The 7 billion-year-old star dust in asteroid hits Earth

Scientists identified the giant rock meteorite that fell to Earth half a century ago containing dust and is believed to be the oldest solid material.

Ancient stellar dust includes particles that existed before the Sun and fired into the universe from dead stars in the final stages of their life cycle. Part of the stellar dust was brought to Earth by the asteroid creating Murchison meteorite , a 100 kg stone weighing on September 28, 1969 near the town of Murchison, Victoria, Australia.

Star dust samples came before the solar system.(Photo: Live Science).

New analysis on 40 dust particles from the Murchison meteorite revealed they have a diverse date. 60% of particles date from 4.6 to 4.9 billion years, about 10% at least over 5.6 billion years. The age is determined at the time the stars explode. Based on the fact that this type of star has a lifespan of 2 to 2.5 billion years, the team estimates that stellar dust is about 7 billion years old, 2.5 billion years earlier than the Solar System.

Despite the abundance of stellar dust in the universe, researchers have never found stellar dust larger than the Sun in rock samples on Earth. That's due to the tectonic plates, volcanic eruptions and other planetary processes that heat and transform all ancient star dust, according to lead researcher Philipp Heck, director of meteorite research. and polar region at Field Natural History Museum in Chicago.

When large meteors formed like asteroids creating Murchison meteorite, they enveloped the ancient stellar dust particles. But unlike the continually moving planets, the meteorite is an inert mass from the nebula and kept it from that, preventing star dust from melting into another form of mineral, Heck explained.

Most stellar dust is about 1 micron or smaller. But the dust particles the team analyzed were much larger, between 2 and 30 microns long. " We call them 'pebbles'. We can observe them with an optical microscope," Heck said.

In the study, Heck and colleagues examined 40 " pebbles" from the Murchison meteorite. They crushed pieces of meteorite, then small acids help dissolve minerals and silicate. The researchers use dating technology based on the exposure of dust particles to cosmic rays in the interstellar journey that takes billions of years.

In space, high-energy particles emanate from various sources, colliding and piercing solid objects flying through. By measuring the amount of different elements in the dust particle, the team can estimate the time it is exposed to cosmic rays.

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