Did a close tidal encounter cause the Great Dimming of Betelgeuse?

TL;DR

This paper investigates whether a close tidal encounter could explain Betelgeuse's Great Dimming by modeling gravity darkening effects, concluding such events are unlikely to be the sole cause.

Contribution

The study provides a simplified model to estimate the impact of tidal fly-bys on stellar brightness and applies it to Betelgeuse, offering constraints on possible unseen perturbers.

Findings

Tidal encounters can cause temporary stellar dimming.

Such events are unlikely to fully explain Betelgeuse's dimming.

The method can estimate properties of unseen fly-by objects.

Abstract

We assess whether gravity darkening, induced by a tidal interaction during a stellar fly-by, might be sufficient to explain the Great Dimming of Betelgeuse. Adopting several simple approximations, we calculate the tidal deformation and associated gravity darkening in a close tidal encounter, as well as the reduction in the radiation flux as seen by a distant observer. We show that, in principle, the duration and degree of the resulting stellar dimming can be used to estimate the minimum pericenter separation and mass of a fly-by object, which, even if it remains undetected otherwise, might be a black hole, neutron star, or white dwarf. Our estimates show that, while such fly-by events may occur in other astrophysical scenarios, where our analysis should be applicable, they likely are not large enough to explain the Great Dimming of Betelgeuse by themselves.