Evolutionary and Observational Consequences of Dyson Sphere Feedback

TL;DR

This paper investigates how Dyson sphere feedback, the light reflected or re-emitted back to stars, influences stellar evolution and observability, especially in high-temperature or highly reflective structures, with implications for technosignature searches.

Contribution

It introduces models showing how Dyson sphere feedback affects star structure and evolution, highlighting conditions where feedback impacts observations.

Findings

Low mass stars are strongly affected by feedback due to convection.

High mass stars with radiative exteriors are less affected.

Significant observational effects occur only for very hot or highly reflective Dyson spheres.

Abstract

The search for signs of extraterrestrial technology, or technosignatures, includes the search for objects which collect starlight for some technological use, such as those composing a Dyson sphere. These searches typically account for a star's light and some blackbody temperature for the surrounding structure. However, such a structure inevitably returns some light back to the surface of its star, either from direct reflection or thermal re-emission. In this work, we explore how this feedback may affect the structure and evolution of stars, and when such feedback may affect observations. We find that in general this returned light can cause stars to expand and cool. Our MESA models show that this energy is only transported toward a star's core effectively by convection, so low mass stars are strongly affected, while higher mass stars with radiative exteriors are not. Ultimately, the effect only has significant observational consequences for spheres with very high temperatures (much higher than the often assumed ~300 K) and/or high specular reflectivity. Lastly, we produce color-magnitude diagrams of combined star-Dyson sphere systems for a wide array of possible configurations.