  Keplerian-Stacker is an algorithm able to combine multiple observations
acquired at different epochs taking into account the orbital motion of a
potential planet present in the images to boost the ultimate detection limit.
In 2019, a total of 100 hours of observation were allocated to VLT VISIR-NEAR,
a collaboration between ESO and Breakthrough Initiatives, to search for low
mass planets in the habitable zone of the Alpha Cen AB binary system. A weak
signal (S/N = 3) was reported around Alpha Cen A, at a separation of 1.1 a.u.
which corresponds to the habitable zone. We have re-analysed the NEAR data
using K-Stacker. This algorithm is a brute-force method able to find planets in
time series of observations and to constrain their orbital parameters, even if
they remain undetected in a single epoch. We scanned a total of about 3.5e+5
independent orbits, among which about 15 % correspond to fast moving orbits on
which planets cannot be detected without taking into account the orbital
motion. We find only a single planet candidate, which matches the C1 detection
reported in Wagner et al. 2021. Despite the significant amount of time spent on
this target, the orbit of this candidate remains poorly constrained due to
these observations being closely distributed in 34 days. We argue that future
single-target deep surveys would benefit from a K-Stacker based strategy, where
the observations would be split over a significant part of the expected orbital
period to better constrain the orbital parameters. This application of
K-Stacker on high contrast imaging data in the mid-infrared demonstrates the
capability of this algorithm to aid in the search for Earth-like planets in the
habitable zone of the nearest stars with future instruments of the E-ELT such
as METIS.
