Jupiter’s Synchrotron Radiation Mapped with the Very Large Array from 1981 to 1998

Kloosterman, Jenna; Dunn, D. E.; Pater, Imke de

doi:10.1086/491601

Cited by 10 publications

(17 citation statements)

References 18 publications

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“…The D E dependence of the averaged dawn‐dusk ratio. Each data points was obtained by fitting the cubic sine function to Figure in Kloosterman et al [] (reproduced by permission of the AAS). The averaged dawn‐dusk ratio has a clear D E dependence, but it always exceeds unity.…”

Section: Discussionmentioning

confidence: 99%

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Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

et al. 2013

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[1] We analyzed the Very Large Array archived data observed in 2000 to determine whether solar ultraviolet (UV)/extreme ultraviolet (EUV) heating of the Jovian thermosphere causes variations in the total flux density and dawn-dusk asymmetry (the characteristic differences between the peak emissions at dawn and dusk) of Jupiter's synchrotron radiation (JSR). The total flux density varied by 10% over 6 days of observations and accorded with theoretical expectations. The average dawn-dusk peak emission ratio indicated that the dawn side emissions were brighter than those on the dusk side and this was expected to have been caused by diurnal wind induced by the solar UV/EUV. The daily variations in the dawn-dusk ratio did not correspond to the solar UV/EUV, and this finding did not support the theoretical expectation that the dawn-dusk ratio and diurnal wind velocity varies in correspondence with the solar UV/EUV. We tried to determine whether the average dawn-dusk ratio could be explained by a reasonable diurnal wind velocity. We constructed an equatorial brightness distribution model of JSR using the revised Divine-Garrett particle distribution model and used it to derive a relation between the dawn-dusk ratio and diurnal wind velocity. The estimated diurnal wind velocity reasonably corresponded to a numerical simulation of the Jovian thermosphere. We also found that realistic changes in the diurnal wind velocity could not cause the daily variations in the dawn-dusk ratio. Hence, we propose that the solar UV/EUV related variations were below the detection limit and some other processes dominated the daily variations in the dawn-dusk ratio.Citation: Kita, H., H. Misawa, F. Tsuchiya, C. Tao, and A. Morioka (2013), Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation,

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Section: Discussionmentioning

confidence: 99%

“…The P‐band entries correspond to the VLA 327 MHz data analyzed in this study, and the L‐band entries correspond to the data for the D E =0 case from Kloosterman et al [].…”

Section: Discussionmentioning

confidence: 99%

Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

et al. 2013

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“…It is well known that Jupiter's brightness distribution changes with D E (Dulk et al 1999;Kloosterman et al 2005 (Sault et al 1995). To only map Jupiter's synchrotron radiation, limb-darkened disk models with blackbody temperatures of 525 and 350 K (de Pater 1990, p. 361, Fig.…”

Section: Observations and Data Processingmentioning

confidence: 99%

“…The resolving beam size, therefore, varies from observation period to observation period (Table 2). This approach enables us to properly discern the differences in the Jovian synchrotron when the distance separating Earth and Jupiter varies between observation periods (e.g., Kloosterman et al 2005). We also scale all data to a standard Earth-Jupiter distance of 4.04 AU by multiplying all intensities by (δ ej /4.04) 2 , with δ ej the geocentric distance at the time of the observations (Table 1).…”

Section: Observations and Data Processingmentioning

confidence: 99%

Multifrequency analysis of the Jovian electron-belt radiation during theCassiniflyby of Jupiter

Santos-Costa

Pater

Sault

et al. 2014

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Aims. We examine Very Large Array (VLA) observations of Jupiter to present evidence of fluctuations in the emission produced by the electron belt in January 2001. Investigating the source of fluctuations will provide new opportunities to discuss the scenarios of temporal changes in Jupiter's synchrotron radiation (i.e., the electron belt) in future data analysis and modeling work. Methods. To discuss the electron belt dynamics during the Cassini flyby of Jupiter, we compare the radio measurements from 2−3 January 2001 with VLA observations obtained on 20−21 December 1988, when viewing geometry and array configuration are comparable. All data are scaled to a standard Earth-Jupiter distance of 4.04 AU for comparison purposes. Brightness distribution maps with identical spatial resolutions and cartography of the equatorial radiation are constructed and examined at the wavelengths of ∼21 cm and ∼90 cm. Results. Rotation-averaged maps show that the emission from the equatorial zones of maximum intensity is weaker by ∼5−40%, but the brightness distribution is spatially more extended on 2−3 January 2001, resulting in a total emission at both wavelengths stronger by ∼35%. Between observation periods, the brightness distributions are observed to evolve differently during the planet rotation. Tomographic reconstructions of the equatorial radiation support our conclusion that the electron-belt population was differently distributed around the planet in December 1988 and January 2001. Conclusions. Our analysis of VLA data sets suggests that the spatial distribution of the electron belt on 2−3 January 2001 is different from that usually observed. Our knowledge of solar activity at the time of the Cassini flyby of Jupiter suggests that the emission from the electron radiation belt was responding to external influences, most likely to solar wind structures rather than to solar radio flux, on a timescale of days to a couple of weeks. Combined results from a multisource data analysis -including spacecraft and radio observations -are needed to confirm this relationship.

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“…The Earth declination as seen from Jupiter, D E , varies slowly over a 11.9‐year cycle between the limit values of −3.3° and +3.3°. The effects of this parameter on Jupiter's decimetric emission had been investigated by carrying out data analysis of single dish and interferometric measurements but also by combining models of the electron radiation belt with synchrotron simulation codes or using a 3D Fourier mapping technique to construct the tridimensional structure of the synchrotron radiation [ de Pater and Klein , 1989; Klein et al , 1989; Hood , 1993; Dulk et al , 1997b, 1999a; Leblanc et al , 1997b; Dunn et al , 2003; Sicard et al , 2004; Kloosterman et al , 2005; Santos‐Costa et al , 2008, and references therein]. Data analyses and modeling works have both led to the conclusion that D E cannot induce drastic changes in the appearance of the 2‐D brightness distribution and distorts efficiently the longitudinal profile of the total flux density over periods of time lasting less than a few months.…”

Section: Origins Of Short‐term Variationsmentioning

confidence: 99%

VLA observations at 6.2 cm of the response of Jupiter's electron belt to the July 2009 event

et al. 2011

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We present and analyze observations made with the Very Large Array in 2009. The observations show significant fluctuations in the emission radiated by Jupiter's electron belt between July and September. Intensity variations of 10 up to 40% in the radiation at 6.2 cm were found to be too important to be the results of data errors. The numerical reconstruction of equatorial brightness distributions indicates that the fluctuations were related to the 2009 July impact. The computed tomographic‐like maps demonstrate that the formation and subsequent longitudinal dispersion and change in intensity of an impact‐related synchrotron “hot spot” were the cause of the fluctuations. By examining the time profile of the longitude‐averaged total flux density, we find that the changes in the radiation‐belt emission lasted for about 100 days.

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Jupiter’s Synchrotron Radiation Mapped with the Very Large Array from 1981 to 1998

Cited by 10 publications

References 18 publications

Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

Multifrequency analysis of the Jovian electron-belt radiation during theCassiniflyby of Jupiter

VLA observations at 6.2 cm of the response of Jupiter's electron belt to the July 2009 event

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