Dyson spheres on H-R diagram

TL;DR

This paper models the observational signatures of hypothetical Dyson spheres around white dwarfs and M-dwarfs, analyzing their temperature, luminosity, and infrared emission to guide future extraterrestrial techno-signature searches.

Contribution

It provides a detailed theoretical analysis of Dyson spheres' properties around different star types and their placement on the H-R diagram for observational purposes.

Findings

Dyson spheres around white dwarfs emit cooler, infrared radiation.

Spheres around M-dwarfs radiate more strongly at longer wavelengths.

Equilibrium temperature scales as R_D^-1/2, with fixed stellar luminosity.

Abstract

The construction of Dyson spheres, megastructures designed to capture the total radiative output of stars, can be one of the most compelling techno-signature scenarios for advanced extraterrestrial civilizations. By considering equilibrium temperatures, we investigate the luminosities and fluxes of Dyson spheres built around two promising classes of host stars: white dwarfs and red M-dwarfs. Using radiative balance arguments and representative stellar parameters, we compute the temperature-radius relationship for full energy interception and place these hypothetical structures on the Hertzsprung-Russell (H-R) diagram to assess their observational signatures. Our results show that Dyson spheres around white dwarfs produce cooler and fainter blackbody emissions, peaking in the near- to mid-infrared, while those around M-dwarfs radiate more strongly but at longer wavelengths. In both cases, the equilibrium temperature decreases as R_ D^-1/2, while the total luminosity and observed bolometric flux remain fixed by the stellar output. These findings highlight the astrophysical suitability of low-luminosity stars as Dyson sphere hosts and provide practical constraints for future techno-signature searches using infrared surveys.