The Number of Transits Per Epoch for Transiting Misaligned Circumbinary Planets

TL;DR

This paper investigates the transit patterns of misaligned circumbinary planets, revealing their unique, non-random sequences and proposing methods to infer their inclination distributions, aiding detection and characterization.

Contribution

It introduces a novel analysis of transit sequences for misaligned circumbinary planets, showing how to infer their inclination distribution and improve detection strategies.

Findings

Misaligned circumbinary planets produce sparse, non-random transit sequences.

Sequences can predict future transits with high accuracy.

Incorrect period assignment can occur due to missing epochs.

Abstract

The growing catalog of circumbinary planets strengthens the notion that planets form in a diverse range of conditions across the cosmos. Transiting circumbinary planets yield especially important insights and many examples are now known, in broadly coplanar obits with respect to their binary. Studies of circumbinary disks suggest misaligned transiting examples could also plausibly exist, but their existence would exacerbate the already challenging feat of automatic detection. In this work, we synthesize populations of such planets and consider the number of transits per epoch they produce, forming integer sequences. For isotropic distributions, such sequences will appear foreign to conventional expectation, rarely (~1%) producing the signature double-transits we have come to expect for circumbinaries, instead producing sparse sequences dominated by zero-transit epochs (~80%). Despite their strangeness, we demonstrate that these sequences will be non-random and that the two preceding epochs predict the next to high accuracy. Additionally, we show that even when clustering the transits into grouped epochs, they often appear unphysical if erroneously assuming a single star, due to the missing epochs. Crucially, missing epochs mean highly isotropic populations can trick the observer into assigning the wrong period in up to a quarter of cases, adding further confusion. Finally, we show that the transit sequences encode the inclination distribution and demonstrate a simple inference method that successfully matches the injected truth. Our work highlights how the simple act of flagging transits can be used to provide an initial, vetting-level analysis of misaligned transiting circumbinary planets.