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

May 2017
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
April 30, 2017 May 1, 2017 May 2, 2017 May 3, 2017 May 4, 2017 May 5, 2017 May 6, 2017
May 7, 2017 May 8, 2017 May 9, 2017 May 10, 2017 May 11, 2017 May 12, 2017 May 13, 2017
May 14, 2017 May 15, 2017 May 16, 2017 May 17, 2017 May 18, 2017 May 19, 2017 May 20, 2017
May 21, 2017 May 22, 2017 May 23, 2017 May 24, 2017 May 25, 2017

Phoenix Comicon

Phoenix Comicon
May 26, 2017

Phoenix Comicon

Phoenix Comicon
May 27, 2017

Phoenix Comicon

Phoenix Comicon
May 28, 2017

Phoenix Comicon

Phoenix Comicon
May 29, 2017 May 30, 2017 May 31, 2017 June 1, 2017 June 2, 2017 June 3, 2017

Frequently Asked Questions

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


Meteorite of the Month

Katol

May’s meteorite of the month is Katol, an (L6) ordinary chondrite that fell over the town of Katol, in the Nagpur District of India, the afternoon of May 22, 2012. …


Graduate Student Spotlight: Emilie Dunham

Emilie Dunham received her B.S. in Astronomy (with minors in Geology and Physics) from Case Western Reserve University in 2014.  As an undergraduate student, Emilie worked with Dr. Ralph Harvey …


CMS News

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