UH scientists analyze a tiny comet grain to date Jupiter's formation

March 1, 2012
Comet 81P/Wild 2 was brought to Earth in 2006 by NASA's Stardust spacecraft. Credit: NASA/JPL/Caltech

Particles from comet 81P/Wild 2 brought to Earth in 2006 by NASA's Stardust spacecraft indicate that Jupiter formed more than three million years after the formation of the first solids in our Solar System. The new finding helps test Solar System formation theories, which do not agree on the timing of Jupiter though it is certain the formation of this giant planet affected how materials moved, collided, and coalesced during the complex planet-forming process.

Published in the February 1, 2012 issue of the are new results from laboratory analyses on a tiny fragment in one of the particles. Dr. Ryan Ogliore, a postdoctoral researcher at the Hawaii Institute of Geophysics and Planetology (HIGP, University of Hawaii) conducted the research with Drs. Gary Huss and Kazuhide Nagashima, also from HIGP, and colleagues from the University of California at Berkeley, University of Washington, and the Lawrence Berkeley National Laboratory.

Comets formed in the frigid out beyond Neptune, but analyses of the Wild 2 samples showed that comets are composed of low-temperature and high-temperature materials that must have come from completely different environments. The team led by Ogliore analyzed a chondrule fragment known from previous research to have formed by high-temperature processes in the inner solar nebula—the cloud of gas and dust surrounding the infant Sun from which the planets formed. What could be more contradictory than high-temperature objects from the innermost regions near the Sun becoming the predominant dust components of an icy comet in the outer solar nebula? Ogliore and colleagues set out to determine when this grand, outward migration of materials occurred.

Using the University of Hawaii Cameca ims 1280 ion microprobe, the team measured magnesium isotopes (26Mg is the decay product of the short-lived radioactive isotope 26Al) and elemental aluminum (27Al) in their sample to bracket its formation age. Aluminum-26, with a half-life of 730,000 years, is the extremely useful clock that cosmochemists use to date ancient events since the 26Al/27Al ratio varies in objects that formed at different times. Ogliore and team found no evidence for extinct 26Al, meaning the cometary fragment formed after nearly all the 26Al had decayed. Assuming homogenous distribution of 26Al in at least the inner solar nebula, their results suggest the fragment formed at least three million years after the first solids formed. And this would have happened before Jupiter could have interfered, for theory says that a growing Jupiter would have accreted material so efficiently as to open a gap in the . This gap would have posed a barrier to the outward migration of any material formed nearer the Sun than Jupiter's orbit, such as the fragment analyzed by Ogliore and team. The timing implies Jupiter formed more than three million years after the formation of the first solids in our Solar System. "We were surprised to find such a late-forming, high-temperature little rock in these cometary samples," said Dr. Ogliore. "That we are able to test theories about the formation time of Jupiter and consequently, the origins of our is really a testament to the importance of sample-return missions like Stardust."

Explore further: First measurement of the age of cometary material

More information: Ogliore, R. C., Huss, G. R., Nagashima, K., Butterworth, A. L., Gainsforth, Z., Stodolna, J., Westphal, A. J., Jowsiak, D., and Tyliszczak, T. (2012) Incorporation of a Late-forming Chondrule into Comet Wild 2, Astrophysical Journal Letters, v. 745:L19-L23, doi:10.1088/2041-8205/745/2/L19

Related Stories

First measurement of the age of cometary material

February 25, 2010

(PhysOrg.com) -- Though comets are thought to be some of the oldest, most primitive bodies in the solar system, new research on comet Wild 2 indicates that inner solar system material was transported to the comet-forming ...

Stardust Findings May Alter View of Comet Formation

March 14, 2006

Samples from comet Wild 2 have surprised scientists, indicating the formation of at least some comets may have included materials ejected by the early sun to the far reaches of the solar system.

Synchrotrons Help Reveal the Nature of Comets

December 19, 2006

Cometary particles returned to Earth by the Stardust spacecraft are yielding precious information about the origin of the solar system, thanks in part to a collaboration that includes the Stanford Synchrotron Radiation Laboratory ...

'Ultra-primitive' particles found in comet dust

November 2, 2009

Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from the Carnegie Institution. The stratospheric dust includes ...

The origin of comet material formed at high temperatures

July 22, 2011

Comets are icy bodies, yet they are made of materials formed at very high temperatures. Where do these materials come from? French researchers have now provided the physical explanation behind this phenomenon. They have demonstrated ...

Recommended for you

Bursts of methane may have warmed early Mars

January 24, 2017

The presence of water on ancient Mars is a paradox. There's plenty of geographical evidence that rivers periodically flowed across the planet's surface. Yet in the time period when these waters are supposed to have run—three ...

Gaia turns its eyes to asteroid hunting

January 24, 2017

While best known for its surveys of the stars and mapping the Milky Way in three dimensions, ESA's Gaia has many more strings to its bow. Among them, its contribution to our understanding of the asteroids that litter the ...

Dwarf galaxies shed light on dark matter

January 23, 2017

The first sighting of clustered dwarf galaxies bolsters a leading theory about how big galaxies such as our Milky Way are formed, and how dark matter binds them, researchers said Monday.

One of the brightest distant galaxies known discovered

January 23, 2017

An international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna (ULL) has discovered one of the brightest "non-active" galaxies in the early universe. Finding ...


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.