Project Hephaistos - I. Upper limits on partial Dyson spheres in the Milky Way

• Dyson spheres are hypothetical megastructures built by advanced extraterrestrial civilizations to harvest radiation energy from stars. Here, we combine optical data from Gaia DR2 with mid-infrared data from AllWISE to set the strongest upper limits to date on the prevalence of partial Dyson spheres within the Milky Way, based on their expected waste-heat signatures. Conservative upper limits are presented on the fraction of stars at G <= 21 that may potentially host non-reflective Dyson spheres that absorb 1-90 per cent of the bolometric luminosity of their host stars and emit thermal waste-heat in the 100-1000 K range. Based on a sample of approximate to 2.7 x 10(5) stars within 100 pc, we find that a fraction less than approximate to 2 x 10(-5) could potentially host similar to 300 K Dyson spheres at 90 per cent completion. These limits become progressively weaker for less complete Dyson spheres due to increased confusion with naturally occurring sources of strong mid-infrared radiation, and also at larger distances, due to the detection limits of WISE. For the similar to 2.9 x 10(8) stars within 5 kpc in our Milky Way sample, the corresponding upper limit on the fraction of stars that could potentially be similar to 300 K Dyson spheres at 90 per cent completion is less than or similar to 8 x 10(-4).

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

Extraterrestrial intelligence

infrared: stars

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)