Sachiko Amari, Washington University in St. Louis, USA

Recipient of the 2021 Urey Award

Sachiko Amari is a research professor of Physics at Washington University in St. Louis, USA. She is also a visiting scientist at Geochemical Research Center at The University of Tokyo, Japan. She is a fellow of The Meteoritical Society since 2000 and a member of Japan Geoscience Union.

Research Statement

“I study primitive meteorites to probe the history of the early solar system and beyond. Two of my main research interests are presolar grains and volatiles in the solar system.

Presolar grains are dust grains formed in the stellar outflow or ejecta and remain largely intact in meteorites and other extra-terrestrial materials. The study of these presolar grains has opened up a new field of astronomy. By examining these grains using various instruments, we have learned nucleosynthesis in stars, mixing in stellar ejecta, temporal variation of isotopes and elements in the Galaxy, and grain condensation in stellar ejecta.

I, with my colleagues, have separated carbonaceous presolar grains from meteorites using chemical and physical methods, and study isotopic ratios of those grains using secondary ion mass spectrometry to better understand processes in stars and stellar outflow. Of the carbonaceous presolar grains, my focus in recent years has been graphite grains. We learned that two major stellar sources of graphite grains are asymptotic giant branch stars and supernovae. In collaboration with astrophysicists, we investigate nucleosynthetic processes in these stars from isotopic signatures of graphite grains.

I am also interested in the origin of volatiles, especially noble gases, in the solar system. The majority of heavy noble gases in primitive meteorites are contained in a very small portion of carbonaceous material named Q for quintessence. Ureilites are known for their igneous features yet they contain abundant noble gases whose elemental and isotopic patterns are strikingly similar to those of Q. I am very much interested in how noble gases that are very similar to each other were trapped into two kinds of meteorites, which experienced very different processes in the early solar system.”

Additional information and a list of publications can be found here.