Hydromagnetic Steady Magnetized Plasma Encountered by Voyager in the Interstellar Space

Abstract

With the spacecraft Voyager 1 and 2, we observe from the inside the near interstellar medium that is a very strongly magnetized (|B| equal or larger than 0.4 nT) medium, which is very dilute. We deal with a medium about 8-orders of magnitude less dense than the best vacuum possible to achieve in the laboratory. For the considered matter densities the plasma energy is quite small at a random equivalent thermal value of no more than 30,000°K, so that a B-field of 1/2 nT constitutes a very strong magnetic field. Consequently, the medium’s pressure is dominated by the B-field. Based on these everyday measurements, we proceed to interpret the nature of the medium, assuming the reasonable, consistent result, we check with observation that its overall property satisfies hydromagnetism (MHD). The intensity of the B-field is consistent with remote sensing of the 21 cm split of the e-line of the atomic Hydrogen, and permits to understand the ancient nature of the medium, for example, constituting an example of permanent magnetism, and in this way we infer a few possibilities on the nature of the whole structure of the surrounding local interstellar magnetic cloud and the evolution of the home galaxy.