Haze at Occator crater on dwarf planet Ceres

TL;DR

This study investigates a diurnal haze at Occator crater on Ceres, using imaging data to analyze light scattering and support the presence of a tenuous exosphere, aligning with water vapor detections.

Contribution

It provides detailed analysis of the haze phenomenon at Occator, suggesting the presence of a haze layer affecting light scattering, which supports the existence of a cerean exosphere.

Findings

Haze layer causes unusual light scattering at Occator's floor.

Surface scattering behavior deviates from typical cerean surface.

Results support water vapor presence detected by Herschel.

Abstract

A diurnal varying haze layer at the bright spots of Occator on dwarf planet Ceres has been reported from images of the Dawn Framing Camera. This finding is supported by ground-based observations revealing diurnal albedo changes at Occator's longitude. In the present work, we further investigate the previously reported haze phenomenon in more detail using additional Framing Camera images. We demonstrate that the light scattering behavior at the central floor of Occator is different compared to a typical cerean surface and is likely inconsistent with a pure solid surface scatterer. The identified deviation is best explained by an additional component to the scattered light of the surface, i.e., a haze layer. Our results support the water vapor detection by Herschel observations though the existence of a tenuous cerean exosphere is not yet confirmed.