UT Astronomy Graduate Student Receives Fellowship to Study Exoplanets

The Heising-Simons Foundation has awarded Quang Tran, Ph.D. candidate in The University of Texas at Austin’s Department of Astronomy, one of its eight prestigious 51 Pegasi b Fellowships this year.

Established in 2017, the fellowship provides postdoctoral scientists the opportunity to conduct theoretical, observational, and experimental research in planetary astronomy. From improving our understanding of planetary system formation and evolution, to advancing new technologies for detecting other worlds, fellows make a unique contribution to the field.

“Exoplanet studies are operating on different physical scales and timescales,” Tran says. “Bridging them can provide a much fuller picture of evolution, especially for giant planets that are easier to find—with implications for all planets.”

As a 51 Pegasi b Fellow, Tran will receive $430,000 over three years to conduct independent research on young gas giant exoplanets. Catching them in the act of becoming Hot Jupiters (classes of gas giant exoplanets physically similar to Jupiter with high surface-atmosphere temperatures) would help explain how these massive orbs wind up shockingly close to their parent stars. However, their notoriously active stars mimic and mask planet signals, making it hard to detect them. Tran compares the “noisy” light of these still-developing stars to the sounds of a screaming human baby.

Tran realized he could decrease stellar activity noise significantly by using infrared frequencies. He demonstrated this approach using the Habitable-Zone Planet Finder at UT Austin’s McDonald Observatory, one of the few instruments capable of capturing near-infrared wavelengths at high precision and resolution.

By finding and characterizing more giant exoplanets in this way, Tran aims to clarify the nature and timing of Hot Jupiters as they migrate toward their host stars. What he learns may explain conflicting results across prevailing theories, models, and observations.

“Today we have some advanced techniques and statistical frameworks for modeling exoplanets—but people are getting different results,” explains Tran. “We need more observations and new methods to robustly characterize these systems and understand what might be missing from existing theories and models.”

During his fellowship, Tran will combine existing surveys of young stars to locate enough giant exoplanets in this age range for meaningful comparisons with older planets of similar size and proximity to their host stars. He will also apply his near-infrared radial velocity technique with photometry from the TESS space telescope and statistical modeling to measure the masses for this largest-ever sample of young, giant planets.

In doing so, Tran will extend the timeline of observed planets’ formation backward—and bring forward understanding of their histories, and our own.

Tran will receive a Ph.D. in astronomy from the University of Texas at Austin in Spring 2024. “It’s important to me to appreciate the choice and freedom I have to be a scientist exploring questions about the universe,” Tran says, “and how far I’ve come, thanks to my mom, who brought me to the U.S. at age 3, after she spent seven years in a Malaysian refugee camp escaping the poverty that followed the Vietnam War.”

In Fall 2024, Tran will start a postdoctoral position at Yale University.