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Can ^(59)Ni Synthesized in OB Associations Decay to ^(59)Co Before Being Accelerated to Cosmic-ray Energies

Binns, W. R. and Cummings, A. C. and de Nolfo, G. A. and Israel, M. H. and Leske, R. A. and Mewaldt, R. A. and von Rosenvinge, T. T. and Stone, E. C. and Wiedenbeck, M. E. (2007) Can ^(59)Ni Synthesized in OB Associations Decay to ^(59)Co Before Being Accelerated to Cosmic-ray Energies. In: Proceedings of the 30th International Cosmic Ray Conference. Vol.2. Universidad Nacional Autónoma de México , Merida, Yucatan, Mexico, pp. 27-30.

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Observations from the Cosmic Ray Isotope Spectrometer (CRIS) aboard NASA’s Advanced Composition Explorer (ACE) have shown that all relevant galactic cosmic-ray isotopic ratios measured are consistent with an OB-association origin of galactic cosmic rays (GCRs). Additionally CRIS measurements of the isotopic abundances of ^(59)Ni and ^(59)Co have shown that the ^(59)Ni has completely decayed into ^(59)Co, indicating a delay of >105 years between nucleosynthesis and acceleration. However, it has been suggested that shocks generated from high-velocity Wolf-Rayet winds in the OB-association environment must accelerate nuclei synthesized in nearby core-collapse supernovae on a time scale short compared to the ^(59)Ni half-life of 7.6x10^4 years. If this were the case, it would imply that OB associations could not be the source of most galactic cosmic rays. In this paper, we describe the OB-association history and environment and show that the time scales for acceleration are such that most ^(59)Ni should be expected to decay naturally in that setting, strengthening the argument that OB associations are the likely source of a substantial fraction of galactic cosmic rays.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Binns, W. R.0000-0001-6110-3407
Cummings, A. C.0000-0002-3840-7696
de Nolfo, G. A.0000-0002-3677-074X
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
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:Copyright Universidad Nacional Autónoma de México This research was supported by NASA at Caltech, WU, the JPL, and GSFC (under Grants NAG5-6912 and NAG5-12929).
Group:Space Radiation Laboratory
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2008-11
Record Number:CaltechAUTHORS:20150415-153704362
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56696
Deposited By: Deborah Miles
Deposited On:16 Apr 2015 15:55
Last Modified:09 Mar 2020 13:19

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