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          Institute: MPI für Radioastronomie     Collection: Publikationen des MPI für Radioastronomie     Display Documents



ID: 125443.0, MPI für Radioastronomie / Publikationen des MPI für Radioastronomie
Jupiter's radio spectrum from 74 MHz up to 8 GHz
Authors:de Pater, I.; Butler, B. J.; Green, D. A.; Strom, R.; Millan, R.; Klein, M. J.; Bird, M. K.; Funke, O.; Neidhöfer, J.; Maddalena, R.; Sault, R. J.; Kesteven, M.; Smits, D. P.; Hunstead, R.
Language:English
Date of Publication (YYYY-MM-DD):2003-06
Title of Journal:Icarus
Journal Abbrev.:Icarus
Volume:163
Issue / Number:2
Start Page:434
End Page:448
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We carried out a brief campaign in September 1998 to determine Jupiter's radio spectrum at frequencies spanning a range from 74 MHz up to 8 GHz. Eleven different telescopes were used in this effort, each uniquely suited to observe at a particular frequency. We find that Jupiter's spectrum is basically flat shortwards of 1-2 GHz, and drops off steeply at frequencies greater than 2 GHz. We compared the 1998 spectrum with a spectrum (330 MHz-8 GHz) obtained in June 1994, and report a large difference in spectral shape, being most pronounced at the lowest frequencies. The difference seems to be linear with log(nu), with the largest deviations at the lowest frequencies (nu).We have compared our spectra with calculations of Jupiter's synchrotron radiation using several published models. The spectral shape is determined by the energy-dependent spatial distribution of the electrons in Jupiter's magnetic field, which in turn is determined by the detailed diffusion process across L-shells and in pitch angle, as well as energy-dependent particle losses. The spectral shape observed in September 1998 can be matched well if the electron energy spectrum at L = 6 is modeled by a double power law E-a (1 + (E/E-0))(-b), with a = 0.4, b = 3, E-0 = 100 MeV, and a lifetime against local losses To = 6 X 107 S. In June 1994 the observations can be matched equally well with two different sets of parameters: (1) a = 0.6, b = 3, E-0 = 100 MeV, tau(0) = 6 x 10(7) s, or (2) a = 0.4, b = 3, E-0 = 100 MeV, tau(0) = 8.6 x 10(6) s. We attribute the large variation in spectral shape between 1994 and 1998 to pitch angle scattering, coulomb scattering and/or energy degradation by dust in Jupiter's inner radiation belts. (C) 2003 Elsevier Science (USA). All rights reserved.
Free Keywords:Jupiter, magnetosphere, radio observations
Comment of the Author/Creator:Date: 2003, JUN
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Radioastronomie
External Affiliations:Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA.; Univ Calif Berkeley, Dept Earth & Planetary Sci, Berkeley, CA 94720 USA.; Natl Radio Astron Observ, Socorro, NM 87801 USA.; Univ Cambridge, Cavendish Lab, Mullard Radio Astron Observ, Cambridge CB3 0HE, England.; Univ Amsterdam, Inst Astron, Amsterdam, Netherlands.; Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA.; CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA.; Univ Bonn, Inst Radioastron, D-53121 Bonn, Germany.; Max Planck Inst Radioastron, D-53121 Bonn, Germany.; Natl Radio Astron Observ, Green Bank, WV 24944 USA.; CSIRO, Epping, NSW 2121, Australia.; Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia.
Identifiers:ISI:000183796000012 [ID No:1]
ISSN:0019-1035 [ID No:2]
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