Fifty years ago a meteorite fell on Australia and scientists have now discovered in the Star dust formed about 7,000 million years ago, which makes it the oldest solid material found so far on Earth.
That material "tells us about how the stars formed in our galaxy," said the curator of the American Field Museum and associate professor at the Chicao Philipp Heck University, principal signatory of the study published by PNAS and which he described as "one of the most exciting "in which he has worked.
The remains that are between 5,000 and 7,000 million years old are called presolar mineral grains, since they were formed before the birth of our star, which is about 4.6 billion years old.
"They are solid samples of stars, real stardust," which got caught in meteorites and that has remained unchanged for billions of years, making them authentic time capsules from a time before the Solar System, explains a statement from the Field Museum.
These types of presolar grains are very rare, since they are found in only five percent of the meteorites fallen on Earth and also their size in tiny.
In 1969 a meteorite fell in the Australian town of Murchison and from which the Field Museum retains most of it for study, which were isolated presolar grains in a laborious process.
To guess what kind of stars the grains came from and how old they used a technique that measure exposure to cosmic rays, which interact with matter and form new elements. "The longer they are exposed the more elements are created.
Some of the presolar grains were the oldest discovered, up to 5.5 billion years ago, but since these are formed when the stars die "they can tell us their story" and 7,000 million ago it is estimated that there was a kind of astral "baby boom" , during which many of these stars were formed.
This discovery, the statement said, provides data to deepen the scientific debate about whether new stars form at a constant rate or if ups and downs occur over time.
"Some people think that the galaxy's star formation rate is constant," says Heck, but thanks to these grains, "we now have direct evidence of a period of increased star formation in our galaxy 7,000 million years ago with samples of meteorites. This is one of the key findings of our study. "