How To Detect Extraterrestrial Life On Proxima B? (Astronomy)

Elisa Tabor and Abraham Loeb investigated the possibility of detecting artificial lights from proxima b. They found that James Webb Space Telescope will be able to detect LED type artificial lights. Their study recently appeared in Arxiv.

Proxima b as we all know, is one of the best targets outside of solar system in the search for extraterrestrial life. It resides in the habitable zone of its star “Proxima Centauri”. Recent study, suggested that Proxima Centauri b can sustain enormous areas of liquid water on its surface, potentially raising its prospects for harboring extraterrestrial life. The important question is, how can we detect it?

In 2011, Turner and Loeb proposed a concept which relies on the assumption that any intelligent life that evolved in the light from its nearest star is likely to have artificial lights that switches on during the hours of darkness. Considering this, Tabor and Loeb now examined how can we detect such artificial lights originating from Proxima b.

“Proxima Centauri b orbits in its star’s habitable zone, so it’s likely that the planet has become tidally locked with a permanent dayside and nightside. This exacerbates the need for artificial illumination that switches on during the hours of darkness.”

According to authors, if Proxima b has a permanent day and nightside, the civilization might illuminate the nightside using mirrors launched into orbit or placed at strategic points. In that case, the lights shining onto the permanent nightside should be extremely powerful, and thus more likely to be detected with James Webb Space Telescope (JWST).

“We have simulated lightcurves from Proxima b and compared curves corresponding to the reflected stellar spectrum to curves with artificial lights corresponding to a narrower spectrum such as for LEDs”

They have found that JWST will be able to show the existence of artificial illumination for standard LEDs 500 times more powerful than those currently found on Earth’s, and for artificial illumination of similar magnitude to Earth’s for a spectrum 10³ times narrower in frequency.

“We find that the James Webb Space Telescope (JWST) will be able to detect LED type artificial lights making up 5% of stellar power with 85% confidence and for the current level of artificial illumination on Earth, the spectral band must be 10³ times narrower.”

Finally, they concluded that, even if JWST will not be able to detect artificial illumination on Proxima b, future observatories like Large UV Optical Infrared Surveyor (LUVOIR) might be able to detect this artificial illumination.

Figure 1. The lightcurves from Proxima b calculated using Exoplanet Analytic Reflected Lightcurves (EARL), with three different coefficients Fai representing the percentage of stellar power being illuminated on the dark side of the planet. The blue curve represents Fai = 0.1, which equals the value they assume for the albedo. Thus the amount of artificial illumination on the night side is equal to the amount of light reflected from the day side. The green curve, for Fai = 0, represents no artificial illumination, so the night side is fully dark. Top panel: the planet to star ratio depends solely on the lune width. Bottom panel: the ratio depends on time (in days), orbital angular frequency, and inclination. © Tabor and Loeb

Reference: Elisa Tabor, Abraham Loeb, “Detectability of Artificial Lights from Proxima b”, Arxiv, pp. 1-4, 2021.

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