Technosignature Research Portal

Stellar engines are hypothesized megastructures that extract energy from the host star, typically with the purpose of generating thrust and accelerating the stellar system. We explore the maximum potential speeds that could be realizable by stellar engines, and determine that speeds up to ∼0.1c might perhaps be attainable under optimal conditions. In contrast, natural astrophysical phenomena in the Milky Way are very unlikely to produce such speeds. Hence, astrometric surveys of hypervelocity stars may place constraints on the abundance of high-speed stellar engines in the Milky Way. In particular, Gaia DR-2 suggests that less than one in ∼107 stars is propelled by stellar engines to speeds ≳0.01c.