Abstract
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 ≈2.7 × 105 stars within 100 pc, we find that a fraction less than ≈2 × 10-5 could potentially host ∼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 ∼2.9 × 108 stars within 5 kpc in our Milky Way sample, the corresponding upper limit on the fraction of stars that could potentially be ∼300 K Dyson spheres at 90 per cent completion is ≲8 × 10-4.
Original language | English (US) |
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Pages (from-to) | 2988-3000 |
Number of pages | 13 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 512 |
Issue number | 2 |
DOIs | |
State | Published - May 1 2022 |
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science