Jesse Han (GSAS Astronomy '25) wins the 2026 Robert J. Trumpler Award
Dr. Jesse Han (GSAS Astronomy '25) has won the 2026 Robert J. Trumpler Award!
Awarded by the Astronomical Society of the Pacific, the Trumpler Award recognizes a recent PhD thesis that is considered unusually important to astronomy. Jesse defended his PhD here less than one year ago, in September 2025.
The Robert J. Trumpler Award is presented to a recent recipient of a PhD degree whose research is considered unusually important to astronomy. Dr. Jesse Han is the recipient of the 2026 Robert J. Trumpler Award, having received his doctorate in astronomy and physics from Harvard University and is currently a Stanford Science Fellow at Stanford University. Han’s thesis research was directed towards understanding the formation and evolution of galaxies across cosmic time using the knowledge to interpret observations of the structure of the Milky Way. Han’s significant recent contributions to Galactic astronomy were summarized by one of his professors, who wrote, “I regard Jesse’s thesis work as the most impactful. He has solved multiple long-standing puzzles and has presented a new, comprehensive view of the outer Galaxy.”
Astronomers have long observed that the Milky Way’s disk is warped and bent, but the cause was unknown. Through innovative observation and simulation, Han discovered that the surrounding dark matter and star halos are tilted. In his landmark paper, "A tilted dark halo origin of the Galactic disk warp and flare, “he showed that the gravitational pull from a tiled and “doubly broken” halo drives the disk’s warp.” His findings, published in Nature Astronomy, exposed crucial clues on how hidden dark matter shapes our Galaxy, suggesting it may have experienced a dramatic merger with a smaller galaxy some 10 billion years ago.
Another outcome of Han’s research was the discovery that a significant fraction of hyper-velocity stars (HVSs) around the Milky Way originated in the Large Magellanic Cloud (LMC), a dwarf galaxy orbiting the Milky Way. Using high-precision 3D trajectory data from the Gaia space telescope, Han tracked these fast-moving stars backward in time to discover almost half of the HVS paths led straight back to the Large Magellanic Cloud (LMC). The only model that explains the speed, quantity, and position of these stars is the presence of a supermassive black hole hidden inside the LMC. Scientists previously did not know if dwarf galaxies like the LMC could host supermassive black holes. Proving one exists in the LMC reshapes our understanding of galaxy formation, black hole evolution, and how galaxies interact. A collaborator and colleague observed that “Jesse is now leading several observation efforts to directly identify this black hole, which would be a spectacular result, making it the second closest known supermassive black hole, behind only the one in the center of the Milky Way.”
Han is an emerging leader in the field, taking the initiative in graduate school to lead an important NASA white paper to use to use the Nancy Grace Roman Space Telescope and create a near infrared map of the entire sky. The project - the Next-generation All-sky Near-infrared Community SurveY (NANCY) is a collaboration with over 200 scientists. Han’s team is building widespread partnerships across ground and space-based observatories to establish NANCY as shared scientific infrastructure. In describing Han’s leadership, a close colleague wrote, “I expect the work to have a long-lasting impact on the field, and I fully expect Jesse to become a leader in Galactic dynamics and near-field cosmology.”
Han has already published numerous papers, received awards and distinctions, and served as Principle Investigator (PI) and co-PI on seven projects utilizing Chandra and Hubble. He was featured in a short segment with NPR’s All Things Considered about uncovering evidence of a supermassive black hole in our neighboring Large Magellanic Galaxy. Alongside his academic career, Han is also an accomplished rock and ice climber, and active musician in the Bay Area. Sourec: see the announcement page.