[Paper Review] JIRAM Observations of Volcanic Flux on Io: Distribution and Comparison to Tidal Heat Flow Models

Maurizio Pettine, S. Imbeah+7 more|arXiv (Cornell University)|Aug 10, 2023

Astro and Planetary SciencePhysics and Astronomy3 citations

TL;DR

This study uses infrared data from Juno's JIRAM instrument to create a high-resolution global map of volcanic heat flux on Io, revealing distinct spatial patterns in volcanic activity. It finds that both poles are comparably active and that the observed flux distribution contradicts asthenospheric heating models, supporting tidal heating as the dominant energy source.

ABSTRACT

Juno has allowed clear, high-resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M-band (4.78 um) imager from eleven Juno orbits to construct a global map of volcanic flux. This map provides short-term insight into the spatial distribution of volcanoes and the ways in which high- and low-latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer et al. 2019). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends.

Motivation & Objective

• To map the spatial distribution of volcanic heat flux on Io using high-resolution infrared data from the Juno mission.
• To compare observed volcanic flux patterns with theoretical models of tidal heat deposition in Io's interior.
• To assess whether the observed flux distribution supports or contradicts asthenospheric heating models.
• To evaluate the relative activity levels at Io's high- and low-latitude volcanic regions.

Proposed method

• Acquisition of M-band (4.78 µm) infrared imaging data from 11 Juno flybys using the Jovian Infrared Auroral Mapper (JIRAM) instrument.
• Construction of a global volcanic flux map based on thermal emission measurements from active volcanic features.
• Application of spherical harmonic analysis to compare the observed flux distribution with predicted tidal heat flow models from de Kleer et al. (2019).
• Use of statistical analysis to assess the consistency between observed volcanic flux and tidal heating predictions, particularly at high latitudes.

Experimental results

Research questions

• RQ1 How is volcanic heat flux distributed across Io’s surface based on JIRAM observations?
• RQ2 Are the high-latitude volcanic systems on Io more active than those at lower latitudes?
• RQ3 Does the observed volcanic flux distribution align with predictions from tidal heating models?
• RQ4 Is the asthenospheric heating model consistent with the observed flux patterns on Io?

Key findings

• Both the northern and southern poles of Io exhibit comparable levels of volcanic activity, with no significant asymmetry detected in the observed flux distribution.
• The observed volcanic flux distribution is inconsistent with the asthenospheric heating model, which predicts a different spatial pattern of heat flow.
• Bright volcanic systems are confirmed at high latitudes, consistent with previous observations but now mapped with higher resolution and global coverage.
• The south pole is observed less frequently, limiting reliable trend analysis, but the available data do not support a dominant role for asthenospheric convection.