image: Matthew Nixon, Class of 2025 51 Pegasi b Fellow. Courtesy photo
Credit: Heising-Simons Foundation
Arizona State University continues its rapid rise in planetary astronomy, welcoming two new 51 Pegasi b Fellows to its exoplanet research team in fall 2025. The Heising-Simons Foundation awarded the prestigious postdoctoral fellowships to Matthew Nixon and Sagnick Mukherjee, who will carry out independent research at ASU’s School of Earth and Space Exploration.
This is a major milestone for ASU: With a quarter of all fellows selected in just two years of eligibility, the university has rapidly emerged as a national leader in exoplanet science and a hub for early-career talent.
“I am thrilled to welcome Matt and Sagnick to ASU,” said Luis Welbanks, a 51 Pegasi b Fellow who will be beginning a faculty appointment at the school this fall. “Their arrival marks a major milestone as we continue building one of the most vibrant exoplanet teams in the country. As I launch a new research group, I am focused on bringing together the brightest minds to tackle the field’s most pressing questions. Sagnick and Matt bring exceptional creativity, technical skill and collaborative drive — and I am excited to mentor them as we push the boundaries of what is possible in exoplanet science.”
Established in 2017, the 51 Pegasi b Fellowship supports eight early-career scientists each year to advance the study of planetary systems. Fellows pursue novel work across a range of topics, from cosmochemistry to modeling of planetary interiors to observational campaigns with telescopes such as the James Webb Space Telescope.
Expanding the frontier of sub-Neptune science
Matthew Nixon, a 2023 PhD graduate from the University of Cambridge and currently a postdoctoral associate at the University of Maryland, focuses on the atmospheres and interiors of sub-Neptune exoplanets. At ASU, he will lead several JWST programs, including the characterization of HD 86226 c, a hot sub-Neptune potentially harboring a long-lived magma ocean, and a campaign to resolve long-standing questions surrounding the atmosphere of WASP-39 b, a benchmark giant planet.
“The School of Earth and Space Exploration has a vast range of expertise, from state-of-the-art atmospheric observations to high-pressure geophysics,” Nixon said. “I am incredibly excited to work across disciplines here to help unravel the mysteries of sub-Neptune planets.”
Building new models for mysterious worlds
Mukherjee, a PhD candidate at the University of California, Santa Cruz, brings expertise in exoplanet atmospheres and brown dwarfs. His research at ASU will focus on developing new theoretical models to probe the structure and evolution of sub-Neptunes using JWST data.
“ASU’s leadership in exoplanet science — across theory, observation and lab work — makes it an ideal environment for my research,” Mukherjee said. “I am especially eager to collaborate with and be mentored by Dr. Welbanks and Dr. Line, whose work I deeply admire. The interdisciplinary culture at SESE will allow me to connect with planetary scientists, geochemists and others whose insights are vital for understanding these still-mysterious worlds.”
Growing a high-impact exoplanet team
Mukherjee’s arrival, alongside Nixon’s, reflects ASU’s deliberate investment in building an interdisciplinary research environment that fosters both scientific depth and collaboration. With strengths spanning theoretical modeling, telescope operations, laboratory experiments and machine learning, SESE is shaping a new generation of planetary scientists equipped to lead in the decades ahead.
“We are excited to have Matt and Sagnick join our exoplanet team,” said Mike Line, associate professor at the School of Earth and Space Exploration. “Their expertise complements our existing strengths in observation, modeling and theory. Having four fellows in just our first two years of eligibility reflects SESE’s leadership in recruiting top talent in exoplanet research.”
Their selection not only underscores the caliber of researchers choosing ASU, but also aligns with the national scientific priorities outlined in the Exoplanet Science Strategy, the Astro2020 Decadal survey and the ExEP Science Gap List — including the urgent need for new models and observations of small exoplanets, atmospheric retrieval techniques and interior structure analysis to support future missions like the Habitable Worlds Observatory.
“It is a testament to the growing strength of our interdisciplinary astronomy, planetary and cosmochemistry programs that ASU continues to attract 51 Pegasi b Fellows,” said Meenakshi Wadhwa, Foundation and Regents Professor and director of the School of Earth and Space Exploration. “We are proud to support these talented scientists as they pursue high-impact research in exoplanet science.”
By welcoming Nixon and Mukherjee, ASU affirms its leadership in shaping the future of exoplanet research — one that answers the most profound questions about planet formation, atmospheric evolution and the potential for life beyond Earth.
The 51 Pegasi b Fellowship provides up to three years of financial support for independent research, including an annual stipend, research funds and professional development.