@Article{RoussosKDKPEMK:2019:CoCaOb,
author = "Roussos, Elias and Krupp, Norbert and Dialynas, Konstantinos and
Kollmann, Peter and Paranicas, Christopher and Echer, Ezequiel and
Mitchell, Donald G. and Krimigis, Stamatios M.",
affiliation = "{Max Planck Institute for Solar System Research} and {Max Planck
Institute for Solar System Research} and Office of Space Research
and Technology, Academy of Athens and {Johns Hopkins University
Applied Physics Laboratory} and {Johns Hopkins University Applied
Physics Laboratory} and {Instituto Nacional de Pesquisas Espaciais
(INPE)} and {Johns Hopkins University Applied Physics Laboratory}
and Office of Space Research and Technology, Academy of Athens",
title = "Jovian cosmic-ray protons in the heliosphere: constraints by
cassini observations",
journal = "Astrophysical Journal",
year = "2019",
volume = "871",
number = "2",
pages = "e223",
month = "Feb.",
keywords = "cosmic rays, planets and satellites: gaseous planets, Sun:
heliosphere.",
abstract = "Measurements of >82 MeV Galactic cosmic-ray (GCR) protons at Earth
indicate that they may be mixed with protons that leak into the
heliosphere from Jupiter's magnetosphere (Jovian cosmic-ray
protons (JCRPs)). A similar to 400 day periodicity in these proton
fluxes, which is similar to the synodic period between Jupiter and
Earth, and an excess proton flux observed when Jupiter and Earth
can be connected through the interplanetary magnetic field were
the basis for this claim. Using nearly 13 yr of GCR measurements
at Saturn with Cassini's Magnetosphere Imaging Instrument, we show
that the similar to 400 day periodicity is also present in greater
than or similar to 100 MeV protons at similar to 9.6 au, although
the synodic period between Saturn and Jupiter is similar to 20 yr.
We also find that the features responsible for this periodicity
were convected from 1 au to Saturn's distance with the solar wind
velocity. Their origin is therefore heliospheric, not Jovian. We
attribute these features to quasi-biennial oscillations, observed
in the solar magnetic field and various heliospheric indices. This
finding indicates that fluxes of JCRPs at 1 au, if present, are
considerably overestimated, because the signal originally
attributed to them represents the amplitude of the similar to 400
day periodic GCR oscillation. This oscillation has to be
subtracted before the resulting proton GCR flux residuals are
analyzed in the context of a possible Jovian source. A
confirmation of the presence of JCRPs over extended regions in the
heliosphere and a constraint on their fractional abundance in GCR
spectra may therefore require further validation and analysis, and
several options are proposed for this purpose.",
doi = "10.3847/1538-4357/aafb2f",
url = "http://dx.doi.org/10.3847/1538-4357/aafb2f",
issn = "0004-637X and 1538-4357",
language = "en",
targetfile = "roussos_jovian.pdf",
urlaccessdate = "27 abr. 2024"
}