Solar radio burst and in situ determination of interplanetary electron density

Bougeret, Jean‐Louis; King, J. H.; Schwenn, R.

doi:10.1007/bf00173965

Cited by 77 publications

(45 citation statements)

References 20 publications

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“…4 shows that this is the case for the daily averages of density measured by Helios 1 during 1975. A linear least squares ÿt to the data, which are plotted on a log-log scale, gives N˙R −(2:1±0:1) , which is consistent with Bougeret et al (1984). The R −2 dependence of the momentum ux is a consequence of the radial variation of the density, since V is approximately independent of R. Fig.…”

Section: Radial Variationssupporting

confidence: 77%

Magnetic fields and plasmas in the inner heliosphere: Helios results

Burlaga

2001

Planetary and Space Science

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The magnetic ÿeld of Mercury and the structure and dynamics of Mercury's magnetosphere, which will be studied by the spacecraft orbiting Mercury, are strongly in uenced by the interaction of the solar wind with Mercury. In order to understand the internal magnetic ÿeld, it will be necessary to correct the observations of the external ÿeld for the distortions produced by the solar wind. Understanding of the solar wind interaction with Mercury is essential for understanding the structure and dynamics of the magnetosphere and phenomena such as magnetic storms. Helios 1 and 2 made a number of passes in the region traversed by the orbit of Mercury, and each pass provided a sample of the solar wind environment of Mercury. This paper reviews the plasma and magnetic ÿeld observations from Helios that provide a general basis for interpreting the observations of Mercury that will be made by orbiting spacecraft. The variables that govern the structure and dynamics of the magnetospheres of Mercury and Earth are approximately 5 -10 times larger at Mercury than at Earth. Thus, the solar wind interaction with Mercury will be much stronger than the interaction with Earth. Moreover, the solar wind at Mercury is probably more variable than that at Earth. There is a clear need for measurements of the solar wind during the approach of spacecraft to Mercury and while they are in orbit around Mercury.

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Section: Radial Variationssupporting

confidence: 77%

Magnetic fields and plasmas in the inner heliosphere: Helios results

Burlaga

2001

Planetary and Space Science

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“…The Helios missions, (Rosenbauer et al 1977) extended the in situ measurements down to r ≈ 0.3 a.u. ≈ 65 r (Bougeret et al 1984a). However, the inner parts of IP space can be investigated only indirectly, e.g., utilizing measurements in the radio-range (e.g., Bougeret et al 1984aBougeret et al , 1984bLeblanc et al 1998, and references therein).…”

Section: Introductionmentioning

confidence: 95%

Band-splitting of coronal and interplanetary type II bursts

Vršnak

Magdalenić

Zlobec

2003

A&A

143

105

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Abstract. We analyse properties of 58 type II radio bursts recorded in the meter-to-kilometer wavelength range, focusing on episodes of band-split emission. The basic two parameters utilized are the frequency drift D f = d f /dt and the relative band-split BDW = ∆ f / f of type II burst emission lanes. On average, in the meter-to-kilometer wavelength range D f increases with the emission frequency as D f ∝ f 1.83 , revealing that source velocities are smaller at larger heliocentric distances. The relative bandsplit shows a weak but statistically significant dependence on the emission frequency, BDW ∝ f −0.06 , indicating an increase of BDW with the heliocentric distance. Combining the shock velocity estimated from the frequency drift, with the Mach number inferred from the band-split, the Alfvén speed and the magnetic field in the ambient plasma can be estimated as a function of the heliocentric distance r. However, the outcome directly depends on the coronal/interplanetary density model used, which is poorly known in the upper corona and the near-Sun interplanetary space. So, we invert the problem: utilizing the results of the previous paper where it was shown that beyond the heliocentric distance of two solar radii (r/r = R > 2) the average magnetic field decreases approximately as B ∝ R −2 , we infer the density n(R) in the upper corona and near-Sun interplanetary space. The obtained empirical dependence n(R) is presented in the analytical form as a four-degree polynomial of 1/R, and is compared with some theoretical n(R) models, considering also a deviation from the B ∝ 1/R 2 scaling used. The model matches the five-fold Saito density model (representing the active region corona) with the n ∝ R −2 regime in the interplanetary space. Furthermore, it is shown that on average the magnetosonic speed attains a local minimum of v ms ≈ 400 km s −1 around R = 3 and a broad local maximum of v ms ≈ 500 km s −1 in the range R = 4−6, beyond which it gradually decreases to several tens km s −1 at 1 a.u. The local minimum becomes even deeper if the super-radial expansion of the magnetic field is taken into account. The implications regarding the formation and evolution of shocks in the corona and upper corona are discussed in the framework of CME-piston and flare-blast scenarios. The inferred general decrease of type II burst source velocities and broadening of band-splits with distance is interpreted in terms of the deceleration of mass ejections driving the shocks in the decreasing v ms environment.

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“…Table 3 represents the estimated electron densities at 20 R and 215 R (1 AU) from the various models. These models are representative of radio science measurements (Muhleman et al 1977;Anderson et al 1987;Bird et al 1994Bird et al , 1996, in situ measurements (Bougeret et al 1984;Issautier et al 1997), and Table 2. The error bars plotted in the figure correspond to the electron density obtained at 20 R and 215 R (see Table 2).…”

Section: Venus Superior Conjunctionmentioning

confidence: 81%

Electron density distribution and solar plasma correction of radio signals using MGS, MEX, and VEX spacecraft navigation data and its application to planetary ephemerides

Verma

Fienga

Laskar

et al. 2013

A&A

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The Mars Global Surveyor (MGS), Mars Express (MEX), and Venus Express (VEX) experienced several superior solar conjunctions. These conjunctions cause severe degradations of radio signals when the line of sight between the Earth and the spacecraft passes near to the solar corona region. The primary objective of this work is to deduce a solar corona model from the spacecraft navigation data acquired at the time of solar conjunctions and to estimate its average electron density. The corrected or improved data are then used to fit the dynamical modeling of the planet motions, called planetary ephemerides. We analyzed the radio science raw data of the MGS spacecraft using the orbit determination software GINS. The range bias, obtained from GINS and provided by ESA for MEX and VEX, are then used to derive the electron density profile. These profiles are obtained for different intervals of solar distances: from 12 R to 215 R for MGS, 6 R to 152 R for MEX, and from 12 R to 154 R for VEX. They are acquired for each spacecraft individually, for ingress and egress phases separately and both phases together, for different types of solar winds (fast, slow), and for solar activity phases (minimum, maximum). We compared our results with the previous estimations that were based on in situ measurements, and on solar type III radio and radio science studies made at different phases of solar activity and at different solar wind states. Our results are consistent with estimations obtained by these different methods. Moreover, fitting the planetary ephemerides including complementary data that were corrected for the solar corona perturbations, noticeably improves the extrapolation capability of the planetary ephemerides and the estimation of the asteroids masses.

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Solar radio burst and in situ determination of interplanetary electron density

Cited by 77 publications

References 20 publications

Magnetic fields and plasmas in the inner heliosphere: Helios results

Magnetic fields and plasmas in the inner heliosphere: Helios results

Band-splitting of coronal and interplanetary type II bursts

Electron density distribution and solar plasma correction of radio signals using MGS, MEX, and VEX spacecraft navigation data and its application to planetary ephemerides

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