Imaging low-mass planets within the habitable zone of α Centauri

The sensitivity of direct imaging of extrasolar planets could be increased tenfold by installing, under ESO supervision, the CEA-Irfu-built VISIR instrument on Yepun, one of the VLT telescopes, equipped with an integrated adaptive optics system. A 100-hour campaign in 2019 revealed an image that could be of a planet orbiting the star Alpha Centauri A 4.4 light-years away.

Abstract: Giant exoplanets on wide orbits have been directly imaged around young stars. If the thermal background in the mid-infrared can be mitigated, then exoplanets with lower masses can also be imaged. Here we present a ground-based mid-infrared observing approach that enables imaging low-mass temperate exoplanets around nearby stars, and in particular within the closest stellar system, α Centauri. Based on 75–80% of the best quality images from 100 h of cumulative observations, we demonstrate sensitivity to warm sub-Neptune-sized planets throughout much of the habitable zone of α Centauri A. This is an order of magnitude more sensitive than state-of-the-art exoplanet imaging mass detection limits. We also discuss a possible exoplanet or exozodiacal disk detection around α Centauri A. However, an instrumental artifact of unknown origin cannot be ruled out. These results demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes.