The Occurrence of Wide-Orbit Planets in Binary Star Systems

TL;DR

This study uses white dwarf atmospheric composition to estimate the frequency of wide-orbit planets in binary systems, revealing that such planets are as common as around single stars when the binary separation exceeds 1000 AU.

Contribution

It introduces a novel method to detect wide-orbit planets in binary systems and provides new insights into how binary separation affects planetary system formation and stability.

Findings

Wide-orbit planets are as common in binaries with >1000 AU separation as around single stars.

Secondary stars within 1000 AU tend to suppress the formation or stability of extended planetary systems.

The method offers a new way to study planetary occurrence beyond traditional detection techniques.

Abstract

The occurrence of planets in binary star systems has been investigated via a variety of techniques that sample a wide range of semi-major axes, but with a preponderance of such results applicable to planets with semi-major axes less than a few AU. We utilize a new method -- the presence or absence of heavy elements in the atmospheres of white dwarf stars -- to elucidate the frequency in main sequence binary star systems of planets with semi-major axes greater than a few AU. We consider only binaries where a putative planetary system orbits one member (no circumbinary planets). For main sequence binaries where the primary star is of spectral type A or F, data in the published literature suggests that the existence of a secondary star with a semi-major axis less than about 1000 AU suppresses the formation and/or long term stability of an extended planetary system around the primary. For these spectral types and initial semi-major axis $\geq$1000 AU, extended planetary systems appear to be as common around stars in binary systems as they are around single stars.