. 24/7 Space News .
EXO WORLDS
Evidence found for unstable heavy element at solar system formation
by Staff Writers
Chicago IL (SPX) Mar 07, 2016


This close-up picture shows a ceramic-like refractory inclusion (pink inclusion) still embedded into the meteorite in which it was found. Refractory inclusions are the oldest-known rocks in the solar system (4.5 billion years old). Analysis of the uranium isotope ratios of such inclusions demonstrates that a long-lived isotope of the radioactive element curium was present in the solar system when this inclusion was formed. The inclusion measures 1.5 centimers (.59 inches) in length. Image courtesy Origins Lab, University of Chicago. For a larger version of this image please go here.

University of Chicago scientists have discovered evidence in a meteorite that a rare element, curium, was present during the formation of the solar system. This finding ends a 35-year-old debate on the possible presence of curium in the early solar system, and plays a crucial role in reassessing models of stellar evolution and synthesis of elements in stars. Details of the discovery appear in the March 4 edition of Science Advances.

"Curium is an elusive element. It is one of the heaviest-known elements, yet it does not occur naturally because all of its isotopes are radioactive and decay rapidly on a geological time scale," said the study's lead author, Francois Tissot, UChicago PhD'15, now a W.O. Crosby Postdoctoral Fellow at the Massachusetts Institute of Technology.

And yet Tissot and his co-authors, UChicago's Nicolas Dauphas and Lawrence Grossman, have found evidence of curium in an unusual ceramic inclusion they called "Curious Marie," taken from a carbonaceous meteorite. Curium became incorporated into the inclusion when it condensed from the gaseous cloud that formed the sun early in the history of the solar system.

Curious Marie and curium are both named after Marie Curie, whose pioneering work laid the foundation of the theory of radioactivity. Curium was only discovered in 1944, by Glenn Seaborg and his collaborators at the University of California, Berkeley, who, by bombarding atoms of plutonium with alpha particles (atoms of helium) synthesized a new, very radioactive element.

To chemically, and unambiguously, identify this new element, Seaborg and his collaborators studied the energy of the particles emitted during its decay at the Metallurgical Laboratory at UChicago (which later became Argonne National Laboratory). The isotope they had synthesized was the very unstable curium-242, which decays in a half-life of 162 days.

On Earth today, curium exists only when manufactured in laboratories or as a byproduct of nuclear explosions. Curium could have been present, however, early in the history of the solar system, as a product of massive star explosions that happened before the solar system was born.

"The possible presence of curium in the early solar system has long been exciting to cosmochemists, because they can often use radioactive elements as chronometers to date the relative ages of meteorites and planets," said study co-author Nicolas Dauphas, UChicago's Louis Block Professor in Geophysical Sciences.

Indeed, the longest-lived isotope of curium (247Cm) decays over time into an isotope of uranium (235U). Therefore, a mineral or a rock formed early in the solar system, when 247Cm existed, would have incorporated more 247Cm than a similar mineral or rock that formed later, after 247Cm had decayed. If scientists were to analyze these two hypothetical minerals today, they would find that the older mineral contains more 235U (the decay product of 247Cm) than the younger mineral.

"The idea is simple enough, yet, for nearly 35 years, scientists have argued about the presence of 247Cm in the early solar system," Tissot said.

Early studies in the 1980s found large excesses of 235U in any meteoritic inclusions they analyzed, and concluded that curium was very abundant when the solar system formed. More refined experiments conducted by James Chen and UChicago alumnus Gerald Wasserburg, SB'51, SM'52, PhD'54, at the California Institute of Technology showed that these early results were spurious, and that if curium was present in the early solar system, its abundance was so low that state-of-the-art instrumentation would be unable to detect it.

Scientists had to wait until a new, higher-performance mass spectrometer was developed to successfully identify, in 2010, tiny excesses of 235U that could be the smoking gun for the presence of 247Cm in the early solar system.

"That was an important step forward but the problem is, those excesses were so small that other processes could have produced them," Tissot noted.

Models predict that curium, if present, was in low abundance in the early solar system. Therefore, the excess 235U produced by the decay of 247Cm cannot be seen in minerals or inclusions that contain large or even average amounts of natural uranium. One of the challenges was thus to find a mineral or inclusion likely to have incorporated a lot of curium but containing little uranium.

With the help of study co-author Lawrence Grossman, UChicago professor emeritus in geophysical sciences, the team was able to identify and target a specific kind of meteoritic inclusion rich in calcium and aluminum. These CAIs (calcium, aluminum-rich inclusions) are known to have a low abundance of uranium and likely to have high curium abundance. One of these inclusions - Curious Marie - contained an extremely low amount of uranium,

"It is in this very sample that we were able to resolve an unprecedented excess of 235U," Tissot said. "All natural samples have a similar isotopic composition of uranium, but the uranium in Curious Marie has six percent more 235U, a finding that can only be explained by live 247Cm in the early solar system."

Thanks to this sample, the research team was able to calculate the amount of curium present in the early solar system and to compare it to the amount of other heavy radioactive elements such as iodine-129 and plutonium-244. They found that all these isotopes could have been produced together by a single process in stars.

"This is particularly important because it indicates that as successive generations of stars die and eject the elements they produced into the galaxy, the heaviest elements are produced together, while previous work had suggested that this was not the case," Dauphas explained.

The finding of naturally occurring curium in meteorites by Tissot and collaborators closes the loop opened 70 years ago by the discovery of man-made Curium and it provides a new constraint, which modelers can now incorporate into complex models of stellar nucleosynthesis and galactic chemical evolution to further understand how elements like gold were made in stars.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
University of Chicago
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
EXO WORLDS
Imaging Technique May Help Discover Earth-Like Planets Around Other Stars
Melbourne FL (SPX) Feb 26, 2016
One of the biggest quests in astrophysics is to find Earth-like planets around other stars - places where life may exist. Regular telescopes are not good at directly imaging such small objects because a host star's light generally drowns out the relatively dimmer light of a potential planet. But a new development in space imaging may solve that vexing problem. A study led by Florida Instit ... read more


EXO WORLDS
China to use data relay satellite to explore dark side of moon

NASA May Return to Moon, But Only After Cutting Off ISS

Lunar love: When science meets artistry

New Lunar Exhibit Features NASA's Lunar Reconnaissance Orbiter Imagery

EXO WORLDS
Great tilt gave Mars a new face

SSL developing robotic sample handling assembly for Mars 2020

Monster volcano gave Mars extreme makeover: study

Space simulation crew hits halfway mark til August re-entry

EXO WORLDS
Launch America: Suni Williams on Commercial Crew

Sore, but no taller, astronaut Scott Kelly adjusts to Earth

Test Dummies to Help Assess Crew Safety in Orion

Orion launch abort motor case passes structural qualification test

EXO WORLDS
China to Launch Over 100 Long March Rockets Within Five Years

China's lunar probe sets record for longest stay

Moving in to Tiangong 2

Logistics Rule on Tiangong 2

EXO WORLDS
International Space Station's '1-year crew' returns to Earth

Scott Kelly and Mikhail Kornienko return to Earth after One-Year Mission

Paragon wins NASA ISS water processor development contract

NASA's Science Command Post Supports Scott Kelly's Year In Space

EXO WORLDS
SpaceX launches SES-9 satellite to GEO; but booster landing fails

US Space Company in Talks With India to Launch Satellite

At last second, SpaceX delays satellite launch again

Arianespace Soyuz to launch 2 Galileo satellites in May

EXO WORLDS
Imaging Technique May Help Discover Earth-Like Planets Around Other Stars

Newly discovered planet in the Hyades cluster could shed light on planetary evolution

Imaging technique may help discover Earth-like planets

Longest-Lasting Stellar Eclipse Discovered

EXO WORLDS
Spacepath Communications creates new joint venture with Polarity in US

University of Kentucky physicist discovers new 2-D material that could upstage graphene

UMass Amherst team offers new, simpler law of complex wrinkle patterns

Disney automated system lets characters leap and bound realistically in virtual worlds









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.