Can we say anything definitive about organic materials in the early Solar System? Perhaps so, judging from recent news from the Carnegie Institution. Researchers there have found organic particles from the days of Solar System formation inside meteorites. The material is similar to what is found in interplanetary dust particles believed to have come from comets, and gives us a view of the complexity of the organic mix that may have been available as the planets formed.
Studying six carbonaceous chondrite meteorites, the researchers looked at different isotopes of hydrogen and nitrogen associated with insoluble organic materials, which are extremely difficult to break down chemically. The relative proportion of these isotopes can reveal much about how the carbon was formed, and the meteorite samples show in some cases even higher amounts of the relevant isotopes than those found in interstellar dust.
“We have known for some time, for instance, that interplanetary dust particles (IDP), collected from high-flying airplanes in the upper atmosphere, contain huge excesses of these isotopes, probably indicating vestiges of organic material that formed in the interstellar medium,” says Larry Nittler, a co-author on the paper that was published in the May 5 issue of Science. “The IDPs have other characteristics indicating that they originated on bodies — perhaps comets — that have undergone less severe processing than the asteroids from which meteorites originate.”
But interplanetary dust particles provide only tiny samples; the new work makes it possible to examine much larger amounts of these materials from meteorites. What stands out to Centauri Dreams is a comment by another co-author, Conel Alexander: “…the parent bodies – the comets and asteroids — of these seemingly different types of extraterrestrial material are more similar in origin than previously believed.” And the study of early system organics just received a powerful boost.
Image (click to enlarge): These tiny particles, from carbonaceous chondrite meteorites, are just a few millionths of a meter wide and have different proportions of nitrogen (N) and hydrogen (H and D) isotopes. These isotopes are chemically bonded to meteoritic organic matter and can reveal a lot about what happened to the meteorite as it made its way through the solar system over billions of years. The two images show the regions with high levels of 15N and heavy hydrogen (deuterium or D)—indications that the associated carbon is very old and originated from interstellar matter or the outer regions of the solar system. Credit: Henner Busemann.
The paper is Busemann, Young, Alexander et al., “Interstellar Chemistry Recorded in Organic Matter from Primitive Meteorites,” Science (5 May 2006), pp. 727-730. Abstract available here.
Astrophysics, abstract
astro-ph/0702397
From: Alessandro Aronica [view email]
Date: Wed, 14 Feb 2007 22:58:35 GMT (204kb)
Combined Scanning Electron Microscope and Micro-InfraRed measurements on Interplanetary Dust Particles
Authors: A. Aronica (1), A. Rotundi (2), G. Ferrini (3), E. Palomba (4), E. Zona (2), L. Colangeli (1) ((1) INAF – Osservatorio Astronomico di Capodimonte, Napoli (Italy), (2) Dip. Scienze Applicate, Universita’ Parthenope, Napoli (Italy), (3) Novaetech s.r.l., Napoli (Italy), (4) INAF-IFSI, Roma (Italy))
Comments: 4 pages, 2 figures. Published in the Proceedings of the “I Workshop of Astronomy and Astrophysics for Students”, Eds. N.R. Napolitano & M. Paolillo, Naples, 19-20 April 2006 (astro-ph/0701577)
Laboratory characterization of Interplanetary Dust Particles (IDPs) collected in the lower stratosphere represents a concrete analysis of cosmic dust properties which played a fundamental role in the origin and evolution of Solar System. The IDPs were characterized by Field Emission Scanning Electron Microscope (FESEM) analyses and by InfraRed (IR) micro-spectroscopy.
We present the FESEM images of six IDPs: three smooth grains, two porous and one a compact sphere. We also show the results of micro-IR transmission measurements on four IDPs that allowed us to identify their spectral class according to the criteria defined by Sandford and Walker. Only three of the analyzed particles show IR transmission spectra with a dominant “silicate absorption feature” so that they could be assigned to the three IR spectral classes: one has been classified as “amorphous olivine”, one appears to be a mixture of “olivines” and “pyroxenes” and one belongs to the “layer-lattice silicates” spectral class.
http://arxiv.org/abs/astro-ph/0702397
Exploring Organic Environments in the Solar System
Task Group on Organic Environments in the Solar System, National Research Council
http://books.nap.edu/catalog.php?record_id=11860
Volatile Element Chemistry during Metamorphism of Ordinary Chondritic Material and Some of its Implications for the Composition of Asteroids
Authors: Laura Schaefer, Bruce Fegley Jr
(Submitted on 7 Jan 2008)
Abstract: We used chemical equilibrium calculations to model thermal metamorphism of ordinary chondritic material as a function of temperature, pressure, and trace element abundance and use our results to discuss volatile mobilization during thermal metamorphism of ordinary chondrite parent bodies. The calculations include ~1,700 solids and gases of 40 elements. We compiled trace element abundances in H-, L-, and LL-chondrites for the elements Ag, As, Au, Bi, Cd, Cs, Cu, Ga, Ge, In, Pb, Rb, Sb, Se, Sn, Te, Tl, and Zn, and identified abundance trends as a function of petrographic type within each class. We found that abundance patterns within the H- and L- chondrites are consistent with mobilization of volatile elements in an onionshell-type parent body. LL-chondrites have more complex abundance patterns that may support a rubble-pile model for the LL-chondrite parent body. We calculated volatility sequences for the trace elements in the ordinary chondritic material, which differs significantly from the solar nebula volatility sequence.
Comments: 64 pages, 14 figures, 5 tables; submitted to Icarus
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.1099v1 [astro-ph]
Submission history
From: Laura Schaefer [view email]
[v1] Mon, 7 Jan 2008 19:29:05 GMT (266kb)
http://arxiv.org/abs/0801.1099