# A circumbinary protoplanetary disc in a polar configuration

## TL;DR

This paper reports the first discovery of a polar configuration in a circumbinary protoplanetary disc, confirming theoretical predictions and indicating that planet formation can occur in such misaligned systems.

## Contribution

The discovery of a polar circumbinary disc supports theoretical models predicting such configurations and shows planet formation processes can occur in these misaligned discs.

## Key findings

- First observed polar circumbinary disc
- Disc shows dust growth similar to single-star discs
- Planet formation likely proceeds in polar configurations

## Abstract

Nearly all young stars are initially surrounded by `protoplanetary' discs of gas and dust, and in the case of single stars at least 30\% of these discs go on to form planets. The process of protoplanetary disc formation can result in initial misalignments, where the disc orbital plane is different to the stellar equator in single star systems, or to the binary orbital plane in systems with two stars. A quirk of the dynamics means that initially misaligned `circumbinary' discs -- those that surround two stars -- are predicted to evolve to one of two possible stable configurations, one where the disc and binary orbital planes are coplanar, and one where they are perpendicular (a `polar' configuration). Prior work has found coplanar circumbinary discs, but no polar examples were known until now. Here we report the first discovery of a protoplanetary circumbinary disc in the polar configuration, supporting the predictions that such discs should exist. The disc shows some characteristics that are similar to discs around single stars, and that are attributed to dust growth. Thus, the first stages of planet formation appear able to proceed in polar circumbinary discs.