A shift in Jupiter's equatorial haze distribution imaged with the Multi-Conjugate Adaptive Optics Demonstrator at the VLT

TL;DR

This study used advanced adaptive optics imaging to observe Jupiter's equatorial haze, revealing significant distribution changes potentially linked to atmospheric dynamics and cloud activity.

Contribution

First high-resolution adaptive optics images of Jupiter's equatorial haze showing a shift in distribution and insights into haze formation and transport mechanisms.

Findings

Haze distribution shifted from 5°N to the equator since 2005.

Haze reflectivity varies with particle size and cloud source changes.

Haze variation is influenced by particle size, cloud sources, diffusion, and transport.

Abstract

Jupiter was imaged during the Science Demonstration of the MCAO Demonstrator (MAD) at the European Southern Observatory's UT3 Very Large Telescope unit. Io and Europa were used as natural guide stars on either side of Jupiter, separated from each other by about 1.6 arcmin from 23:41 to 01:32 UT (2008 Aug 16/17). The corrected angular resolution was 0.090 arcsec across the entire field of view, as measured on background stars. The observations at 2.02, 2.14, and 2.16 micrometers were sensitive to portions of the Jovian spectrum with strong methane absorption. The data probe the upper troposphere, which is populated with a fine (~0.5 micrometer) haze. Two haze sources have been proposed: lofting of fine cloud particles into the stable upper troposphere, and condensation of hydrazine produced via ammonia photochemistry. The upper tropospheric haze is enhanced over Jupiter's equatorial region. Dramatic changes in the underlying cloud cover--part of the 2006/2007 "global upheaval"--may be associated with changes in the equatorial haze distribution now evident in the 2008 MAD images. Haze reflectivity peaked at 5 degrees N in HST/NICMOS data from 2005, but it now peaks at the equator. The observations suggest that haze variation is controlled by particle size, cloud source variation, diffusion, and horizontal transport.