Latitude Distribution of Interplanetary Magnetic Field Lines Rooted in Active Regions

Dulk, G. A.; Steinberg, J. L.; Hoang, S.; Lecacheux, A.

doi:10.1007/978-94-009-4612-5_28

Cited by 31 publications

(28 citation statements)

References 2 publications

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“…Since Langmuir waves do not propagate away from their source region, this is significant evidence that the spacecraft intercepted the electron beams that produced the type III emission. This means that the interplanetary field lines bent down to the ecliptic between the source surface and 1 AU, in agreement with the statistical analysis of direction finding observations of type III bursts with the ISEE 3 spacecraft by Dulk et al (1986) and with Ulysses measurements of magnetic fields and energetic particles at high heliolatitudes (see review by Neugebauer 1999). The only way to avoid this conclusion is to ascribe the Langmuir waves to a different source than the type III emitting electron beams, and to consider the temporal association as chance coincidence.…”

Section: Latitudinal Evolution Of the Flux Tubes In Interplanetary Spacesupporting

confidence: 88%

Open magnetic flux tubes in the corona and the transport of solar energetic particles

Klein¹,

Krucker²,

Lointier³

et al. 2008

A&A

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We investigate how magnetic fields guide energetic particles through the corona into interplanetary space and eventually to a spacecraft near the Earth. A set of seven simple particle events is studied, where energetic electrons (30-500 keV; Wind spacecraft) or protons (5-55 MeV; SoHO) were released together with low-energy electron beams producing metric-to-kilometric type III emission. Imaging of the coronal (metre-wave) part of this emission with the Nançay Radioheliograph is used to identify the open flux tubes that guide these electrons -and by inference all particles detected at 1 AU. Open coronal field lines are also computed using potential magnetic field extrapolations, constrained by a source surface and by SoHO/MDI measurements in the photosphere (code by Schrijver and DeRosa). We find that in all events the type III radio sources lie in open flux tubes in the potential magnetic field extrapolations. The open flux tubes are rooted in small parts of the parent active region, covering a heliocentric angle of a few degrees in the photosphere. But they expand rapidly above the neighbouring closed magnetic structures and cover several tens of degrees in longitude on the source surface. Some of these open field lines are found to connect the parent active region to the footpoint of the nominal Parker spiral on the source surface, within the uncertainty of about ±10• inherent to the evaluation of its connection longitude. This is so even when the parent active region is as far as 50• away. In two cases where the coronal flux tubes point to high heliolatitudes, the detection of Langmuir waves at the Wind spacecraft in the ecliptic plane suggests that the interplanetary field lines curve down to the ecliptic before reaching 1 AU. We conclude that non-radial open flux tubes in the corona can transport particles over several tens of degrees in longitude even in simple impulsive particle events. In all events we studied, potential magnetic field models give an adequate description of these structures.

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Section: Latitudinal Evolution Of the Flux Tubes In Interplanetary Spacesupporting

confidence: 88%

Open magnetic flux tubes in the corona and the transport of solar energetic particles

Klein¹,

Krucker²,

Lointier³

et al. 2008

A&A

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“…A thorough documentation of these works at high frequencies was made by Poquérusse (1984). At lower frequencies, namely at the hectometer and kilometer wavelengths, the widespread visibility of the type III emission was reported by MacDowall (1982), Dulk et al (1985), and Lecacheux et al (1989), using longitudinally separated spacecraft in the ecliptic plane, ISEE-3 and Voyagers. The first stereoscopic directivity measurements were reported by Poquérusse et al (1996) and Hoang et al (1997), using comparisons of flux densities measured between the ARTEMIS ground-based radio spectrograph around 150 MHz and the radio receiver (1.25-940 kHz) on the Ulysses spacecraft at the highest frequencies.…”

Section: Introductionmentioning

confidence: 73%

The directivity of solar type III bursts at hectometer and kilometer wavelengths: Wind-Ulysses observations

Bonnin¹,

Hoang²,

Maksimović³

2008

A&A

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We investigate the directivity of solar type III radio bursts at hectometer and kilometer wavelengths using radio data recorded simultaneously by the Wind and Ulysses spacecraft which are widely separated in heliocentric longitude and latitude. From the positions of the associated flares and the solar wind speed and plasma density measured aboard the spacecraft, we estimate the location of the type III radio sources along the approximately spiral magnetic field lines connected to the flare sites. Using the ratios of the radio flux densities measured from 1995 to 2005 at the same frequencies (940-80 kHz) on these spacecraft, we have for the first time derive the average directivity diagram of type III bursts in two dimensions, longitude and latitude relative to the emission source. This diagram is found to exhibit no significant variation with the solar activity. The diagram in longitude is found to shift east of the local magnetic field direction at the source. The angular width and eastward shift of the diagram are observed to increase with decreasing frequencies; around 800 kHz, its full width at maximum/10 level is about 190• and its eastward shift 23• . The diagram in latitude, obtained uniquely thanks to the out-of-ecliptic orbit of Ulysses, shows no significant variation with latitude.

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“…With an average e-folding angle of the electron intensity of 23 ~ (Schellert, Wibberenz, and we get only a small contribution to the intensity variations from the angular spread. The broad scatter in the type III-electron correlation can be understood partly due to event-to-event variations in the energy spectra and angular distributions of the radio emission generating electrons ) and due to the emission/propagation mechanism of the electromagnetic radiation (Fitzenreiter, Evans, and Lin, 1976;Dulk et al, 1985;cf. Hucke, 1990).…”

Section: Discussionmentioning

confidence: 99%

Interplanetary type III radiobursts and relativistic electrons

1992

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For the time periods 1979 April 22-May 17 and 1980 May 9-June 10, when the HELIOS spacecraft were located inside 0.5 AU, we compared the antenna temperature TA of the 466 kHz type III bursts measured by the SBH instrument on ISEE 3 with the fluxes of ~ 0.5 MeV electrons measured by HELIOS. For 51 flare-associated kilometric type III bursts (FAIII bursts) with 1og(TA)> 10 we find:(1) 25 bursts (49 % ) are accompanied by a relativistic electron event in interplanetary space, (2) the probability for detection of an electron event decreases from more than 74 % inside a cone of + 20 o to 56 % inside a cone of + 60 ~ around the flare site, (3) there is only a small correlation between the brightness temperature of the radio burst and the size of the electron event, and (4) despite the broad scatter of these values there is a clear indication that for a given size of the relativistic electron event the intensity of the type III burst is about a factor of 5 higher if it is accompanied by a type II burst. These results give evidence (a) that at least part of the relativistic electrons frequently is accelerated together with non-relativistic electrons and (b) that the coronal shock associated with the metric type II burst has a weaker effect on relativistic than on non-relativistic electrons.

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Latitude Distribution of Interplanetary Magnetic Field Lines Rooted in Active Regions

Cited by 31 publications

References 2 publications

Open magnetic flux tubes in the corona and the transport of solar energetic particles

Open magnetic flux tubes in the corona and the transport of solar energetic particles

The directivity of solar type III bursts at hectometer and kilometer wavelengths: Wind-Ulysses observations

Interplanetary type III radiobursts and relativistic electrons

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