Search for signatures of dust in the Pluto-Charon system using Herschel/PACS observations

TL;DR

This study used Herschel/PACS far-infrared observations to search for dust signatures around Pluto-Charon, finding no evidence of a dust ring and setting upper limits on possible dust mass and density.

Contribution

First to analyze Herschel/PACS data for dust signatures in the Pluto-Charon system, establishing detection limits and assessing impact hazards for New Horizons.

Findings

No extended dust ring detected around Pluto-Charon.

Set upper limits on dust mass and column density.

Predicted minimal hazard during New Horizons flyby.

Abstract

In this letter we explore the environment of Pluto and Charon in the far infrared with the main aim to identify the signs of any possible dust ring, should it exist in the system. Our study is based on observations performed at 70 um with the PACS instrument onboard the Herschel Space Observatory at 9 epochs between March 14 and 19, 2012. The far-infrared images of the Pluto-Charon system are compared to those of the point spread function (PSF) reference quasar 3C454.3. The deviation between the observed Pluto-Charon and reference PSFs are less then 1 sigma indicating that clear evidence for an extended dust ring around the system was not found. Our method is capable of detecting a hypothetical ring with a total flux of ~3.3 mJy at a distance of ~153 000 km (~8.2 Pluto-Charon distances) from the system barycentre. We place upper limits on the total disk mass and on the column density in a reasonable disk configuration and analyse the hazard during the flyby of NASAs New Horizons in July 2015. This realistic model configuration predicts a column density of 8.7x10^(-10) gcm^(-2) along the path of the probe and an impactor mass of 8.7x10^(-5) g.