Interstellar Comets from Post-Main Sequence Systems as Tracers of Extrasolar Oort Clouds

TL;DR

This paper evaluates the potential for the LSST to detect interstellar exo-comets called Jurads, formed during post-main sequence stellar evolution, and assesses their distinguishability from other interstellar objects.

Contribution

It provides analytic and numerical estimates of Jurad ejection rates, surface alterations, and models the interstellar small body reservoir to evaluate detection prospects.

Findings

Detection of a Jurad with LSST is unlikely but possible.

Stellar winds may deposit dust covering Jurads' surfaces.

Post-main sequence ejection contributes to interstellar small bodies.

Abstract

Interstellar small bodies are unique probes into the histories of exoplanetary systems. One hypothesized class of interlopers are "Jurads," exo-comets released into the Milky Way during the post-main sequence as the thermally-pulsing asymptotic giant branch (AGB) host stars lose mass. In this study, we assess the prospects for the Legacy Survey of Space and Time (LSST) to detect a Jurad and examine whether such an interloper would be observationally distinguishable from exo-comets ejected during the (pre-)main sequence. Using analytic and numerical methods, we estimate the fraction of exo-Oort Cloud objects that are released from 1-8 solar mass stars during post-main sequence evolution. We quantify the extent to which small bodies are altered by the increased luminosity and stellar outflows during the AGB, finding that some Jurads may lack hypervolatiles and that stellar winds could deposit dust that covers the entire exo-comet surface. Next, we construct models of the interstellar small body reservoir for various size-frequency distribution slopes, characteristic sizes, and the total mass sequestered in the minor planets of exo-Oort Clouds. Even with the LSST's increased search volume compared to contemporary surveys, we find that detecting a Jurad is unlikely but not infeasible given the current understanding of (exo)planet formation.