  We analyzed the combined near-infrared spectrum of a star-planet system with
thermal emission atmospheric models, based on the composition and physical
parameters of the system. The main objective of this work is to obtain the
inclination of the orbit, the mass of the exoplanet, and the planet-to-star
flux ratio. We present the results of our routines on the planetary system HD
217107, which was observed with the high-resolution spectrograph Phoenix at
2.14 microns. We revisited and tuned a correlation method to directly search
for the high-resolution signature of a known non-transiting extrasolar planet.
We could not detect the planet with our current data, but we present
sensitivity estimates of our method and the respective constraints on the
planetary parameters. With a confidence level of 3--$\sigma$ we constrain the
HD 217107 b planet-to-star flux ratio to be less than $5 \times 10^{-3}$. We
also carried out simulations on other planet candidates to assess the
detectability limit of atmospheric water on realistically simulated data sets
for this instrument, and we outline an optimized observational and selection
strategy to increase future probabilities of success by considering the optimal
observing conditions and the most suitable candidates.
