ESASky SSOSS: Solar System Object Search Service and the case of Psyche

TL;DR

The paper introduces SSOSS, a service for identifying potential detections of Solar System objects in ESA archival data, and demonstrates its use by analyzing the asteroid Psyche's thermal properties using Herschel data.

Contribution

It presents a new search service for SSOs in ESA archives and applies it to derive thermal properties of asteroid Psyche from serendipitous Herschel detections.

Findings

909 serendipitous Herschel detections of SSOs

Strong evidence for emissivity drop from 100 to 350 μm

Psyche's thermal inertia constrained between 20-80 J m^{-2} s^{-1/2} K^{-1}

Abstract

We introduce in this work the Solar System Object Search Service (SSOSS), a service aimed at providing the scientific community with a search service for all potential detections of SSOs among the ESA astronomy archival imaging data. We illustrate its functionalities using the case of asteroid (16) Psyche, for which no information in the far-IR (70-500 {\mu}m) has previously been reported, to derive its thermal properties in preparation for the upcoming NASA Psyche mission. This service performs a geometrical cross-match of the orbital path of each object with respect to the public high-level imaging footprints stored in the ESA archives. For this first release, three missions were chosen: XMM-Newton, the Hubble Space Telescope (HST), and Herschel Observatory. We present a catalog listing all potential detections of asteroids within estimated limiting magnitude or flux limit in Herschel, XMM-Newton, and HST archival imaging data, including 909 serendipitous detections in Herschel images, 985 in XMM-Newton Optical Monitor camera images, and over 32,000 potential serendipitous detections in HST images. We also present a case study: the analysis of the thermal properties of Psyche from four serendipitous Herschel detections, combined with previously published thermal IR measurements. We see strong evidence for an unusual drop in (hemispherical spectral) emissivity, from 0.9 at 100 {\mu}m down to about 0.6 at 350 {\mu}m, followed by a possible but not well-constrained increase towards 500 {\mu}m, comparable to what was found for Vesta. The combined thermal data set puts a strong constraint on Psyche's thermal inertia (between 20 to 80$J m^{-2} s^{-1/2} K^{-1}$) and favours an intermediate to low level surface roughness (below 0.4 for the rms of surface slopes).