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Superbubbles, Wolf-Rayet stars, and the origin of galactic cosmic rays

Binns, W. R. and Wiedenbeck, M. E. and Arnould, M. and Cummings, A. C. and George, J. S. and Goriely, S. and Israel, M. H. and Leske, R. A. and Mewaldt, R. A. and Meynet, G. and Scott, L. M. and Stone, E. C. and von Rosenvinge, T. T. (2006) Superbubbles, Wolf-Rayet stars, and the origin of galactic cosmic rays. Journal of Physics: Conference Series, 47 . pp. 68-77. ISSN 1742-6596.

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The abundances of neon and several other isotopic ratios in the galactic cosmic rays (GCRs) have been measured using data from the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE). We have derived the 22Ne/20Ne ratio at the cosmic-ray source using the measured 21Ne, 19F, and 17O abundances as "tracers" of secondary isotope production. Using this approach, the 22Ne/20Ne abundance ratio obtained for the cosmic-ray source is 0.387 ± 0.007 (stat.) ± 0.022 (syst.). This corresponds to an enhancement by a factor of 5.3±0.3 over the 22Ne/20Ne ratio in the solar wind. We compare our data for neon and refractory isotope ratios, and data from other experiments, with recent results from two-component Wolf-Rayet (WR) models. The three largest deviations of GCR isotope ratios from solar system ratios predicted by these models, 12C/16O, 22Ne/20Ne, and 58Fe/56Fe, are present in the GCRs. In fact, all of the isotope ratios that we have measured are consistent with a GCR source consisting of about 80% material with solar-system composition and about 20% of WR material. Since WR stars are evolutionary products of O and B stars, and most OB stars exist in OB associations that form superbubbles, the good agreement of these data with WR models suggests that superbubbles are the likely source of at least a substantial fraction of GCRs.

Item Type:Article
Related URLs:
URLURL TypeDescription
Binns, W. R.0000-0001-6110-3407
Cummings, A. C.0000-0002-3840-7696
Israel, M. H.0000-0002-8104-208X
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Additional Information:Copyright © Institute of Physics and IOP Publishing Limited 2006. We wish to thank Katharina Lodders of Washington University for helpful discussions on the fraction of elements tied up in grains in the Solar System interplanetary medium. In addition, we wish to thank Sachico Amari for helpful discussions on neon in meteorites. This research was supported by the National Aeronautics and Space Administration at the California Institute of Technology (under grants NAG5-6912 and NAG5-12929), Washington University, the Jet Propulsion Laboratory, and the Goddard Space Flight Center. Physics at the end of the galactic cosmic ray spectrum, Aspen, Colorado, USA, 26–30 April 2005. Journal of Physics: Conference Series, Volume 47, 2006
Group:Space Radiation Laboratory
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Space Radiation Laboratory2006-14
Record Number:CaltechAUTHORS:BINjpcs06
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ID Code:6909
Deposited By: Archive Administrator
Deposited On:02 Jan 2007
Last Modified:09 Mar 2020 13:18

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