December 2, 2020

They find the oldest material on Earth, prior to the formation of the Sun

As if a time capsule were treated, the Murchison meteorite, which fell 50 years ago in Australia, had this presolar powder integrated

The official scientific journal of the National Academy of Sciences of the United States, known by its acronym PNAS, has released what is the oldest material on Earth. It is stellar dust that formed between 5,000 and 7,000 million years ago, even before the Sun formed 4.6 billion years ago. This matter has been found in a meteorite that fell in Australia fifty years ago. The study, entitled “Life span of interstellar dust by exposure to cosmic rays ages of presolar silicon carbide,” has explained that “presolar grains are the oldest datable solid samples available and that provide an invaluable insight into the preschool chronology of our galaxy. “

Having found this material with such antiquity is a historical achievement since presolar grains are difficult to find. It is estimated that they are only present in 5% of meteorites that fall to Earth. Once found, the method, in order to age the oldest material in the known system, has been to determine the age through the study of the neon (Ne) isotopes produced by the galactic cosmic rays. This age distribution It has also confirmed the hypothesis that these grains originate from stars that initially formed 7,000 million years ago and that produced dust 5,000 million years ago. That there are grains with such ages supposes, among other things, that this stellar dust managed to evade destruction in supernova shock waves.

The Murchison meteorite, where this matter has been found and whose fragments fell on the Murchison town, Victoria, in Australia on September 28, 1969, has acted as a kind of time capsule, and the presolar grains analyzed in the study had remained integrated and unchanged in it. These grains were isolated for analysis by creating a kind of paste that, by dissolving in acid, dissolved, leaving only the solar grains. Through this method the scientists managed to separate the star dust from the meteorite and know their age and the type of star to which they belonged. This research has revealed, in addition to the oldest material on Earth, that there are stellar powders between 4,600 and 4,900 million years that were formed in a period of improved star formation in which more stars were formed than usual.

Thus, thanks to the stellar dust found, it has been revealed that 7,000 million years ago, almost 3,000 million years before the formation of the Sun, stars were formed that subsequently expelled material, thanks to which today we can talk about the oldest stellar dust, known moment, of our system. As stated by the research team that conducted the study, this It can provide unique information about the interstellar dust cycle and star formation events in the Galaxy before the birth of the Sun.


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