Project Hephaistos -- IV. James Webb Space Telescope Observations of Two Dyson Sphere Candidates

arXiv:2607.09460 · astro-ph.GA, astro-ph.SR · Submitted 2026-07-10 · Read on arXiv

Erik Zackrisson, Arjan Bik, Anita Ali Asgar, Olivia Curtis, Jason T. Wright, Tongtian Ren, Roberto J. Assef, Andrew Blain, Alexis Brandeker, Michael A. Garrett, Uma Gorti, Andreas J. Korn, Priyatam K. Mahto, Armin Nabizadeh

astro-ph.GA, astro-ph.SR

Submitted: 2026-07-10

Comments: 13 pages, 9 figures

License: http://creativecommons.org/licenses/by/4.0/

The gist: We report on JWST/MIRI imaging and spectroscopy of two M-dwarf stars previously singled out by project Hephaistos as potential Dyson-sphere candidates (their candidates D and E) due to the presence

Terminology

Abstract

We report on JWST/MIRI imaging and spectroscopy of two M-dwarf stars previously singled out by project Hephaistos as potential Dyson-sphere candidates (their candidates D and E) due to the presence of excess flux at mid-infrared wavelengths. We find that the infrared excess does not originate from Dysonian megastructures, or other radiation mechanisms close to these stars, but from background galaxies projected within about 1 arcsec of the M dwarfs, thereby confusing previous mid-infrared photometry obtained with the WISE telescope. The candidate D background galaxy lies at redshift z about 0.9, appears point-source dominated in imaging and has a mid-infrared spectrum consistent with being a Hot Dust Obscured Galaxy (Hot DOG). The candidate E background galaxy lies at z about 0.4, displays an extended morphology with bright knots and a spectrum consistent with a dusty starburst.

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