%0 Journal Article %T PROTOSOLAR CARBON ISOTOPIC COMPOSITION: IMPLICATIONS FOR THE ORIGIN OF METEORITIC ORGANICS %+ Osaka University [Osaka] %+ Centre de Recherches Pétrographiques et Géochimiques (CRPG) %+ Hiroshima University %A Hashizume, Ko %A Chaussidon, Marc %A Marty, Bernard %A Terada, Kentaro %< avec comité de lecture %@ 0004-637X %J The Astrophysical Journal %I American Astronomical Society %V 600 %P 480-484 %8 2003 %D 2003 %Z Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]Journal articles %X New ion probe isotopic measurements of carbon trapped within the 50 nm thick surface layer of lunar regolith grains strongly suggest that solar wind C is depleted in 13 C by at least 10% relative to terrestrial C. In order to account for the general 13 C enrichment of planetary C relative to solar C, we propose that the main carriers of C in these objects, i.e., organics, were formed in an environment that allowed a strong isotopic enrichment of 13 C in the solid phase. Such an environment is most likely a dense and warm circumstellar or interstellar gas medium, which could well correspond to the nebula surrounding the proto-Sun, where isotopic fractionation could be triggered by photochemical reactions. %G English %2 https://insu.hal.science/insu-01882002/document %2 https://insu.hal.science/insu-01882002/file/Hashizume_2004_ApJ_600_480.pdf %L insu-01882002 %U https://insu.hal.science/insu-01882002 %~ INSU %~ CNRS %~ UNIV-LORRAINE %~ OTELO-UL %~ CRPG-UL %~ TEST3-HALCNRS