Earliest stage of planet formation dated

December 19, 2007

UC Davis researchers have dated the earliest step in the formation of the solar system -- when microscopic interstellar dust coalesced into mountain-sized chunks of rock -- to 4,568 million years ago, within a range of about 2,080,000 years.

UC Davis postdoctoral researcher Frederic Moynier, Qing-zhu Yin, assistant professor of geology, and graduate student Benjamin Jacobsen established the dates by analyzing a particular type of meteorite, called a carbonaceous chondrite, which represents the oldest material left over from the formation of the solar system.

The physics and timing of this first stage of planet formation are not well understood, Yin said. So, putting time constraints on the process should help guide the physical models that could be used to explain it.

In the second stage, mountain-sized masses grew quickly into about 20 Mars-sized planets and, in the third and final stage, these small planets smashed into each other in a series of giant collisions that left the planets we know today. The dates of those stages are well established.

Carbonaceous chondrites are made up of globules of silica and grains of metals embedded in black, organic-rich matrix of interstellar dust. The matrix is relatively rich in the element manganese, and the globules are rich in chromium. Looking at a number of different meteorites collected on Earth, the researchers found a straight-line relationship between the ratio of the amount of manganese to that of chromium, the amount of matrix in the meteorites, and the amount of chromium-53.

These meteorites never became large enough to heat up from radioactive decay, so they have never been melted, Yin said. They are "cosmic sediments," he said.

By measuring the amount of chromium-53, Yin said, they could work out how much of the radioactive isotope manganese-53 had initially been present, giving an indication of age. They then compared the amount of manganese-53 to slightly younger igneous (molten) meteorites of known age, called angrites.

The UC Davis researchers estimate the timing of the formation of the carbonaceous chondrites at 4,568 million years ago, ranging from 910,000 years before that date to 1,170,000 years later.

"We've captured a moment in history when this material got packed together," Yin said.

The work is published in the Dec. 20 issue of Astrophysical Journal Letters, and was funded by grants from NASA.

Source: University of California - Davis

Explore further: It's elemental: Accurate analysis of Earth's core with molecular dynamics simulation

Related Stories

When tectonics killed everything

November 25, 2013

A new paper reveals how the worst extinction in Earth's history may have been tied to the formation of Supercontinent Pangea. The catastrophe wasn't triggered by an impact from above—unlike another well-known extinction—but ...

The Planet Saturn

August 3, 2015

The farthest planet from the Sun that be observed with the naked eye, the existence of Saturn has been known for thousands of years. And much like all celestial bodies that can be observed with the aid of instruments – ...

Recommended for you

Earth might have hairy dark matter

November 23, 2015

The solar system might be a lot hairier than we thought. A new study publishing this week in the Astrophysical Journal by Gary Prézeau of NASA's Jet Propulsion Laboratory, Pasadena, California, proposes the existence of ...

Scientists detect stellar streams around Magellanic Clouds

November 23, 2015

(Phys.org)—Astronomers from the University of Cambridge, U.K., have detected a number of narrow streams and diffuse debris clouds around two nearby irregular dwarf galaxies called the Magellanic Clouds. The research also ...

The hottest white dwarf in the Galaxy

November 25, 2015

Astronomers at the Universities of Tübingen and Potsdam have identified the hottest white dwarf ever discovered in our Galaxy. With a temperature of 250,000 degrees Celsius, this dying star at the outskirts of the Milky ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Dec 20, 2007
Interstellar dust is hydrogen/helium. So explain the manganese/chromium formation.
not rated yet Dec 22, 2007
Interstellar gas is hydrogen and helium. Interstellar dust contains a variety of substances that are the remains of exploded stars.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.