Julia Santos defended her PhD on July 2, 2025, and was awarded the title of Doctor of Philosophy cum laude from Leiden University.

Her doctoral research focused on the ices that coat interstellar dust grains, where rich chemistry unfolds to produce the molecular feedstock for planets and potentially life. Her thesis centered on molecules containing carbon, hydrogen, oxygen, and sulfur---four key biogenic elements essential to life-related processes. By combining astronomical observations, which trace the molecular history of interstellar space, with laboratory experiments that reveal the mechanisms behind these observed outcomes, Julia’s work provides a holistic view of the origins and fate of interstellar molecules.

Major results of her thesis are the discovery of several new chemical pathways for organic molecule formation in ices, including the confirmation of a route to methanol that challenges a 20-year-old paradigm. She also investigated ice sublimation triggered by exothermic reactions and protostellar heating, and how the latter affects the snowlines of key species. Together, these findings offer new insight into the chemical evolution of interstellar ices and the inventory of molecules delivered to forming planetesimals.

Julia will continue to study the role of ices in the chemical evolution of star- and planet-forming regions as a 51 Pegasi b Fellow at Harvard University.