Possible Dynamical Pathways to the Misalignment of the VHS 1256–1257 System

Read full text
Authors: Liz Holzknecht, Smadar Naoz, Cheyanne E. Shariat
Cited by: 1
References: 120

Abstract

Abstract Circumbinary planets (CBPs) provide a unique window into planet formation and dynamical evolution in complex gravitational environments. Their orbits are shaped not only by the protoplanetary disk but also by the perturbations from two stellar hosts, making them sensitive probes of both early- and late-stage dynamical processes. In this work, we investigate the unusual architecture of the VHS J125601.92−125723.9 system, where a retrograde, nearly polar tertiary orbits an extremely low-mass substellar binary in a hierarchical triple configuration. We find that triple-body dynamics can naturally reproduce the observed high eccentricity of the inner binary and the tertiary’s near-polar obliquity. However, this configuration alone cannot account for the observed mutual inclination, which is both near-polar and retrograde. This tension suggests two possible formation pathways: either the planet formed in an aligned, protoplanetary disklike configuration and was later tilted by an additional, undetected fourth companion (below current Gaia limits), or the system formed close to its current state. Stellar flybys, in contrast, are unlikely due to their long timescales. Our results highlight both the explanatory power and the limitations of triple dynamics, and the potential role of hidden companions in shaping extreme planetary architectures.

Fields of Study & Subjects

Astrophysics and Star Formation Studies Stellar planetary and galactic studies Astronomy and Astrophysical Research

Publication details

Journal / source
The Astrophysical Journal
Publisher
American Astronomical Society
Volume
998
Issue
1
Pages
122–122
Publication date
5 February 2026
Language
EN