Solar Corona Electron Densities from VLBI and GIM Data

Soja, Benedikt; Heinkelmann, Robert; Schuh, Harald

doi:10.1007/1345_2015_155

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…It was concluded that the approach using only VLBI data leads to more reliable and precise results. It has to be noted that in this publication 26 , the assumption of β =2.3 leads to different numerical values for N 0 compared to what is shown in Table 3 . This assumption has a negligible effect on the electron density at the heliospheric distances at which the VLBI data were recorded.…”

Section: Resultsmentioning

confidence: 74%

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Probing the solar corona with very long baseline interferometry

2014

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Understanding and monitoring the solar corona and solar wind is important for many applications like telecommunications or geomagnetic studies. Coronal electron density models have been derived by various techniques over the last 45 years, principally by analysing the effect of the corona on spacecraft tracking. Here we show that recent observational data from very long baseline interferometry (VLBI), a radio technique crucial for astrophysics and geodesy, could be used to develop electron density models of the Sun’s corona. The VLBI results agree well with previous models from spacecraft measurements. They also show that the simple spherical electron density model is violated by regional density variations and that on average the electron density in active regions is about three times that of low-density regions. Unlike spacecraft tracking, a VLBI campaign would be possible on a regular basis and would provide highly resolved spatial–temporal samplings over a complete solar cycle.

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Section: Resultsmentioning

confidence: 74%

“…Soja et al 26 performed comparisons with external ionospheric data from GPS to test the approach of estimating the parameters of the ionosphere from VLBI data. In general, a good agreement between the vertical TEC obtained from the two techniques was found, with maximum differences close to the stated accuracy of the GPS data.…”

Section: Resultsmentioning

confidence: 99%

Probing the solar corona with very long baseline interferometry

2014

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Testing general relativity with geodetic VLBI

Titov

Girdiuk

Lambert

et al. 2018

A&A

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The geodetic VLBI technique is capable of measuring the Sun's gravity light deflection from distant radio sources around the whole sky. This light deflection is equivalent to the conventional gravitational delay used for the reduction of geodetic VLBI data. While numerous tests based on a global set of VLBI data have shown that the parameter γ of the post-Newtonian approximation is equal to unity with a precision of about 0.02 percent, more detailed analysis reveals some systematic deviations depending on the angular elongation from the Sun. In this paper a limited set of VLBI observations near the Sun were adjusted to obtain the estimate of the parameter gamma free of the elongation angle impact. The parameter γ is still found to be close to unity with precision of 0.06 percent, two subsets of VLBI data measured at short and long baselines produce some statistical inconsistency.

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Exploring the Asymmetry of the Solar Corona Electron Density with Very Long Baseline Interferometry

Aksim

Melnikov

Pavlov

et al. 2019

ApJ

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The Sun's corona has interested researchers for multiple reasons, including the search for solution for the famous coronal heating problem and a purely practical consideration of predicting geomagnetic storms on Earth. There exist numerous different theories regarding the solar corona; therefore, it is important to be able to perform comparative analysis and validation of those theories. One way that could help us move towards the answers to those problems is the search for observational methods that could obtain information about the physical properties of the solar corona and provide means for comparing different solar corona models.In this work we present evidence that VLBI observations are, in certain conditions, sensitive to the electron density of the solar corona and are able to distinguish between different electron density models, which makes the technique of VLBI valuable for solar corona investigations. Recent works on the subject used a symmetric power-law model of the electron density in solar plasma; in this work, an improvement is proposed based on a 3D numerical model.

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Solar Corona Electron Densities from VLBI and GIM Data

Cited by 3 publications

References 11 publications

Probing the solar corona with very long baseline interferometry

Probing the solar corona with very long baseline interferometry

Testing general relativity with geodetic VLBI

Exploring the Asymmetry of the Solar Corona Electron Density with Very Long Baseline Interferometry

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