Probing the Large Scale Plasma Structure of the Solar Corona with Faraday Rotation Measurements

Abstract

Faraday rotation measurements of the solar corona made with the Very Large Array (VLA) at frequencies of 1465 and 1665 MHz are reported. The measurements were made along 20 lines of sight to 19 extragalactic radio sources in March and April, 2005. The closest heliocentric distances of the lines of sight ranged from 9.7 to 5.6 $R_{\odot }$. Measured rotation measures range from -25 to +61 rad/m${}^2$. The purpose of these observations is to probe the three dimensional structure of the coronal plasma in the heliocentric distance range $5-10R_{\odot }$, and particularly the strength and structure of the coronal magnetic field. The measured rotation measures are compared with models for the coronal plasma structure. For the majority of the lines of sight, the observed rotation measures are reasonably well represented by the predictions from the models. However, 4 of the 20 lines of sight have large observed-model residuals, which do not seem associated with coronal mass ejections. The magnitude of the field necessary to reproduce the majority of the observations is in the range 46-120 milliGauss at $5R_{\odot }$, with a smaller, preferred range of 46-52 mG at $5R_{\odot }$.

32 pages, 7 figures

References in corpus (1)

• Assessing the tilt of the solar magnetic field axis through Faraday rotation observations

Cited by in corpus (9)

• The challenges of low-frequency radio polarimetry: lessons from the Murchison Widefield Array
• A Technique for Measuring Electrical Currents in the Solar Corona
• Solar Coronal Magnetic Fields and Sensitivity Requirements for Spectropolarimetry Channel of VELC Onboard Aditya-L1
• Occultations of astrophysical radio sources as probes of planetary environments: A case study of Jupiter and possible applications to exoplanets
• Inferences About the Magnetic Field Structure of a CME with Both In Situ and Faraday Rotation Constraints
• Radio Remote Sensing of the Corona and the Solar Wind
• Plasma properties from the multi-wavelength analysis of the November 1st 2003 CME/shock event
• Radio Burst and Circular Polarization Studies of the Solar Corona at Low Frequencies
• Enhancing MHD model accuracy and CME forecasting by constraining coronal plasma properties with Faraday rotation