Seeing Double at Neptune's South Pole

TL;DR

This study uses near-infrared imaging to observe a transient split in Neptune's south polar cloud features, indicating dynamic atmospheric processes possibly linked to a south polar vortex.

Contribution

First detailed near-infrared imaging of Neptune's south polar clouds showing a temporary split into two bright spots, revealing atmospheric dynamics.

Findings

Cloud features split into two bright spots

Features constrained to the troposphere at >0.4 bar

Single feature observed two days later

Abstract

Keck near-infrared images of Neptune from UT 26 July 2007 show that the cloud feature typically observed within a few degrees of Neptune's south pole had split into a pair of bright spots. A careful determination of disk center places the cloud centers at -89.07 +/- 0 .06 and -87.84 +/- 0.06 degrees planetocentric latitude. If modeled as optically thick, perfectly reflecting layers, we find the pair of features to be constrained to the troposphere, at pressures greater than 0.4 bar. By UT 28 July 2007, images with comparable resolution reveal only a single feature near the south pole. The changing morphology of these circumpolar clouds suggests they may form in a region of strong convection surrounding a Neptunian south polar vortex.