Researchers find new information about Earth's origins

Oct 05, 2006
Mukul Sharma and Rasmus Andreasen (Joseph Mehling '69)
Mukul Sharma and Rasmus Andreasen (Joseph Mehling '69)

Two Dartmouth researchers have learned more about the origins and makeup of the solar nebula, the large gaseous cloud thought to have spawned the solar system. Mukul Sharma, assistant professor of Earth sciences, and graduate student Rasmus Andreasen, have found evidence that more than one dying star, or supernova, contributed to the makeup of the solar nebula, which in turn, provides insights into the evolution of planets and asteroids soon after their birth some 4,500 million years ago.

Their study appears in Science Express, the advance online publication of the journal Science, on October 5, 2006.

"Supernovae are dying stars that burst with tremendous energy creating new isotopes and throwing a huge amount of material into interstellar space," says Sharma. "There are two mechanisms that forge isotopes in a supernova-some are produced by high temperature disintegration of previously existing isotopes and others by neutron-induced transmutations.

It has been commonly thought that a single type of supernova supplied isotopes to the primordial soup that was the hot and spinning solar nebula. By investigating the samarium and neodymium isotopic composition of primitive meteorites, which are building blocks of planets, we find that those isotopes that were produced by high temperature disintegration did not mix well in the solar nebula while those generated by neutron-induced transmutations did."

This finding led the researchers to conclude that there was more than one type of supernova matter. A possible reason for a sluggish mixing in the solar nebula is the increase in the grain size from the sun outwards, which then would affect how isotopes were absorbed on the surfaces of grains.

This research also has a bearing on using the samarium and neodymium isotopes in meteorites as way to understand the evolution of Earth and other planets. The researchers found that carbonaceous stony meteorites that come from the distant edge of the asteroid belt possess a distinct blend of samarium and neodymium isotopes in comparison with the stony meteorites with little carbon, an asteroid called 4 Vesta, and the Moon.

"This suggests that the isotopic composition of the Earth prior to any evolutionary modifications should be akin to these carbon-poor meteorites," says Sharma. "However there is a small but resolvable gap between the neodymium isotopic composition of the Earth's upper mantle and the presumed composition of the entire Earth. This indicates that there was formation of continents on Earth within a few million years after its birth. The neodymium isotopes are telling us that these continents are buried somewhere on Earth and hidden from direct observation."

Source: Dartmouth College

Explore further: Experts express concern over cyclone trends in the British-Irish Isles

Related Stories

A brief history of nukes in space

Jun 26, 2015

In just a few short weeks, NASA's New Horizons spacecraft will make its historic flyby of Pluto and its moons. Solar panels are unable to operate in the dim nether regions of the outer solar system, and instead, ...

Rosetta and Philae at comet 67P/Churyumov-Gerasimenko

Jun 22, 2015

Rosetta has been exploring comet 67P/Churyumov-Gerasimenko since summer 2014. In November 2014, the Philae lander landed on the surface of the comet. The first measurements by the scientific instruments allow ...

The difference between asteroids and meteorites

Jun 03, 2015

Asteroids, meteors, and meteorites … It might be fair to say these rocks from space inspire both wonder and fear among us Earthlings. But knowing a bit more about each of them and how they differ may eliminate ...

UW researchers scaling up fusion hopes

Jun 02, 2015

Producing reliable fusion energy—the same process that powers the sun—has long been a holy grail of scientists here on Earth. It releases no greenhouse gases, can be fueled by elements found in seawater ...

Recommended for you

NASA sees Typhoon Nangka strengthen

1 hour ago

NASA's Aqua satellite passed over Typhoon Nangka on July 6 and took an infrared look at the large storm as it strengthened from a tropical storm into a typhoon.

User comments : 0

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.