Pub Date : 2007-12-13DOI: 10.1080/10556790701610282
A. D. Kuz’min, B. Losovsky
We report the low frequency measurements of the scatter pulse broadening τsc for a large sample of 100 pulsars in a vast Galaxy region of galactic longitudes from 6° to 311° and distances up to 3 kpc. Analysis of τsc dependencies on the frequency, dispersion measure, distance and Galactic longitude have been done. The scatter to frequency dependence can be presented by the power-low relation τsc(ν) ∝ ν−γ with γ=4.1±0.3. Up to a distance of 3 kpc the scatter to dispersion measure dependence can be presented by the power-low relation τsc(DM) ∝ DM2.2±0.1. The turbulence level is nearly identical in various directions and distances of the near Galaxy, testifying to the statistical homogeneity of a large-scale plasma turbulence in this Galaxy region.
{"title":"Measurements of the scattering of pulsars radio emission. Statistical uniformity of large-scale plasma turbulence in the near Galaxy","authors":"A. D. Kuz’min, B. Losovsky","doi":"10.1080/10556790701610282","DOIUrl":"https://doi.org/10.1080/10556790701610282","url":null,"abstract":"We report the low frequency measurements of the scatter pulse broadening τsc for a large sample of 100 pulsars in a vast Galaxy region of galactic longitudes from 6° to 311° and distances up to 3 kpc. Analysis of τsc dependencies on the frequency, dispersion measure, distance and Galactic longitude have been done. The scatter to frequency dependence can be presented by the power-low relation τsc(ν) ∝ ν−γ with γ=4.1±0.3. Up to a distance of 3 kpc the scatter to dispersion measure dependence can be presented by the power-low relation τsc(DM) ∝ DM2.2±0.1. The turbulence level is nearly identical in various directions and distances of the near Galaxy, testifying to the statistical homogeneity of a large-scale plasma turbulence in this Galaxy region.","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81009584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701600515
I. Chashei, A. Efimov, M. Bird
Properties of plasma turbulence in the solar wind can be determined from radio frequency fluctuation measurements recorded during solar conjunctions. Noteworthy recent results were obtained from radio occultation experiments performed with the spacecraft Galileo in the interval 1994–2002 and Ulysses in 1991–1997. The power spectral index was calculated for the range of heliocentric distances 5 RS
{"title":"Solar wind turbulence from radio occultation data","authors":"I. Chashei, A. Efimov, M. Bird","doi":"10.1080/10556790701600515","DOIUrl":"https://doi.org/10.1080/10556790701600515","url":null,"abstract":"Properties of plasma turbulence in the solar wind can be determined from radio frequency fluctuation measurements recorded during solar conjunctions. Noteworthy recent results were obtained from radio occultation experiments performed with the spacecraft Galileo in the interval 1994–2002 and Ulysses in 1991–1997. The power spectral index was calculated for the range of heliocentric distances 5 RS<R<80 RS(RS = solar radius) and the radial evolution of this parameter is discussed. Galileo data (at low solar latitudes) are compared with those recorded with Ulysses (high heliographic latitudes) during the solar activity minimum. Estimates of the turbulence outer scale are obtained using long Galileo frequency fluctuation records. It is found that the turbulence outer scale increases approximately linearly with increasing solar distance in the inner region of the developed solar wind. The observations are interpreted under the assumption that the density fluctuations are generated locally via nonlinear interac...","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78929013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701610290
A. Afanasiev
Abstract The influence of strong regular refraction (that leads to regular caustics and multipathing) in the solar corona on the structure of radio emission scattered by coronal turbulence is investigated. Distant cosmic sources and Sun's own radio sources are considered. It is shown that observations of the energy spectrum of spacecraft radio signals and of the mean profile of a pulsar pulse in the Sun's caustic shadow zone can be used for coronal turbulence diagnostics. It is also shown that strong regular refraction plays an important role in formation of solar millisecond spike bursts and of type IIId solar decameter radio bursts with echo components.
{"title":"Coronal scattering of radio emission under strong regular refraction","authors":"A. Afanasiev","doi":"10.1080/10556790701610290","DOIUrl":"https://doi.org/10.1080/10556790701610290","url":null,"abstract":"Abstract The influence of strong regular refraction (that leads to regular caustics and multipathing) in the solar corona on the structure of radio emission scattered by coronal turbulence is investigated. Distant cosmic sources and Sun's own radio sources are considered. It is shown that observations of the energy spectrum of spacecraft radio signals and of the mean profile of a pulsar pulse in the Sun's caustic shadow zone can be used for coronal turbulence diagnostics. It is also shown that strong regular refraction plays an important role in formation of solar millisecond spike bursts and of type IIId solar decameter radio bursts with echo components.","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74363423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701596200
M. Kojima, M. Tokumaru, K. Fujiki, Keiji Hayashi, B. Jackson
Interplanetary scintillation (IPS) observations have been improved by development of deconvolution methods for the line-of-sight integration effect. One deconvolution method is to use a computer-assisted tomographic analysis (CAT) technique. In this work, four different kinds of CAT method have been developed. Two of them can be applied to stable solar wind structure in the solar minimum phase, one to quasi-stable solar wind, and the other can derive the three-dimensional structure of transient solar wind events, such as a CME. IPS measurements have enough spatial resolution and accuracy to collaborate with spacecraft observations and theoretical studies of the solar wind. Here, these computer assisted tomographic deconvolution methods are introduced and their application to solar wind studies is described.
{"title":"IPS tomographic observations of 3D solar wind structure","authors":"M. Kojima, M. Tokumaru, K. Fujiki, Keiji Hayashi, B. Jackson","doi":"10.1080/10556790701596200","DOIUrl":"https://doi.org/10.1080/10556790701596200","url":null,"abstract":"Interplanetary scintillation (IPS) observations have been improved by development of deconvolution methods for the line-of-sight integration effect. One deconvolution method is to use a computer-assisted tomographic analysis (CAT) technique. In this work, four different kinds of CAT method have been developed. Two of them can be applied to stable solar wind structure in the solar minimum phase, one to quasi-stable solar wind, and the other can derive the three-dimensional structure of transient solar wind events, such as a CME. IPS measurements have enough spatial resolution and accuracy to collaborate with spacecraft observations and theoretical studies of the solar wind. Here, these computer assisted tomographic deconvolution methods are introduced and their application to solar wind studies is described.","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81111638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701614862
D. Stinebring
It is well known that pulsar dynamic spectra occasionally show pronounced fringing or criss-cross patterns. It was a surprise, however, that a two-dimensional Fourier analysis of these spectra showed faint, parabolic features, which are now called scintillation arcs. I will show evidence that the scintillation arc phenomenon is widespread and that it underpins many other scintillation phenomena. If an estimate of the distance to the pulsar and a measurement of its proper motion exist, then the location of the scattering material along the line of sight can be determined. There is often pronounced substructure in the arcs, and it translates along the main arc in a manner that is determined by the proper motion of the pulsar. This substructure may be produced by lens-like features in the ionized interstellar medium that are far out of pressure balance with the warm ionized medium and that may be related to deterministic structures that cause extreme scattering events. Observations with this technique, which...
{"title":"Using pulsar scintillation to probe AU-size structure in the interstellar medium","authors":"D. Stinebring","doi":"10.1080/10556790701614862","DOIUrl":"https://doi.org/10.1080/10556790701614862","url":null,"abstract":"It is well known that pulsar dynamic spectra occasionally show pronounced fringing or criss-cross patterns. It was a surprise, however, that a two-dimensional Fourier analysis of these spectra showed faint, parabolic features, which are now called scintillation arcs. I will show evidence that the scintillation arc phenomenon is widespread and that it underpins many other scintillation phenomena. If an estimate of the distance to the pulsar and a measurement of its proper motion exist, then the location of the scattering material along the line of sight can be determined. There is often pronounced substructure in the arcs, and it translates along the main arc in a manner that is determined by the proper motion of the pulsar. This substructure may be produced by lens-like features in the ionized interstellar medium that are far out of pressure balance with the warm ionized medium and that may be related to deterministic structures that cause extreme scattering events. Observations with this technique, which...","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91123824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701600218
V. Shishov
Basic theoretical methods and solutions describing radio wave propagation in the turbulent plasma are briefly reviewed. Consideration is given to the results on scattering effects such as angular scattering, pulse broadening and spectral line spread. Also treated are phase and frequency fluctuations. Of particular concern are problems of the correlation theory of intensity fluctuations for weak and strong diffractive and refractive scintillations. Special attention is paid to the effect of refractive scintillation on a diffractive pattern.
{"title":"Review of theory of interplanetary and interstellar scintillation","authors":"V. Shishov","doi":"10.1080/10556790701600218","DOIUrl":"https://doi.org/10.1080/10556790701600218","url":null,"abstract":"Basic theoretical methods and solutions describing radio wave propagation in the turbulent plasma are briefly reviewed. Consideration is given to the results on scattering effects such as angular scattering, pulse broadening and spectral line spread. Also treated are phase and frequency fluctuations. Of particular concern are problems of the correlation theory of intensity fluctuations for weak and strong diffractive and refractive scintillations. Special attention is paid to the effect of refractive scintillation on a diffractive pattern.","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74602003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701595236
M. Bird
Faraday rotation (FR) observations of radio sources near solar conjunction yield information on the coronal magnetic field at heliospheric distances not reached by in situ exploration. Measurements of FR yield the rotation measure (RM), a wavelength independent quantity defined as the integral along the raypath of the product of the electron density times the raypath-parallel component of the magnetic field. Independent observations or models of the coronal electron density are required in order to extract information about the magnetic field. The radio sounding sources can be either artificial (spacecraft) or natural, but they must be at least partially linearly polarized. The most extensive campaign of coronal radio sounding polarization measurements using a spacecraft was the Helios Faraday Rotation Experiment, which was conducted over the duration of the Helios 1 (1974–1984) and Helios 2 (1976–1980) missions. Other coronal FR experiments have been carried out using natural continuum sources recently a...
{"title":"Coronal Faraday rotation of occulted radio signals","authors":"M. Bird","doi":"10.1080/10556790701595236","DOIUrl":"https://doi.org/10.1080/10556790701595236","url":null,"abstract":"Faraday rotation (FR) observations of radio sources near solar conjunction yield information on the coronal magnetic field at heliospheric distances not reached by in situ exploration. Measurements of FR yield the rotation measure (RM), a wavelength independent quantity defined as the integral along the raypath of the product of the electron density times the raypath-parallel component of the magnetic field. Independent observations or models of the coronal electron density are required in order to extract information about the magnetic field. The radio sounding sources can be either artificial (spacecraft) or natural, but they must be at least partially linearly polarized. The most extensive campaign of coronal radio sounding polarization measurements using a spacecraft was the Helios Faraday Rotation Experiment, which was conducted over the duration of the Helios 1 (1974–1984) and Helios 2 (1976–1980) missions. Other coronal FR experiments have been carried out using natural continuum sources recently a...","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90764775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701614821
S. Molodykh
Abstract The non-thermal broadening of coronal lines observed within short distances from the Sun was analysed and analysis revealed that near the Sun this broadening is caused by Alfven waves. Within the magnetohydrodynamic (MHD) approximation, the wave energy flux required for solar wind formation, and also the plasma velocity and temperature were calculated. Electron density distributions and flow geometry were used as input data. It is shown that the energy flux required for solar wind formation enters the solar corona in the form of Alfven waves and the dissipation of these waves provides the heating of the solar wind plasma near the Sun. The transformation of Alfven waves to acoustic waves in this region is less effective than their dissipation. The dissipation of the Alfven waves falls off with distance from the Sun, and the heating of the solar wind plasma is determined by the coefficient of transformation of the Alfven waves to acoustic waves. Subsequently, the dissipation effectiveness of the ac...
{"title":"An Analysis of the energy balance in the solar wind formation region","authors":"S. Molodykh","doi":"10.1080/10556790701614821","DOIUrl":"https://doi.org/10.1080/10556790701614821","url":null,"abstract":"Abstract The non-thermal broadening of coronal lines observed within short distances from the Sun was analysed and analysis revealed that near the Sun this broadening is caused by Alfven waves. Within the magnetohydrodynamic (MHD) approximation, the wave energy flux required for solar wind formation, and also the plasma velocity and temperature were calculated. Electron density distributions and flow geometry were used as input data. It is shown that the energy flux required for solar wind formation enters the solar corona in the form of Alfven waves and the dissipation of these waves provides the heating of the solar wind plasma near the Sun. The transformation of Alfven waves to acoustic waves in this region is less effective than their dissipation. The dissipation of the Alfven waves falls off with distance from the Sun, and the heating of the solar wind plasma is determined by the coefficient of transformation of the Alfven waves to acoustic waves. Subsequently, the dissipation effectiveness of the ac...","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91044653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701612221
B. Jackson, P. Hick, A. Buffington, M. Bisi, M. Kojima, M. Tokumaru
The Solar-Terrestrial Environment Laboratory (STELab), Japan, interplanetary scintillation (IPS) g-level and velocity measurements can be used to give the extent of CME disturbances in the interplanetary medium arising from the scattering of the radio waves from distant point-like natural sources through the intervening medium. In addition, white-light Thomson-scattering observations from the Solar Mass Ejection Imager (SMEI) have recorded the inner heliospheric response to several hundred CMEs. The work described here compares and details the difference in three-dimensional (3D) reconstructions for these two data sets for the well-observed 28 October 2003 halo CME seen in LASCO; this passed Earth on 29 October in the SMEI data at the same elongations as IPS g-level observations. The SMEI data analysis employs a 3D tomographic reconstruction technique that obtains perspective views from outward-flowing solar wind as observed from Earth, iteratively fitting a kinematic solar wind density model, and when av...
{"title":"Comparison of the extent and mass of CME events in the interplanetary medium using IPS and SMEI Thomson scattering observations","authors":"B. Jackson, P. Hick, A. Buffington, M. Bisi, M. Kojima, M. Tokumaru","doi":"10.1080/10556790701612221","DOIUrl":"https://doi.org/10.1080/10556790701612221","url":null,"abstract":"The Solar-Terrestrial Environment Laboratory (STELab), Japan, interplanetary scintillation (IPS) g-level and velocity measurements can be used to give the extent of CME disturbances in the interplanetary medium arising from the scattering of the radio waves from distant point-like natural sources through the intervening medium. In addition, white-light Thomson-scattering observations from the Solar Mass Ejection Imager (SMEI) have recorded the inner heliospheric response to several hundred CMEs. The work described here compares and details the difference in three-dimensional (3D) reconstructions for these two data sets for the well-observed 28 October 2003 halo CME seen in LASCO; this passed Earth on 29 October in the SMEI data at the same elongations as IPS g-level observations. The SMEI data analysis employs a 3D tomographic reconstruction technique that obtains perspective views from outward-flowing solar wind as observed from Earth, iteratively fitting a kinematic solar wind density model, and when av...","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85944294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-12-13DOI: 10.1080/10556790701610399
V. Gubenko, V. Andreev
The results of cross-correlation analysis of the amplitude fluctuations of radio waves of the λ = 32 cm band in seven sessions of radio occultation measurements of the northern polar atmosphere of the planet are presented. The existence of the cross-correlation of fluctuations (bχ � 0.6–0.7) is established in the altitude realizations in the interval 61.5–65.0 km for four different sessions of radio occultations. Inner layering is revealed in the upper layer of the clouds of the planet at altitudes of 61.5–65.0 km, which is specified by an enhanced turbulence of the atmosphere. It is found that the “lifetime” of the small-scale layered irregularities is no less than two days and that their horizontal extension in the meridional direction can exceed ∼130 km. A possible cause of the emergence of the layered structures inside the upper layer of the polar clouds of Venus is discussed.
{"title":"The identification of the fluctuation effects related to the turbulence and","authors":"V. Gubenko, V. Andreev","doi":"10.1080/10556790701610399","DOIUrl":"https://doi.org/10.1080/10556790701610399","url":null,"abstract":"The results of cross-correlation analysis of the amplitude fluctuations of radio waves of the λ = 32 cm band in seven sessions of radio occultation measurements of the northern polar atmosphere of the planet are presented. The existence of the cross-correlation of fluctuations (bχ � 0.6–0.7) is established in the altitude realizations in the interval 61.5–65.0 km for four different sessions of radio occultations. Inner layering is revealed in the upper layer of the clouds of the planet at altitudes of 61.5–65.0 km, which is specified by an enhanced turbulence of the atmosphere. It is found that the “lifetime” of the small-scale layered irregularities is no less than two days and that their horizontal extension in the meridional direction can exceed ∼130 km. A possible cause of the emergence of the layered structures inside the upper layer of the polar clouds of Venus is discussed.","PeriodicalId":52135,"journal":{"name":"Astronomical and Astrophysical Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82926601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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