Turbulence in the Very Local Interstellar Medium (VLISM)

Abstract

The Voyager 1 spacecraft has been observing interstellar magnetic turbulence since it crossed the heliopause in 2012. Burlaga et al. reported that the turbulence appears to be compressible close to the heliopause and becomes incompressible farther away. In this paper, we undertake a more detailed analysis of the magnetic fluctuations measured by Voyager 1 from 2013 to 2019. We apply the techniques of wavelet analysis and Hilbert spectral analysis. These methods reveal temporal or spatial variations of the fluctuations that are not easily apparent using standard Fourier techniques. Our results suggest that the compressible fluctuations are confined to a smaller region than previously thought.