospheric loss are all expected to impact the ratios of isotopes present.

During her fellowship, Yapeng will greatly deepen and expand her research. Using the newly upgraded high-resolution spectrograph at ESO’s Very Large Telescope, she will conduct a precision survey of isotopic and elemental ratios across 20 super-Jupiters, free-floating planets, and brown dwarfs. She will also double this sample size, leveraging high-resolution observations captured by state-of-the-art Keck Observatory instruments. In the process, Yapeng expects to identify patterns that help unravel the paths of exoplanet formation and explain the astronomic conditions resulting in young gas giants versus brown dwarfs. Yapeng will receive a Ph.D. in astronomy from Leiden University in Summer 2023.

“Low-mass brown dwarfs and super-Jupiters have similar masses, but they probably formed differently… the first collapsing downward, the other possibly building bottom-up. Because we detected and measured very different isotopologue ratios in these objects, we realized this could be a useful tracer for formation pathways.”