The past, present and future of observations of externally irradiated disks

TL;DR

This paper reviews recent and upcoming observations of externally irradiated protoplanetary disks, emphasizing their role in understanding disk evolution, planet formation, and the influence of ultraviolet radiation from OB stars.

Contribution

It provides a comprehensive overview of current observational efforts and discusses future prospects to study external photoevaporation effects on disks and planet formation.

Findings

Recent observations have advanced understanding of disk photoevaporation.

Upcoming instruments will enable more detailed studies of irradiated disks.

External UV radiation significantly influences protoplanetary disk evolution.

Abstract

Recent years have seen a surge of interest in the community studying the effect of ultraviolet radiation environment, predominantly set by OB stars, on protoplanetary disc evolution and planet formation. This is important because a significant fraction of planetary systems, potentially including our own, formed in close proximity to OB stars. This is a rapidly developing field, with a broad range of observations across many regions recently obtained or recently scheduled. In this paper, stimulated by a series of workshops on the topic, we take stock of the current and upcoming observations. We discuss how the community can build on this recent success with future observations to make progress in answering the big questions of the field, with the broad goal of disentangling how external photoevaporation contributes to shaping the observed (exo)planet population. Both existing and future instruments offer numerous opportunities to make progress towards this goal.