Formation of the earliest solids: Clues from 26Al
Lead Research Organisation:
Natural History Museum
Department Name: Earth Sciences
Abstract
We know that the solar system formed about four and a half billion years ago when a cloud of dust and gas collapsed to form the Sun and planets. As the Sun formed, a swirling dusty disk evolved around it, called the accretion disk. Left over material from this disk eventually became the planets. We can learn about the solar system when it was at this stage by studying some meteorites that date from this era, the chondrites. If you look at chondritic meteorites you can see that they contain little round balls with a diameter of about 0.1 to 1 mm, called chondrules. These formed in the accretion disk around the nascent sun. Chondrule formation is an important step in the hierarchy of grain growth from interstellar, nanometer sized grains that made up the accretion disk to planets, which are thousands of kilometres in diameter. Chondrules obtained their round shape when they were molten for only a few minutes at very high temperatures of up to >2000 degree C. Although the formation of an individual chondrule was brief, there is some first evidence that the process causing this 'flash' heating was active for 1-2 Million years. One aim of this study is to constrain the time interval during which chondrule formation was an active process in the accretion disk. There is also some indication that chondrules with a different chemical compositions formed at different times. This would be an exciting finding, as it would document a chemical evolution of the accretion disk with time, recorded in chondrules. This would help us understand how the accretion disk changed with time as the planet forming process progressed. However, the data available so far are still ambiguous. A focus of the study is therefore to determine both the chemical composition and the age of a single chondrule and verify whether there is a correlation between them. We can learn about all this using a radioactive isotope, 26Al. Aluminium-26 was present in the early solar system, but since it is radioactive with a very short half-life it decayed away and so the quantity lessened to essentially zero about 10 Million years after the beginning of the solar system. However, if a mineral formed early within this 10 Million years and incorporated 26Al, its decay product 26Mg can be measured today and we can re-calculate how much 26Al was initially in the chondrule. This may then give us an idea of its age. There is a complication in that some chondrules may contain fragments of older materials and addition of this may affect the 26Al data. We will look for this by studying the chondrule visually and making chemical measurements on it.
People |
ORCID iD |
Sara Russell (Principal Investigator) | |
Dominik Hezel (Researcher) |
Publications
BULLOCK E
(2010)
Sulfur isotopic composition of Fe-Ni sulfide grains in CI and CM carbonaceous chondrites
in Meteoritics & Planetary Science
Elangovan P
(2012)
PhaseQuant: A tool for quantifying tomographic data sets of geological specimens
in Computers & Geosciences
Giscard M. D.
(2012)
TRACE ELEMENT COMPOSITION OF METAL AND SULPHIDES IN IRON METEORITES DETERMINED USING ICP-MS
in METEORITICS & PLANETARY SCIENCE
Griffin L
(2012)
Improved segmentation of meteorite micro-CT images using local histograms
in Computers & Geosciences
Hallis L
(2010)
The oxygen isotope composition, petrology and geochemistry of mare basalts: Evidence for large-scale compositional variation in the lunar mantle
in Geochimica et Cosmochimica Acta
Hallis L. J.
(2009)
OXYGEN ISOTOPIC COMPOSITION OF MARE-BASALTS: MAGMA OCEAN DIFFERENTIATION AND SOURCE HETEROGENEITY
in METEORITICS & PLANETARY SCIENCE
Hezel D
(2010)
A nebula setting as the origin for bulk chondrule Fe isotope variations in CV chondrites
in Earth and Planetary Science Letters
Hezel D
(2013)
Visualisation and quantification of CV chondrite petrography using micro-tomography
in Geochimica et Cosmochimica Acta
HEZEL D
(2010)
Quantifying the error of 2D bulk chondrule analyses using a computer model to simulate chondrules (SIMCHON) Quantifying the error of 2D bulk chondrule analyses
in Meteoritics & Planetary Science
Hezel D
(2010)
The chemical relationship between chondrules and matrix and the chondrule matrix complementarity
in Earth and Planetary Science Letters
Description | We found that early solar system formed objects, chondrules, can have variable amounts of 26Al when they formed. This may have been because they formed at different times or from different starting materials. This is important as it affects how hot the planets would have become due to radioactive heating. |
Exploitation Route | We are now trying to make the measurements at higher precision and are combining these high precision measurements with in situ measurements. |
Sectors | Aerospace, Defence and Marine,Education,Culture, Heritage, Museums and Collections |
URL | http://www.nhm.ac.uk/research-curation/earth-sciences/mineral-planetary-sciences/extraterrestrial-materials/index.html |
Description | This work lead directly into the following grant, ST/J001473/1. We have been investigating the distribution of 26Al in the early solar system and how this can be used as a tracer of early solar system mixing and as a chronometer. This work has been very effective as a springboard for public engagement activities. |
First Year Of Impact | 2009 |
Sector | Aerospace, Defence and Marine,Education,Culture, Heritage, Museums and Collections |
Impact Types | Cultural,Societal |
Description | Collaboration with the university of Koln |
Organisation | University of Cologne |
Country | Germany |
Sector | Academic/University |
PI Contribution | This is a new collaboration that has been set us as an outcome from the grant. The PDRA Dr Hezel funded by the grant moved to Germany and we continue to colloborate on planetary science projects. |
Collaborator Contribution | Our partner Dr Hezel has been modelling data that we acquire in our experiments. |
Impact | We have just had a paper accepted in the journal Meteoritics and Planetary sciences. |
Start Year | 2012 |
Description | School Visits |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Type Of Presentation | Keynote/Invited Speaker |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | The funded PDRA and PI visited around 6 schools per year in the regional areas to give talks. These were to all ages, from Key Stage 1 to 4. Feedback from schools was always good. The pupils enjoyed meeting "real scientists" and it gave them an idea of what a scientific career might involve. |
Year(s) Of Engagement Activity | 2007,2008,2009 |