London, May 7 (ANI): Cosmic 'dandruff'- fluffy specks of carbon-rich dust found in Antarctic snow seem to be relics from the dawn of the solar system, when the planets were still forming- could help explain how the carbon needed for life wound up on Earth.
Researchers led by Jean Duprat of the University of Paris-South in Orsay, France, melted Antarctic snow and filtered particles from the resulting water, turning up two extraterrestrial dust particles, reports New Scientist.
The particles are relatively large, at 80 and 275 micrometres across.
The researchers carried out a lot of deuterium, a heavy isotope of hydrogen- they have 10 to 30 times as much as typical terrestrial materials.
At cold temperatures, deuterium atoms are incorporated into solid materials more readily than hydrogen atoms are, which suggests that the particles formed in the frigid outer reaches of the cloud of gas and dust that gave rise to our solar system.
The fluff-balls are also extremely rich in carbon.
In one of the dust grains, carbonaceous material accounts for 48 per cent of the area analysed so far, while it makes up 85 per cent of the area studied in the other dust grain - an amount as high as any particle of interplanetary dust studied before.
It is known that carbon is a crucial element for the development of life, and Earth's supply of it must have had an extraterrestrial source.
This is because temperatures at Earth's orbital distance from the sun were too warm for solid carbon to condense out of the solar system's natal cloud.
Some of the carbon may have rained down from space in particles like those found in Antarctica, said Donald Brownlee of the University of Washington in Seattle, who was not involved in the study.
The particles were likely sloughed off by comets that wandered into the inner solar system.
Comets probably delivered a "significant fraction" of Earth's carbon, said Brownlee.
Fragments of the fluffy particles may have come from asteroids, too.
That could explain micrometre-sized grains rich in deuterium that had previously been found in some meteorites, said the researchers.
The particles also provide new evidence that material in the inner and outer regions of the solar system's birth cloud mixed together early on.
That's because some minerals inside the particles had to be forged at high temperatures.
They probably formed near the sun before migrating outwards to be incorporated into the dust grains, SAID the team.
High-temperature minerals were previously found in comet material collected by NASA's Stardust mission.
The study was published in Science. (ANI)