Astronomers pointed JWST at a planet near the star Epsilon Indi — a giant gas ball resembling Jupiter, just 12 light-years away. In thermal images, the planet shone like a lantern. But nearby they noticed a faint dot — like a firefly. Calculations showed that two objects describe the picture better than one. However, it's most likely a lens flare — like a ghost of a lamp. Still, we can’t rule out a pair of massive bodies circling each other.
The telescope’s sensitivity is impressive: it clearly sees objects 30 times fainter than the main planet, even at temperatures of −130°C — colder than any earthly freeze. Measurements of light allowed calculating at what distance moons can be discovered. JWST is now capable, for the first time, of directly photographing moons of other worlds or entire double planets.
as written by the authors arXiv:2604.23448
Epsilon Indi A b is a directly imaged $$\sim6 M_{\rm Jup}$$ exoplanet orbiting a nearby (3.6 pc) K-dwarf at $$\sim 30$$ AU. We analyze archival JWST/MIRI 15 $$\mu$$m coronagraphic imaging of this planet to search for directly imaged satellites orbiting Eps Ind A b. Within the planet's Hill sphere (radius $$R_H \approx 2.3$$ AU or $$1.3 \lambda/D$$), we compare single- and double-PSF models using Bayesian evidence. We find that a double-PSF (binary planet) fit is preferred. This apparent preference can most plausibly be explained by systematics, although follow-up observations would be required to fully rule out a binary planet interpretation. We construct a contrast curve of the exoplanet after removing this feature, demonstrating sensitivity to companions as faint as $$0.03\times$$ the F1550C flux of Eps Ind A b (equivalent to $$T = 130$$ K, $$1.3 M_{\rm Jup}$$) at large separations (>2 AU). We also demonstrate sensitivity to brighter companions $$0.2\times$$ the F1550C flux of Eps Ind A b (equivalent to $$T = 180$$ K, $$2.5 M_{\rm Jup}$$) down to separations of 0.52 AU (1.3 pixels; $$0.29 \lambda/D$$; 144 mas). This study demonstrates that JWST/MIRI can directly detect exomoons or binary planets inside the Hill sphere of directly imaged exoplanets orbiting neighboring stars.
A year on this planet lasts nearly 50 Earth years — it's farther from its sun than Neptune is from ours.