Parisa Mostafavi, winner of the 2020 Fred L. Scarf Award
Parisa Mostafavi

Parisa Mostafavi completed an outstanding Ph.D. thesis titled “Shock waves and nonlinear plasma waves mediated by pickup ions and energetic particles” in the Department of Space Science at the University of Alabama in Huntsville. A question of long-standing interest is how energetic particles, whether solar energetic particles, pickup ions, or anomalous and galactic cosmic rays, mediate the structure of shock waves as they are energized via diffusive shock acceleration. The problem is important to space weather because some very fast, strong interplanetary shocks are completely dominated by the energy of the accelerated particles, often rendering the character of the shock quite different from classical magnetohydrodynamic shocks. Parisa examined the foundations of shock structure, developing a theoretical description that accounted for the energetic particles and their coupled feedbacks to the background thermal plasma and fields. Parisa’s model described accurately the structure of the Voyager 2 observed TS-3 heliospheric termination shock crossing, including the preferential heating of pickup ions. In another major contribution, Parisa pointed out, much to the surprise of many in the community, that the very local interstellar medium (VLISM) is collisional on scales of interest to the Voyager observations, unlike the collisionless interplanetary medium. Hence, collisional dissipative processes are important for weak VLISM shocks. The puzzling observations of unusually broad weak shocks transmitted from the solar wind into the VLISM observed by Voyager 1 were explained by Parisa as a natural consequence of collisional dissipation (primarily the collisional heat flux associated with proton–proton collisions). Parisa was able to describe the structure, scalings, and properties of the interstellar shocks observed by Voyager 1. This paper is establishing a new paradigm for the physics of the VLISM. Parisa’s thesis resulted in nine refereed journal papers, of which she was first author on four, and seven refereed conference papers.

—Gary P. Zank, Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville


I would like to thank the award committee and the AGU Space Physics and Aeronomy section for selecting me for this year’s Fred L. Scarf Award. I am deeply honored to receive it. I am grateful to many people in my life. Specifically, I would like to express my deepest gratitude to my Ph.D. adviser, Dr. Gary Zank, for his continuous support. He always generously found time in his busy schedule to help me whenever I needed it. He gave me excellent guidance on my research and taught me to work hard. During the last year of my Ph.D., I had the privilege of working with the space physics group at Princeton University. I am thankful to Dr. Dave McComas for this opportunity. He taught me how to work through research challenges and use my time wisely. I would like to extend my thanks to Dr. Len Burlaga for supporting my work and giving me the opportunity to collaborate with him. I want to thank Dr. Peter Hunana, Dr. Eric Zirnstein, and Dr. Laxman Adhikari for their valuable discussions. I also owe many thanks to my instructors and colleagues in the space physics department of the University of Alabama in Huntsville. Finally, I wish to thank my family for their unconditional love and support. Now I am a postdoc working at the Johns Hopkins University Applied Physics Lab and looking forward to many more new research experiences.

—Parisa Mostafavi, Johns Hopkins University Applied Physics Laboratory, Laurel, Md.


(2021), Mostafavi receives 2020 Fred L. Scarf Award, Eos, 102, Published on 07 July 2021.

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