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Wolf-Rayet stars, OB associations, 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) Wolf-Rayet stars, OB associations, and the origin of galactic cosmic rays. New Astronomy Reviews, 50 (7-8). pp. 516-520. ISSN 1387-6473. doi:10.1016/j.newar.2006.06.058.

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We have measured the isotopic abundances of neon and several refractory species in the galactic cosmic rays (GCRs) using the cosmic ray isotope spectrometer (CRIS) aboard the ACE spacecraft. The ^(22)Ne/^(20)Ne ratio at the cosmic-ray source that we have obtained is 0.387 ± 0.007 (stat.) ± 0.022 (syst.), which corresponds to enhancement by a factor of 5.3 ± 0.3 over that in the solar wind. Our ACE-CRIS data, and data from other experiments, are compared to recent results from two-component Wolf-Rayet (WR) models. The three largest deviations of galactic cosmic ray isotope ratios from solar-system ratios predicted by these models, ^(12)C/^(16)O,^(22)Ne/^(20)Ne, and ^(58)Fe/^(56)Fe, are, in fact, very close to those observed. Furthermore, all of the isotope ratios that we have measured are consistent with a GCR source consisting of ~20% of WR material mixed with ~80% material with solar-system composition. Since WR stars are evolutionary products of OB stars, and most OB stars exist in OB associations that form superbubbles, the good agreement of our data with WR models suggests that OB associations within 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
Wiedenbeck, M. E.0000-0002-2825-3128
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:© 2006 Elsevier B.V. Available online 24 July 2006. The authors wish to thank N. Prantzos, S. Woosley, and A. van Marle for helpful discussions. This research was supported in part by the National Aeronautics and Space Administration at Caltech, Washington University, the Jet Propulsion Laboratory, and Goddard Space Flight Center (under Grants NAG5-6912 and NAG5-12929).
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Goddard Space FlightNAG5-6912
Goddard Space FlightNAG5-12929
Washington UniversityUNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2006-13
Issue or Number:7-8
Classification Code:PACS: 98.70.Sa: Cosmic rays; 97.30.Eh: WR stars; 98.20.AF: OB associations
Record Number:CaltechAUTHORS:20110120-162201593
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21840
Deposited By: Benjamin Perez
Deposited On:24 Jan 2011 15:54
Last Modified:09 Nov 2021 16:00

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