Helium and Neon Abundances and Compositions in Cometary Matter
Physics and Astronomy
Materials trapped and preserved in comets date from the earliest history of the solar system. Particles captured by the Stardust spacecraft from comet 81P/Wild 2 are indisputable cometary matter available for laboratory study. Here we report measurements of noble gases in Stardust material. Neon isotope ratios are within the range observed in “phase Q,” a ubiquitous, primitive organic carrier of noble gases in meteorites. Helium displays 3He/4He ratios twice those in phase Q and in Jupiter's atmosphere. Abundances per gram are surprisingly large, suggesting implantation by ion irradiation. The gases are probably carried in high-temperature igneous grains similar to particles found in other Stardust studies. Collectively, the evidence points to gas acquisition in a hot, high ion-flux nebular environment close to the young Sun.
B. Marty, R.L. Palma, R.O. Pepin, L. Zimmermann, D.J. Schlutter, P.G. Burnard A.J. Westphal, C.J. Snead, S. Bajt, R.H. Becker and J.E Simones, 2008. Helium and Neon Abundances and Compositions in Cometary Matter. Science 319 (5859), 75-78.
Publisher's Copyright and Source
Copyright © 2008 American Association for the Advancement of Science. Article published by the American Association for the Advancement of Science in Science, volume 319, issue number 5859, January 4, 2008, pages 75-78. Available online: http://doi.org/10.1126/science.1148001.