ALMA Thermal Observations of a Proposed Plume Source Region on Europa

TL;DR

This study uses ALMA thermal imaging and modeling to investigate a potential plume source region on Europa, concluding that surface thermal properties, not excess heat flow, explain observed thermal anomalies.

Contribution

It introduces a global thermal model of Europa that accounts for both daytime and nighttime emissions, challenging the idea of localized excess heat flow as the cause of thermal anomalies.

Findings

Thermal anomalies near Pwyll Crater are explained by increased surface thermal inertia.

Daytime and nighttime brightness temperatures can be modeled without excess heat flow.

Surface properties are key to understanding Europa's thermal emission patterns.

Abstract

We present a daytime thermal image of Europa taken with the Atacama Large Millimeter Array. The imaged region includes the area northwest of Pwyll Crater, which is associated with a nighttime thermal excess seen by the Galileo Photopolarimeter Radiometer and with two potential plume detections. We develop a global thermal model of Europa and simulate both the daytime and nighttime thermal emission to determine if the nighttime thermal anomaly is caused by excess endogenic heat flow, as might be expected from a plume source region. We find that the nighttime and daytime brightness temperatures near Pwyll Crater cannot be matched by including excess heat flow at that location. Rather, we can successfully model both measurements by increasing the local thermal inertia of the surface.