Ancient stone may have originated from rare supernova, scientists say

An "extraterrestrial" stone found in the Egyptian desert almost three decades ago could be the first piece of evidence found on Earth of a rare supernova explosion, a group of researchers has proposed.

A study published recently in the journal Icarus by researchers, including some from the University of Johannesburg in South Africa, analyzed the chemistry of the Hypatia stone, first found in southwest Egypt in 1996 and named after the prominent woman astronomer and mathematician Hypatia of Alexandria.

The researchers say previous studies have determined the stone did not form on Earth and had to be extraterrestrial. It also is not from any known type of meteorite or comet.

They suggest, instead, that the stone's origins come from a red giant star, at the end of its life, which collapsed into a dense white dwarf star inside of a gigantic dust cloud known as a nebula.

The white dwarf star eventually "ate" the other star, they say, becoming unstable and exploding inside the dust cloud as a supernova type Ia, described as one of the most energetic events in the universe.

Type Ia supernovas happen once or twice per galaxy per century, the researchers say, but make most of the iron found in the universe. They say most of the steel on Earth was once the element iron created by Ia supernovas.

"If this hypothesis is correct, the Hypatia stone would be the first tangible evidence on Earth of a supernova type Ia explosion," researcher Jan Kramers said in a news release from the University of Johannesburg.

Millions of years later, the researchers say the "bubble" slowly solidified into a rock or "cosmic dust bunny," likely in a cold and uneventful outer part of the solar system such as the Oort cloud, the most distant part of our solar system, or in the region of icy bodies beyond Neptune's orbit known as the Kuiper belt.

At some point, this rock hurtled toward Earth, shattering and creating micro-diamonds as it entered Earth's atmosphere and made impact in the Great Sand Sea in southwestern Egypt.

Researchers believe the Hypatia stone is one of many fragments of the original rock.

"Perhaps equally important, it shows that an individual anomalous 'parcel' of dust from outer space could actually be incorporated in the solar nebula that our solar system was formed from, without being fully mixed in," Kramers said.

"This goes against the conventional view that dust which our solar system was formed from, was thoroughly mixed."