On 14 November 2013, Dr. Paola D'Alessio Vessuri, researcher at the Center for Radioastronomy and Astrophysics (CRyA) of the National Autonomous University of Mexico (UNAM), passed away, after an eight and a half year battle with cancer.

Paola was born in Oxford, England, on July 30, 1964. She completed her undergraduate studies in physics at the Central University and the Research Center for Astronomy of Venezuela, and earned her master's and doctoral degrees at UNAM's Institute of Astronomy (IA), which she joined as a researcher in 1996. She was a visiting researcher at the Harvard-Smithsonian Center for Astrophysics (CfA) in Boston and the American Museum of Natural History in New York, and in 2001 she returned to Mexico and joined the Morelia Unit of the IA, that shortly after would become the CRyA.

Paola was a world-renowned expert in the study of protoplanetary disks. For over 15 years, starting with her doctoral thesis, Paola's calculations have defined the state of the art in models of protoplanetary disks. She pioneered the development of detailed models that have allowed astronomers to infer the physical properties of the disks from a comparison with observational data. Among her most important results, Paola proved the concentration and growth of solid particles in protoplanetary disks, processes that constitute the first stage of planet formation. Together with her collaborators, she also discovered protoplanetary disks with gaps produced by giant planets in formation.

Paola had fruitful collaborations with many research groups, among others, in the CRyA and IA, the University of Michigan, the CfA, the University of Rochester, Indiana University, Cornell, the NASA Jet Propulsion Lab, the Institute of Astrophysics of Andalucía and the Herschel Science Center. Her models have been applied to observations of over 500 disks obtained with both space and ground-based telescopes.

She published 100 refereed articles that have received almost 7000 citations, and continue to get about 700 citations per year. She also published nearly 50 outreach articles. Although she directed relatively few theses, she contributed to the development of many young astronomers both in Mexico and abroad.

Paola was recognized with mult's and doctoral studies; the 1997 Weizmann Prize to the best science doctoral thesis, awarded by the Mexican Academy of Sciences, and the Recognition Sor Juana Inés de la Cruz, given to outstanding UNAM academics, in 2006. For the high impact of her articles, she received the 2009 Scopus Award from Elsevier/CONACyT, and the Recognition Thomson Reuters-Cinvestav 2009. In 2010, she received the State Prize of Science and Technology of the Government of the State of Michoacán.

Paola was a brilliant researcher; her premature departure is a huge loss for astronomy internationally. And yet, those of us who were privileged to share her life and work will remember above all her humanity, her kindness, her joy, and her strength in adversity.

Rosa A. González, Stan Kurtz, and Susana Lizano