The electron density profile of the outer corona and the interplanetary medium from Mariner-6 and Mariner-7 time-delay measurements

Abstract

view Abstract Citations (37) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The electron density profile of the outer corona and the interplanetary medium from Mariner-6 and Mariner-7 time-delay measurements. Muhleman, D. O. ; Esposito, P. B. ; Anderson, J. D. Abstract The round-trip propagation time delays to the Mariner-6 and Mariner-7 spacecraft were measured over a 6 month period, including the occultations by the solar corona during April and May of 1970. The interplanetary medium was sampled over a range of ray impact parameters from about 5 to 100 solar radii. Electron density models fitted to the observations show that the density profile falls off nearly exactly as the inverse square of the distance from about 10 solar radii out to the Earth's orbit. The estimated values of the slopes are -2.05 and -2.08 for Mariner-6 and Mariner- 7, respectively. The formal standard deviation on each estimate is +0.24. In general, the densities are about a factor of 2 smaller than those determined by eclipse photometric measurements. The latter result agrees with recent radio ray-bending and pulsar timedelay measurements. The fluctuations in the measured time delays show that the true standard deviation of the electron density at a given point is about 100% of the local mean density. The evaluations of the estimated electron density profiles at 1 AU yield 9 + 3 electrons cm -3 for both spacecraft experiments, which were analyzed independently. Our results are strictly correct only if the general-relativistic effects are those predicted by Einstein's general theory. Subject headings: interplanetary medium - Sun: corona Publication: The Astrophysical Journal Pub Date: February 1977 DOI: 10.1086/155006 Bibcode: 1977ApJ...211..943M Keywords: Electron Density Profiles; Interplanetary Medium; Mariner Space Probes; Solar Corona; Time Lag; Mariner 6 Space Probe; Mariner 7 Space Probe; Mathematical Models; Occultation; Power Spectra; Pulsars; Solar Electrons; Solar Gravitation; Astrophysics full text sources ADS |