¹Maksimova, A.A., ^1,2Oshtrakh, M.I., ³Klencsár, Z., ¹Petrova, E.V., ¹Grokhovsky, V.I., ⁴Kuzmann, E., ⁴Homonnay, Z., ^1,2Semionkin, V.A.

¹ Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002, Russian Federation
² Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002, Russian Federation
³ Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest 1117, Hungary
⁴ Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary

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Reference
Maksimova AA, Oshtrakh MI, Klencsár Z, Petrova EV, Grokhovsky VI, Kuzmann E, Homonnay Z, Semionkin VA (2014) A comparative study of troilite in bulk ordinary chondrites Farmington L5, Tsarev L5 and Chelyabinsk LL5 using Mössbauer spectroscopy with a high velocity Resolution. Journal of Molecular Structure (in Press).

Link to Article [DOI: 10.1016/j.molstruc.2014.05.049]

¹M. Jura, ¹B. Klein, ¹S. Xu (许偲艺), ²E. D. Young
¹ Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1562, USA
² Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA

Relative to calcium, both strontium and barium are markedly enriched in Earth’s continental crust compared to the basaltic crusts of other differentiated rocky bodies within the solar system. Here, we both re-examine available archived Keck spectra to place upper bounds on n(Ba)/n(Ca) and revisit published results for n(Sr)/n(Ca) in two white dwarfs that have accreted rocky planetesimals. We find that at most only a small fraction of the pollution is from crustal material that has experienced the distinctive elemental enhancements induced by Earth-analog plate tectonics. In view of the intense theoretical interest in the physical structure of extrasolar rocky planets, this search should be extended to additional targets.

Reference
Jura M, Klein B, Xu S (许偲艺), Young ED (2014) A Pilot Search for Evidence of Extrasolar Earth-analog Plate Tectonics. Astrophysical Journal Letters 791, L29.

Link to Article [doi:10.1088/2041-8205/791/2/L29]

¹ P. Vernazza, ^2,5,6 B. Zanda, ^3,7 R. P. Binzel, ⁴T. Hiroi, ³F. E. DeMeo, ⁵M. Birlan, ^2,6R. Hewins, ⁸L. Ricci, ¹P. Barge, ³M. Lockhart

¹ Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille, France
² Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités, Muséum National d’Histoire Naturelle, UPMC Université Paris 06, UMR CNRS 7590, IRD UMR 206, 61 rue Buffon, F-75005 Paris, France
³ Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
⁴ Department of Geological Sciences, Brown University, Providence, RI 02912, USA
⁵ IMCCE, Observatoire de Paris, 77 Av. Denfert Rochereau, F-75014 Paris Cedex, France
⁶ Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
⁷ Chercheur Associé, IMCCE, Observatoire de Paris, 77 Av. Denfert Rochereau, F-75014 Paris Cedex, France
⁸ California Institute of Technology, MC 249-17, Pasadena, CA, 91125, USA

Although petrologic, chemical, and isotopic studies of ordinary chondrites and meteorites in general have largely helped establish a chronology of the earliest events of planetesimal formation and their evolution, there are several questions that cannot be resolved via laboratory measurements and/or experiments alone. Here, we propose the rationale for several new constraints on the formation and evolution of ordinary chondrite parent bodies (and, by extension, most planetesimals) from newly available spectral measurements and mineralogical analysis of main-belt S-type asteroids (83 objects) and unequilibrated ordinary chondrite meteorites (53 samples). Based on the latter, we suggest that spectral data may be used to distinguish whether an ordinary chondrite was formed near the surface or in the interior of its parent body. If these constraints are correct, the suggested implications include that: (1) large groups of compositionally similar asteroids are a natural outcome of planetesimal formation and, consequently, meteorites within a given class can originate from multiple parent bodies; (2) the surfaces of large (up to ~200 km) S-type main-belt asteroids mostly expose the interiors of the primordial bodies, a likely consequence of impacts by small asteroids (D < 10 km) in the early solar system; (3) the duration of accretion of the H chondrite parent bodies was likely short (instantaneous or in less than ~105 yr, but certainly not as long as 1 Myr); (4) LL-like bodies formed closer to the Sun than H-like bodies, a possible consequence of the radial mixing and size sorting of chondrules in the protoplanetary disk prior to accretion.

Reference
Vernazza P, Zanda B, Binzel RP, Hiroi T, DeMeo FE, Birlan M, Hewins R, Ricci L, Barge P, Lockhart M (2014) Multiple and Fast: The Accretion of Ordinary Chondrite Parent Bodies. The Astrophysical Journal 791, 120.

Link to Article [doi:10.1088/0004-637X/791/2/120]