Searching for Dyson spheres with Gaia
Assuming that Dyson spheres obscure optical/near-infrared light as grey absorbers, a partial Dyson sphere with high covering fraction (fcov > 0.5) could reveal itself as an anomalously subluminous star with a parallax-based distance smaller than the spectroscopically inferred one. A large catalog search for objects of this type can currently be carried out by combining parallax distances from Gaia DR1 with spectroscopic distances from RAVE DR5. From the best-fitting stellar parameters provided by RAVE, the PARSEC isochrones on which the RAVE fits are based also provide the predicted WISE fluxes for these stars. A comparison to the observed WISE flux may then reveal any infrared excess associated with waste heat emission from the Dyson sphere at wavelengths < 22 micron. Most of the ~200,000 stars which are common to both data sets have distance errors too large to be useful for this analysis, but searches among subsets of objects with the highest-quality data and fits could be fruitful. Further cuts can be made to exclude objects which are very young (potentially obscured by debris disks), have left the main sequence (potentially subject to circumstellar dust), or for which the stellar parameters favoured by the RAVE and RAVE-on analyses are inconsistent.