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Published March 10, 2026 | Version Published
Journal Article Open

Estimating Electron Densities in the Middle Solar Corona Using White-light and Radio Observations

Creators

  • 1. ROR icon New Jersey Institute of Technology
  • 2. ROR icon George Mason University
  • 3. ROR icon United States Naval Research Laboratory
  • 4. ROR icon Johns Hopkins University Applied Physics Laboratory
  • 5. Cooperative Programs for the Advancement of Earth System Science, University Corporation for Atmospheric Research, Boulder, CO, USA
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Jet Propulsion Lab
  • 8. ROR icon Arizona State University
  • 9. ROR icon University of New Mexico
  • 10. Real-Time Radio Systems Ltd, Bournemouth, Dorset BH 6 3LU, UK
  • 11. ROR icon Rice University

Abstract

The electron density of the solar corona is a fundamental parameter in many areas of solar physics. Traditionally, routine estimates of coronal density have relied exclusively on white-light observations. However, these density estimates, obtained by inverting the white-light data, require simplifying assumptions, which may affect the robustness of the measurements. Hence, to improve the reliability of coronal density measurements, it is highly desirable to explore other complementary methods. In this study, we estimate the coronal electron densities in the middle corona, between approximately 1.7 and 3.5 R⊙, using low-frequency radio observations from the recently commissioned Long Wavelength Array at the Owens Valley Radio Observatory (OVRO-LWA). The results demonstrate consistency with those derived from white-light coronagraph data and predictions from theoretical models. We also derive a density model valid between 1.7 and 3.5 r⊙, given by ρ(r′) = 1.27 r′⁻² + 29.02 r′⁻⁴ + 71.18 r′⁻⁶, where r′ = r/R⊙, with r the heliocentric distance. OVRO-LWA is a solar-dedicated radio interferometer that provides science-ready images with low latency, making it well suited for generating regular and independent estimates of coronal densities to complement existing white-light techniques.

Copyright and License

© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

The OVRO-LWA expansion project was supported by NSF under grant AST-1828784. OVRO-LWA operations for solar and space weather sciences are supported by NSF under grant AGS-2436999. SOHO is a joint mission of the European Space Agency (ESA) and the US National Aeronautics and Space Administration (NASA). LASCO was built by a consortium of the Naval Research Laboratory, USA; the Laboratoire d’Astronomie Spatiale in Marseille, France; the Max Planck Institute für Aeronomie in Lindau, Germany; and the School of Physics and Astronomy, the University of Birmingham, UK. S.S. and R.H. thank K. Battams, the principal investigator of LASCO, for all the valuable discussions on the LASCO/C2 calibration. P.Z. acknowledges support for this research by the NASA Living with a Star Jack Eddy Postdoctoral Fellowship Program, administered by UCAR’s Cooperative Programs for the Advancement of Earth System Science (CPAESS) under award 80NSSC22M0097. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2602.09819 (arXiv)

Funding

National Science Foundation
AST-1828784
National Science Foundation
AGS-2436999
National Aeronautics and Space Administration
80NSSC22M0097
National Aeronautics and Space Administration
80NM0018D0004

Dates

Submitted
2025-09-17
Accepted
2026-02-05
Available
2026-03-06
Published

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Caltech groups
Owens Valley Radio Observatory , Astronomy Department , Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published