Stardust From The Murchison Meteorite

The Murchison meteorite, which fell in Victoria, Australia in 1969, is one of the most well-studied meteorites in the world. Weighing over 700 kilograms, it is a carbonaceous chondrite, a type of meteorite rich in organic compounds and water. The Murchison meteorite has provided scientists with a unique window into the early solar system, offering insights into the formation and evolution of our cosmic neighborhood. One of the most fascinating aspects of the Murchison meteorite is the presence of stardust, also known as presolar grains, which are remnants of ancient stars that predate our solar system.

Introduction to Stardust

Stardust is composed of tiny particles that were forged in the hearts of ancient stars through nuclear reactions. These particles, typically measuring only a few micrometers in size, were ejected into space when their parent stars exploded as supernovae. Over time, they were incorporated into the solar nebula, a cloud of gas and dust that eventually gave rise to our solar system. The presence of stardust in meteorites like Murchison provides strong evidence for the interstellar origin of some of the material that makes up our solar system.

Types of Presolar Grains

Scientists have identified several types of presolar grains in the Murchison meteorite, including silicon carbide (SiC), graphite, and diamond. These grains have distinct isotopic signatures that reflect the conditions under which they formed. For example, silicon carbide grains from the Murchison meteorite have been found to have unusual ratios of silicon and carbon isotopes, which suggest that they originated from asymptotic giant branch (AGB) stars. These stars are thought to have played a key role in the formation of presolar grains through their mass loss processes.

Analysis of Stardust from the Murchison Meteorite

Scientists have used a range of techniques to analyze the stardust from the Murchison meteorite, including mass spectrometry and scanning electron microscopy. These techniques have allowed researchers to determine the chemical composition and structural properties of the presolar grains. For example, studies have shown that the silicon carbide grains from the Murchison meteorite have a crystalline structure and are composed of a mixture of isotopically anomalous silicon and carbon.

Implications for the Formation of the Solar System

The presence of stardust in the Murchison meteorite has significant implications for our understanding of the formation of the solar system. The fact that these grains are older than the solar system itself suggests that the material that made up the solar system was inherited from previous generations of stars. This idea is supported by the presence of other presolar materials in the Murchison meteorite, including ammonia and water. These findings suggest that the solar system formed from a complex mixture of interstellar material and primitive solar nebula gas and dust.

• The Murchison meteorite contains a range of presolar grains, including silicon carbide, graphite, and diamond.
• These grains have distinct isotopic signatures that reflect the conditions under which they formed.
• The presence of stardust in the Murchison meteorite provides strong evidence for the interstellar origin of some of the material that makes up our solar system.