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Wu SY, Ye SY, Fischer G, Taubenschuss U, Jackman CM, O'Dwyer E, Kurth WS, Yao S, Yao ZH, Menietti JD, Xu Y, Long MY, Cecconi B. Saturn Anomalous Myriametric Radiation, a New Type of Saturn Radio Emission Revealed by Cassini. GEOPHYSICAL RESEARCH LETTERS 2022; 49:e2022GL099237. [PMID: 36249464 PMCID: PMC9541930 DOI: 10.1029/2022gl099237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/28/2022] [Accepted: 08/01/2022] [Indexed: 06/16/2023]
Abstract
A new radio component namely Saturn Anomalous Myriametric Radiation (SAM) is reported. A total of 193 SAM events have been identified by using all the Cassini Saturn orbital data. SAM emissions are L-O mode radio emission and occasionally accompanied by a first harmonic in R-X mode. SAM's intensities decrease with increasing distance from Saturn, suggesting a source near Saturn. SAM has a typical central frequency near 13 kHz, a bandwidth greater than 8 kHz and usually drifts in frequency over time. SAM's duration can extend to near 11 hr and even longer. These features distinguish SAM from the regular narrowband emissions observed in the nearby frequency range, hence the name anomalous. The high occurrence rate of SAM after low frequency extensions of Saturn Kilometric Radiation and the SAM cases observed during compressions of Saturn's magnetosphere suggest a special connection to solar wind dynamics and magnetospheric conditions at Saturn.
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Affiliation(s)
- S. Y. Wu
- Department of Earth and Space SciencesSouthern University of Science and TechnologyShenzhenPeople's Republic of China
- LESIAObservatoire de ParisUniversité PSLCNRSSorbonne UniversitéUniversité de ParisMeudonFrance
| | - S. Y. Ye
- Department of Earth and Space SciencesSouthern University of Science and TechnologyShenzhenPeople's Republic of China
| | - G. Fischer
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - U. Taubenschuss
- Department of Space PhysicsInstitute of Atmospheric Physics of the Czech Academy of SciencesPragueCzechia
| | - C. M. Jackman
- School of Cosmic PhysicsDIAS Dunsink ObservatoryDublin Institute for Advanced StudiesDublinIreland
| | - E. O'Dwyer
- School of Cosmic PhysicsDIAS Dunsink ObservatoryDublin Institute for Advanced StudiesDublinIreland
| | - W. S. Kurth
- Department of Physics and AstronomyUniversity of IowaIowa CityIAUSA
| | - S. Yao
- School of Geophysics and Information TechnologyChina University of Geosciences (Beijing)BeijingPeople's Republic of China
| | - Z. H. Yao
- Key Laboratory of Earth and Planetary PhysicsInstitute of Geology and GeophysicsChinese Academy of SciencesBeijingPeople's Republic of China
| | - J. D. Menietti
- Department of Physics and AstronomyUniversity of IowaIowa CityIAUSA
| | - Y. Xu
- Key Laboratory of Earth and Planetary PhysicsInstitute of Geology and GeophysicsChinese Academy of SciencesBeijingPeople's Republic of China
| | - M. Y. Long
- Department of Space PhysicsSchool of Electronic InformationWuhan UniversityWuhanPeople's Republic of China
| | - B. Cecconi
- LESIAObservatoire de ParisUniversité PSLCNRSSorbonne UniversitéUniversité de ParisMeudonFrance
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Woodfield EE, Horne RB, Glauert SA, Menietti JD, Shprits YY, Kurth WS. Formation of electron radiation belts at Saturn by Z-mode wave acceleration. Nat Commun 2018; 9:5062. [PMID: 30498204 PMCID: PMC6265320 DOI: 10.1038/s41467-018-07549-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/07/2018] [Indexed: 11/16/2022] Open
Abstract
At Saturn electrons are trapped in the planet's magnetic field and accelerated to relativistic energies to form the radiation belts, but how this dramatic increase in electron energy occurs is still unknown. Until now the mechanism of radial diffusion has been assumed but we show here that in-situ acceleration through wave particle interactions, which initial studies dismissed as ineffectual at Saturn, is in fact a vital part of the energetic particle dynamics there. We present evidence from numerical simulations based on Cassini spacecraft data that a particular plasma wave, known as Z-mode, accelerates electrons to MeV energies inside 4 RS (1 RS = 60,330 km) through a Doppler shifted cyclotron resonant interaction. Our results show that the Z-mode waves observed are not oblique as previously assumed and are much better accelerators than O-mode waves, resulting in an electron energy spectrum that closely approaches observed values without any transport effects included.
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Affiliation(s)
- E E Woodfield
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK.
| | - R B Horne
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - S A Glauert
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - J D Menietti
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA, 52242, USA
| | - Y Y Shprits
- Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, 14473, Germany
- Institute for Physics and Astronomy, Universität Potsdam, 14469, Potsdam, Germany
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, 90095, USA
| | - W S Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA, 52242, USA
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Lamy L, Zarka P, Cecconi B, Prangé R, Kurth WS, Hospodarsky G, Persoon A, Morooka M, Wahlund JE, Hunt GJ. The low-frequency source of Saturn’s kilometric radiation. Science 2018; 362:362/6410/eaat2027. [DOI: 10.1126/science.aat2027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 09/04/2018] [Indexed: 11/02/2022]
Abstract
Understanding how auroral radio emissions are produced by magnetized bodies requires in situ measurements within their source region. Saturn’s kilometric radiation (SKR) has been widely used as a remote proxy of Saturn’s magnetosphere. We present wave and plasma measurements from the Cassini spacecraft during its ring-grazing high-inclination orbits, which passed three times through the high-altitude SKR emission region. Northern dawn-side, narrow-banded radio sources were encountered at frequencies of 10 to 20 kilohertz, within regions of upward currents mapping to the ultraviolet auroral oval. The kilometric waves were produced on the extraordinary mode by the cyclotron maser instability from 6– to 12–kilo–electron volt electron beams and radiated quasi-perpendicularly to the auroral magnetic field lines. The SKR low-frequency sources appear to be strongly controlled by time-variable magnetospheric electron densities.
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Menietti JD, Mutel RL, Schippers P, Ye SY, Gurnett DA, Lamy L. Analysis of Saturn kilometric radiation near a source center. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja017056] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- J. D. Menietti
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - R. L. Mutel
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - P. Schippers
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - S.-Y. Ye
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - D. A. Gurnett
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - L. Lamy
- LESIA, Observatoire de Paris; Université Paris Diderot, UPMC, CNRS; Meudon France
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Lamy L, Cecconi B, Zarka P, Canu P, Schippers P, Kurth WS, Mutel RL, Gurnett DA, Menietti D, Louarn P. Emission and propagation of Saturn kilometric radiation: Magnetoionic modes, beaming pattern, and polarization state. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010ja016195] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- L. Lamy
- Laboratoire d'Etudes et d'Instrumentation en Astrophysique, Observatoire de Paris; CNRS; Meudon France
- Space and Atmospheric Physics, Blackett Laboratory; Imperial College London; London UK
| | - B. Cecconi
- Laboratoire d'Etudes et d'Instrumentation en Astrophysique, Observatoire de Paris; CNRS; Meudon France
| | - P. Zarka
- Laboratoire d'Etudes et d'Instrumentation en Astrophysique, Observatoire de Paris; CNRS; Meudon France
| | - P. Canu
- Laboratoire de Physique des Plasmas; Palaiseau France
| | - P. Schippers
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - W. S. Kurth
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - R. L. Mutel
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - D. A. Gurnett
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - D. Menietti
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - P. Louarn
- Centre d'Etude Spatiale des Rayonnements, Université Paul Sabatier; CNRS; Toulouse France
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Lamy L, Zarka P, Cecconi B, Prangé R. Auroral kilometric radiation diurnal, semidiurnal, and shorter-term modulations disentangled by Cassini. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010ja015434] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- L. Lamy
- Space and Atmospheric Physics; Imperial College London; London UK
- LESIA, Observatoire de Paris; CNRS, UPMC, Université Paris Diderot; Meudon France
| | - P. Zarka
- LESIA, Observatoire de Paris; CNRS, UPMC, Université Paris Diderot; Meudon France
| | - B. Cecconi
- LESIA, Observatoire de Paris; CNRS, UPMC, Université Paris Diderot; Meudon France
| | - R. Prangé
- LESIA, Observatoire de Paris; CNRS, UPMC, Université Paris Diderot; Meudon France
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Ye SY, Menietti JD, Fischer G, Wang Z, Cecconi B, Gurnett DA, Kurth WS. Z mode waves as the source of Saturn narrowband radio emissions. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009ja015167] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sheng-Yi Ye
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - J. D. Menietti
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - G. Fischer
- Space Research Institute; Austrian Academy of Sciences; Graz Austria
| | - Z. Wang
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | | | - D. A. Gurnett
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
| | - W. S. Kurth
- Department of Physics and Astronomy; University of Iowa; Iowa City Iowa USA
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Lamy L, Cecconi B, Prangé R, Zarka P, Nichols JD, Clarke JT. An auroral oval at the footprint of Saturn's kilometric radio sources, colocated with the UV aurorae. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2009ja014401] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- L. Lamy
- LESIA, Observatoire de Paris, UPMC, CNRS; Université Paris Diderot; Meudon France
- Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
| | - B. Cecconi
- LESIA, Observatoire de Paris, UPMC, CNRS; Université Paris Diderot; Meudon France
| | - R. Prangé
- LESIA, Observatoire de Paris, UPMC, CNRS; Université Paris Diderot; Meudon France
| | - P. Zarka
- LESIA, Observatoire de Paris, UPMC, CNRS; Université Paris Diderot; Meudon France
| | - J. D. Nichols
- Department of Physics and Astronomy; University of Leicester; Leicester UK
| | - J. T. Clarke
- Center for Space Physics; Boston University; Boston Massachusetts USA
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