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Supernova Dust Fell to Earth in Antarctic Meteorites

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Antarctic meteorite

A section of the LaPaz Icefield 031117 meteorite, courtesy of NASA.

Two primitive meteorites collected in Antarctica appear to contain grains of silica—the stuff of quartz and sand—forged in an ancient supernova that predates the birth of the solar system. In fact, some researchers believe that it was just such a stellar explosion that triggered the formation of the solar system from a cloud of dust and gas billions of years ago. Whether or not the Antarctic meteorites contain a record of that fateful cataclysm, they do contain a supernova by-product that has never before been found on Earth.

Researchers have identified so-called presolar grains in several primitive meteorites, which more or less preserve the chemistry of the raw materials from which they formed at the dawn of the solar system. Some presolar grains spilled into the molecular cloud that would become the solar system from nearby supernovae, and some seem to have arrived on the winds expelled from aging stars.

Presolar grains stand out from the rest because of their unusual mix of chemical isotopes, “which cannot be explained by any known process acting in the solar system,” according to a study in the May 1 issue of the Astrophysical Journal Letters. “Their isotopic compositions can only be explained by nuclear reactions occurring in stellar environments.”

In the new study (pdf), Pierre Haenecour of Washington University in St. Louis and his colleagues analyzed two meteorites collected in Antarctica in 2003, each named for a geographic feature near the spot where the meteorite fell. (Antarctica makes an ideal hunting ground for dark-colored meteorites, which stand out clearly against the ice fields.) Grove Mountains 021710, found by a Chinese expedition, and LaPaz Icefield 031117, collected by U.S. searchers, each harbor presolar grains of silica (SiO2), the researchers found, as evidenced by the grains’ enrichment in a heavy isotope of oxygen known as oxygen 18. That signature points to the grains’ formation in a type II supernova—the explosion initiated by the collapse of a massive star’s core. Other researchers had spotted presolar silica in meteorites before, but those grains had different isotopic signatures that indicated that they came from an aging star called an asymptotic giant branch (AGB) star rather than from a supernova.

The conclusion by Haenecour and his colleagues that a supernova seeded our corner of space with silica grains, among other types of dust, lends laboratory support to a 2008 study, using the Spitzer Space Telescope, that spotted the possible spectral signature of silica in the remnant of a supernova that exploded in the Milky Way so recently that its light reached Earth just 300 or so years ago.

Amassing and analyzing these presolar grains is more than just an exercise in interstellar history—a shock wave from a nearby supernova or the gentler expulsions of an AGB star could have stirred a cloud of dust and gas to collapse into the system of sun and planets that we inhabit today. Collecting presolar detritus allows astrophysicists a glimpse into the violent inner workings of dying stars and may ultimately help pinpoint just how the solar system came to be.

About the Author: John Matson is an associate editor at Scientific American focusing on space, physics and mathematics. Follow on Twitter @jmtsn.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. jpdickey 8:26 pm 04/24/2013

    See related article

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  2. 2. jtdwyer 3:10 am 04/25/2013

    Nice report, but there is one thing that I don’t understand:
    “… spotted the possible spectral signature of silica in the remnant of a supernova that exploded in the Milky Way so recently that its light reached Earth just 300 or so years ago.”
    When the light reached Earth has little bearing on when it was emitted, since it’s source could still be either 1 light year away or 100,000 light year’s away, correct?

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  3. 3. shorewood 2:47 pm 04/25/2013

    I don’t understand why this is a big deal. Didn’t everything in our solar system come from presolar supernovae?

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  4. 4. jh443 5:11 pm 04/25/2013

    If I remember correctly, it has been determined that every element heavier than iron requires the involvement of a supernova. If true, how is this any different than finding cobalt, nickel, copper and zinc?

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  5. 5. jh443 5:38 pm 04/25/2013

    jtdwyer: While it is true that an unknown star’s distance has little correlation to the date its light arrives on Earth, there is a formula that I consider interesting that can be applied.

    Assuming that the light from a star arrives 300 years before an object leaving from the same location:

    (x/ (300 + x)) * 100 = V


    x = distance of a star in light years, and
    V = Percent the speed of light required for an object to arrive from said star

    If the star was 100 light-years away, the object took 400 years to travel the same distance; therefore, the object travelled one quarter the speed of light.

    (100/400)*100 = 25%

    If the star was 300 light-years away:

    (300/600)*100 = 50%

    As the distance to the star increases, the required speed of the object approaches (but will not exceed) the speed of light.

    Assuming that the object’s average speed was 10% (or less) the speed of light:

    (x/(x+300))* 100 = 10

    100x = 10(x+300)
    100x = 10x+3000
    90x = 3000
    x = 33 1/3 light years (or less)

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  6. 6. peterbrm 4:05 am 04/27/2013

    The article said that the “possible silica spectra” was from the remnant of the supernova, so it is only the light from the remnant which has arrived here.
    “.. as little as 300 hundred years ago..” is a very round about way of referring to the youngest possible age of the supernova remnants at the time when the light showing signs of silica was emitted. It would have been helpful for the article to have stated this clearly, and the author should also have provided the oldest possible age of the remnants.

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