Exoplanetary atmosphere target selection in the era of comparative planetology

TL;DR

This paper introduces a decision metric for selecting optimal exoplanet targets for atmospheric transmission spectroscopy, enabling efficient use of diverse telescopes and improving population studies without extensive prior data.

Contribution

It proposes a novel, easily deployable decision metric for target and telescope selection, enhancing follow-up strategies in exoplanet atmospheric studies.

Findings

Effective target ranking correlates with successful atmospheric detections.

The metric optimizes telescope and filter choices for transmission spectroscopy.

It enables statistical evaluation of dataset completeness.

Abstract

The large number of new planets expected from wide-area transit surveys means that follow-up transmission spectroscopy studies of their atmospheres will be limited by the availability of telescope assets. We argue that telescopes covering a broad range of apertures will be required, with even 1m-class instruments providing a potentially important contribution. Survey strategies that employ automated target selection will enable robust population studies. As part of such a strategy, we propose a decision metric to pair the best target to the most suitable telescope, and demonstrate its effectiveness even when only primary transit observables are available. Transmission spectroscopy target selection need not therefore be impeded by the bottle-neck of requiring prior follow-up observations to determine the planet mass. The decision metric can be easily deployed within a distributed heterogeneous network of telescopes equipped to undertake either broadband photometry or spectroscopy. We show how the metric can be used either to optimise the observing strategy for a given telescope (e.g. choice of filter) or to enable the selection of the best telescope to optimise the overall sample size. Our decision metric can also provide the basis for a selection function to help evaluate the statistical completeness of follow-up transmission spectroscopy datasets. Finally, we validate our metric by comparing its ranked set of targets against lists of planets that have had their atmospheres successfully probed, and against some existing prioritised exoplanet lists.