UChicago: Supernova shrapnel found in meteorite

[bystander]

Supernova shrapnel found in meteorite
University of Chicago | 09 Sept 2010

Scientists have identified the microscopic shrapnel of a nearby star that exploded just before or during the birth of the solar system 4.5 billion years ago.

Faint traces of the supernova, found in a meteorite, account for the mysterious variations in the chemical fingerprint of chromium found from one planet and meteorite to another. University of Chicago cosmochemist Nicolas Dauphas and eight co–authors report their finding in the late Sept. 10, 2010 issue of the Astrophysical Journal.

Scientists formerly believed that chromium 54 and other elements and their isotopic variations became evenly spread throughout the cloud of gas and dust that collapsed to form the solar system. “It was a very well–mixed soup,” said Bradley Meyer, a professor of astronomy and astrophysics at Clemson University who was not a co–author of the study. “But it looks like some of the ingredients got in there and didn’t get completely homogenized, and that’s a pretty interesting result.”

Scientists have known for four decades that a supernova probably occurred approximately 4.5 billion years ago, possibly triggering the birth of the sun. Their evidence: traces of aluminum 26 and iron 60, two short–lived isotopes found in meteorites but not on Earth.

These isotopes could have come from a type II supernova, caused by the core–collapse of a massive star. “It seems likely that at least one massive star contributed material to the solar system or what was going to become the solar system shortly before its birth,” Meyer said.

Researchers have already extracted many type II supernova grains from meteorites, but never from a type IA supernova. The latter type involves the explosion of a small but extremely dense white–dwarf star in a binary system, one in which two stars orbit each other. It should now be possible to determine which type of supernova contributed the chromium 54 to the Orgueil meteorite.

Neutron-rich Chromium Isotope Anomalies in Supernova Nanoparticles - N Dauphas et al

• Astrophysical Journal 720(2) 1577 (10 Sept 2010) DOI: 10.1088/0004-637X/720/2/1577
  arXiv.org > astro-ph > arXiv:1007.4016 > 22 Jul 2010

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Supernova shrapnel found in meteorite
University of Chicago | 09 Sept 2010

Researchers have already extracted many type II supernova grains from meteorites, but never from a type IA supernova. The latter type involves the explosion of a small but extremely dense white–dwarf star in a binary system, one in which two stars orbit each other. It should now be possible to determine which type of supernova contributed the chromium 54 to the Orgueil meteorite.

Original painting the Orgueil meteorite

<<It fell on May 14, 1864, a few minutes after 8 pm, near Orgueil in southern France. About 20 stones fell over an area of several square miles. A specimen of the meteorite was analyzed that same year by François Stanislaus Clöez, professor of chemistry at the Muséum d'Histoire Naturelle, who focused on the organic matter found in this meteorite. He wrote that it contained carbon, hydrogen, and oxygen, and its composition was very similar to peat from the Somme valley or to the lignite of Ringkohl near Kassel. An intense scientific discussion ensued, continuing into the 1870s, as to whether the organic matter might have a biological origin.

Orgueil is one of five known meteorites belonging to the CI chondrite group, this being the largest (14 kg). This group is remarkable for having a composition that is essentially identical to that of the sun, excluding gaseous elements like hydrogen and helium.

Because of its extraordinarily primitive composition and relatively large mass, Orgueil is one of the most-studied meteorites. One notable discovery in Orgueil was a high concentration of isotopically anomalous xenon called "xenon-HL". The carrier of this gas is extremely fine-grained diamond dust that is older than the solar system itself, known as presolar grains.

In 1962, Nagy et al. announced the discovery of 'organised elements' embedded in the Orgueil meteorite that were purportedly biological structures of extraterrestrial origin. These elements were subsequently shown to be either pollen (including that of ragwort) and fungal spores (Fitch & Anders, 1963) that had contaminated the sample, or crystals of the mineral olivine.

• The hoax

In 1965, a fragment of the Orgueil meteorite, kept in a sealed glass jar in Montauban since its discovery, was found to have a seed capsule embedded in it, whilst the original glassy layer on the outside remained apparently undisturbed. Despite great initial excitement, the seed capsule was shown to be that of a European rush, glued into the fragment and camouflaged using coal dust. The outer "fusion layer" was in fact glue. Whilst the perpetrator is unknown, it is thought that the hoax was aimed at influencing 19th century debate on spontaneous generation by demonstrating the transformation of inorganic to biological matter.>>

Chromium 54

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• There's hold up at Montauban;
  The Somme has seen better wars.
  The ragwort pollen in Orgueil
  Is backed up with fungal spores.
  The "fusion layer" is just glue;
  The European rush is new.
  Chromium 54, Where Are You?