Abstract
Depressions in magnetic field strength, commonly referred to as magnetic
holes, are observed ubiquitously in space plasmas. Sub-proton-scale
magnetic holes with spatial scales smaller than or on the order of
$\rho_p$, are likely supported by electron currents
vortices, rotating perpendicular to the ambient magnetic field. While
there are numerous accounts of sub-proton-scale magnetic holes within
the Earth’s magnetosphere, there are no reported observations in other
space plasma environments. We present the first evidence of
sub-proton-scale magnetic holes in the Venusian magnetosheath. During
Parker Solar Probe’s first Venus Gravity Assist, the spacecraft crossed
the planet’s bow shock and subsequently observed the Venusian
magnetosheath. The FIELDS instrument suite onboard the spacecraft
achieved magnetic and electric field measurements of magnetic hole
structures. The electric field associated with magnetic depressions are
consistent with electron current vortices with amplitudes on the order
of 1 $\mu$A/m$^2$.