Clues to the Processing of Dust around Stars

Sept. 27, 2019

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Artist impression of solar system formation.
Gemini Observatory/AURA artwork by Lynette Cook Artist impression of solar system formation. Presolar grains are tiny, solid grains of primitive solar system material that originated before the formation of the Sun. They have been found in many places, including interplanetary dust, meteorites, and even samples from the comet Wild-2 that were returned to Earth by NASA's Stardust mission.

In the laboratory, a team of scientists supported in part by the NASA Astrobiology Program have studied simulated presolar grains to better understand how these materials are affected by heat and radiation in space. Presolar grains originate from a time before the Sun formed, and include a range of materials. These ancient grains can provide clues about the origin and evolution of stars and solar systems.

In the study, researchers focused on silicates and oxides. Small particles containing silicates and oxides can be found swirling around stars, and provide details about the how dust in the parent star originated and was processed over time.

In the laboratory, the team irradiated and heated analogue materials of olivine and hibonite. Hibonite is a rare mineral on Earth but can be found in presolar grains contained in some primitive meteorites. Olivine is a more common mineral on our planet, and is a primary component of the Earth’s mantle. However, olivine can also be found in some meteorites, and has been identified on Mars, the Moon, around young stars, and in other locations beyond the Earth.

The team crushed synthetic hibonite and olivine into a fine-grained powder. After heating and irradiation, the material was then analyzed to determine any changes to the surface morphologies or atomic structures. Understanding how the grains are altered can help scientists interpret data collected from such materials, and to distinguish between features that are original to the material and those that are generated over time as grains interact with the space environment.

A potential interstellar dust track (circled) in Stardust’s aerogel collector.IMAGE CREDIT: UC BERKELEY/ANDREW WESTPHAL.

The study, “In situ Ion Irradiation and Heating Experiments in the Transmission Electron Microscope: Simulations of Dust Processing in Circumstellar Environments,” was published in Microscopy and Microanalysis. The work was supported by the Nexus for Exoplanet System Science (NExSS).  NExSS is a NASA  research coordination network supported in part by the  NASA Astrobiology Program. This program element is shared between NASA’s Planetary Science Division (PSD) and the Astrophysics Division. This research is a critical part of NASA’s work to understand the Universe, advance human exploration, and inspire the next generation. As NASA’s Artemis program moves forward with human exploration of the Moon, the search for life on other worlds remains a top priority for the agency.

NASA Astrobiology