Center for Meteorite Studies

The ASU Center for Meteorite Studies is pleased to announce that François Tissot, a graduate student at the University of Chicago, is the recipient of the 2015 Nininger Meteorite Award.

Francois TissotFrançois’s paper “Origin of uranium isotope variations in early solar nebula condensates” describes how the characterization of the U isotope composition of 12 fine-grained Calcium and Aluminum-rich Inclusions (CAIs: The earliest solids to form in the Solar System) demonstrates that the decay of Curium-247 is the main process responsible for the variability of the 238U/235U ratios of CAIs.

The discovery in the late 2000s that the 238U/235U ratios of meteoritic materials varied by up to several permil, meant that previously published Pb-Pb ages of CAIs (and thus of the Solar System) were unreliable. The cause of this variability has been heavily debated; some argued that it was due to 247Cm decay, while others preferred scenarios that invoked fractionation upon condensation. Despite numerous attempts since the late 1970s, until now, no study has been able to unambiguously show that 247Cm was alive in the early Solar System and could be responsible for the variable U isotope composition in CAIs.

By studying fine-grained CAIs depleted in U and potentially enriched in Cm, François and his co-workers were able to resolve excesses of 235U due to 247Cm decay reaching ~+6% relative to average Solar System composition. Combined with modeling of the chemical evolution of the galaxy, the early Solar System abundance of 247Cm points to a universality of the r-process of nucleosynthesis, provided that Hafnium-182 has an s-process origin. Multiple r-process sites have been considered in the past but may only be relevant to exotic conditions prevailing in the earliest generation of stars of the Galaxy.


Category: CMS News

Comments are closed.

Sign Up for Center Updates!

Be the first to learn about CMS events and news; sign up for email updates here!


Facebook
Twitter
YouTube


Upcoming Events

September 2016
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
August 28, 2016 August 29, 2016 August 30, 2016 August 31, 2016 September 1, 2016 September 2, 2016 September 3, 2016
September 4, 2016 September 5, 2016 September 6, 2016 September 7, 2016 September 8, 2016 September 9, 2016 September 10, 2016
September 11, 2016 September 12, 2016 September 13, 2016 September 14, 2016 September 15, 2016 September 16, 2016 September 17, 2016
September 18, 2016 September 19, 2016 September 20, 2016 September 21, 2016 September 22, 2016 September 23, 2016

Earth & Space Open House

September 24, 2016
September 25, 2016 September 26, 2016 September 27, 2016 September 28, 2016 September 29, 2016 September 30, 2016 October 1, 2016

Frequently Asked Questions

Click here to find the answers to the most common questions asked of the Center for Meteorite Studies!


Graduate Student Spotlight - Prajkta Mane

Prajkta Mane received her B.Sc. in Geology from the University of Mumbai (St. Xavier’s College) in 2008, followed by her M.Sc. in Applied Geology from the Indian Institute of Technology …


Meteorite of the Month

Carancas

September's meteorite of the month is Carancas, an (H4-5) ordinary chondrite that fell in Peru, the afternoon of September 15, 2007. To date, over 340g of material have been recovered. …


CMS News

Catch up on all the latest news from the Center for Meteorite Studies!