A Tentative Detection of a Point Source in the Disk Gap of HD 100546 with VLT/SPHERE-IRDIS Sparse Aperture Masking Interferometry

TL;DR

This study re-analyzed high-contrast interferometry data of HD 100546, detecting a candidate point source within the disk gap that shows orbital motion, suggesting potential planetary origin but requiring further confirmation.

Contribution

First detection and orbital analysis of a candidate point source in the disk gap of HD 100546 using sparse aperture masking interferometry.

Findings

Candidate point source moved from 39.9 mas to 50.0 mas between 2018 and 2021.

The point source is within the disk gap, supporting a potential planetary interpretation.

Orbital solutions suggest high eccentricity or large inclination, consistent with a bound companion.

Abstract

We re-analyze VLT/SPHERE-IRDIS K and H-band sparse aperture masking interferometry data of the transition disk HD 100546 observed in 2018 and 2021, respectively. We fit geometrical models to the closure phases extracted from both datasets. We compare three model classes: a forward scattering disk, a forward scattering disk plus an arbitrary asymmetric disk feature and a forward scattering disk plus an unresolved point source in the disk-gap. We find that the forward scattering disk plus point source model is the best representation of the data. We find that this point source candidate moved from a position of sep. = $39.9^{+2.8}_{-3.3}$ mas, P.A. = $124.1^{+1.0}_{-1.0}$ degrees to a sep. = $50.0^{+1.0}_{-1.0}$ mas, P.A. = $106.4^{+1.4}_{-1.4}$ degrees between 2018 and 2021. Both of these positions are well within the $\sim$13 au ($\sim$120 mas) disk-gap, favouring the point source interpretation. We explore the orbital parameter space that is consistent with the measured relative astrometry. We find orbits either with a similar orientation to the outer disk, with a high eccentricity $e \gtrapprox 0.65$, or orbits with a large relative inclination ($\sim$60 degrees) to the outer disk, and any eccentricity. Despite the significance of the observed point-source signal, follow-up observations will be necessary to conclusively determine its nature.