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Accepted manuscript

Probing interplanetary scintillation using broadband VLBI

Published online by Cambridge University Press:  16 April 2025

A. Jaradat*
Affiliation:
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, 7005, Tasmania, Australia
G. Molera Calvés
Affiliation:
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, 7005, Tasmania, Australia
J. Edwards
Affiliation:
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, 7005, Tasmania, Australia CSIRO Space and Astronomy, Epping, 1710, NSW, Australia.
S. Ellingsen
Affiliation:
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, 7005, Tasmania, Australia International Centre for Radio Astronomy Research, The University of Western Australia, Crawley, 6009, WA, Australia.
T. McCarthy
Affiliation:
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, 7005, Tasmania, Australia
J. Morgan
Affiliation:
CSIRO Space and Astronomy, Bentley, 6102, WA, Australia
*
Author for correspondence: A. Jaradat, Email: [email protected].
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Abstract

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Advancements in VLBI instrumentation, driven by the geodetic community’s goal of achieving positioning accuracy of 1 mm and stability of 0.1 mm/y, have led to the development of new broadband systems. Here, we assess the potential of these new capabilities for space weather monitoring. These enhanced VLBI capabilities were used to investigate interplanetary scintillation (IPS), a phenomenon caused by the scattering of radio waves due to density irregularities in the solar wind. Compact radio sources near the Sun were observed using the AuScope VLBI array in Australia, which consists of 12-meter telescopes at Hobart, Katherine, and Yarragadee. The baseline lengths between these telescopes are approximately 3400 km (Hobart–Katherine), 3200 km (Hobart–Yarragadee), and 2400 km (Katherine–Yarragadee). The observations covered solar elongations from 6.5° to 11.3° and frequencies between 3 and 13 GHz. The study focused on phase scintillation as an indicator of turbulence in the solar wind. As the solar elongation decreased, we observed an increase in the phase scintillation index, consistent with theoretical models. Importantly, the broadband system also detected IPS using relatively weak radio sources. Additionally, the phase scintillation increased with baseline length, in agreement with Kolmogorov turbulence with an index of 11/3. These findings demonstrate the effectiveness of geodetic broadband VLBI in capturing detailed features of the solar wind. This capability enables continuous space weather monitoring and advances our understanding of solar and interplanetary dynamics.

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Astronomical Society of Australia