Dust grains from the asteroid Ryugu, which is older than our solar system

28Si hotspots. (f) 17O-rich presolar oxide found in the Ryugu A0058-2 matrix. (g)–(h) This O-anomalous presolar grain was found in the less altered area shown in (b). The inlet in (g) shows a δ18O sigma image in which every pixel represents the number of standard deviations from the average values. The grain is probably a presolar silicate as Si is present in the EDX map, and Al was neither detected in the EDX map nor the NanoSIMS ion image, unlike the adjacent spinel (MgAl2O4), purple in color in (h). Credit: The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac83bd”>

Staubkörner vom Asteroiden Ryugu, der älter ist als unser Sonnensystem28Associated with Si hotspots. (f) 17O-rich pre-solar oxide found in matrix Ryugu A0058-2. (g)-(h) This O-anomalous presolar grain was found in the less altered region shown in (b). The inlet in (g) shows a δ180 sigma image in which each pixel represents the number of standard deviations from the mean values. The grain is likely a pre-solar silicate since Si is present in the EDX map and Al was not detected in either the EDX map or the NanoSIMS ion image, in contrast to the neighboring spinel (MgAl2O4 ), violet in (h). Source: The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac83bd” width=”800″ height=”530″/>

(a) Backscattered electron (BSE) image of Ryugu thin section A0058-2. Each black area consists of approximately 20 measured NanoSIMS cards. (b) An area in section C0002 with less altered lithology than the surrounding Ryugu matrix (“clast 1”; BSE image). This region contains Mg-rich olivine, low-Ca pyroxenes, and spinel grains with sizes up to 15 μm (Kawasaki et al. 2022). Two of three O-anomalous grains identified at Ryugu, including a probable pre-solar silicate (g)-(h), were found in this region. (c)–(e) Secondary electron (SE) image of a Ryugu particle pressed in gold foil, in which two presolar SiC grains were detected. The C-anomalous regions, indicated by the white arrows, are clearly associated with 28Si hotspots. (f) 17O-rich pre-solar oxide found in matrix Ryugu A0058-2. (g)-(h) This O-anomalous presolar grain was found in the less altered region shown in (b). The inlet in (g) shows a δ18O-sigma image in which each pixel represents the number of standard deviations from the average values. The grain is likely a pre-solar silicate since Si is present in the EDX map and Al was not detected in either the EDX map or the NanoSIMS ion image, in contrast to the neighboring spinel (MgAl2O4), violet in (h). Recognition: The Letters of the Astrophysical Journal (2022). DOI: 10.3847/2041-8213/ac83bd

An international team of researchers examining dust samples taken by the Hayabusa-2 spacecraft have found that some of its dust grains are older than the solar system. In her article published in The Letters of the Astrophysical Journalthe group describes their analysis of the asteroid dust and what they found.

The Hayabusa-2 spacecraft began its mission back in 2014 when it was launched into space aboard an H-IIA 202 rocket. Four years later he encountered the near-Earth asteroid 162173 Ryugu. After orbiting the asteroid for two years, he descended to its surface and snagged a sample Pop up Dust. Then it exploded and made its way back to Earth.

Located 300 million kilometers from Earth, Ryugu orbits the Sun every 16 months. It has been described as little more than a gravel accumulation, likely made from the debris of several other asteroids. Other research has shown that it probably formed in the outer part of the solar system and has been creeping inward ever since – others as well suggest its dust hints the possibility that Earth’s water came from a similar asteroid.

Ever since the dust sample collected by the probe returned to Earth, pieces of it have been passed around the world to various researchers eager to test it in different ways. In this new attempt, the researchers attempted to determine its age – noting that different types of grains in asteroids like Ryugu come from different types of stars and stellar processes. The ages of the grains in their dust can be identified and dated based on their isotopic signatures.

In examining the Ryugu dust sample, the researchers compared it to grains found in carbonaceous chondrite meteorites found on Earth. They note that only 5% of these meteorites contained grains that predate the formation of the solar system – some of which have been dated as far back as 7 billion years. The researchers found that the dust sample contained grains identical to any others seen in meteorites, showing it predates them too solar system. They note that one in particular, a silicate known to be very easily destroyed, must have been protected from sun damage somehow.


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More information:
Jens Barosch et al, Presolar Stardust on Asteroid Ryugu, The Letters of the Astrophysical Journal (2022). DOI: 10.3847/2041-8213/ac83bd

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Citation: Dust grains of the asteroid Ryugu, which is older than our solar system (2022, August 18), retrieved on August 19, 2022 from https://phys.org/news/2022-08-grains-asteroid-ryugu-older-solar .html

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