  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, Alpha Centauri. Based on 75-80% of the best quality images from 100
hours of cumulative observations, we demonstrate sensitivity to warm
sub-Neptune-sized planets throughout much of the habitable zone of Alpha
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 Alpha 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.
