The study of exoplanetary atmospheres is key to understand the differences
between their physical, chemical and dynamical processes. Up to now, the bulk
of atmospheric characterization analysis has been conducted on transiting
planets. On some sufficiently bright targets, high-resolution spectroscopy
(HRS) has also been successfully tested for non-transiting planets. We study
the dayside of the non-transiting planet HD 102195b using the GIANO
spectrograph mounted at TNG, demonstrating the feasibility of atmospheric
characterization measurements and molecular detection for non-transiting
planets with the HRS technique using 4-m class telescopes. The Doppler-shifted
planetary signal changes on the order of many km/s during the observations, in
contrast with the telluric absorption which is stationary in wavelength,
allowing us to remove the contamination from telluric lines while preserving
the features of the planetary spectrum. The emission signal from HD 102195b's
atmosphere is then extracted by cross-correlating the residual spectra with
atmospheric models. We detect molecular absorption from water vapor at
4.4σ level. We also find convincing evidence for the presence of
methane, which is detected at the 4.1σ level. The two molecules are
detected with a combined significance of 5.3σ, at a semi-amplitude of
the planet radial velocity KP=128±6 km/s. We estimate a planet true mass
of MP=0.46±0.03MJ and orbital inclination between 72.5 and
84.79∘ (1σ). Our analysis indicates a non-inverted atmosphere
for HD 102195b, as expected given the relatively low temperature of the planet,
inefficient to keep TiO/VO in gas phase. Moreover, a comparison with
theoretical expectations and chemical model predictions corroborates our
methane detection and suggests that the detected CH4 and H2O signatures
could be consistent with a low C/O ratio.Comment: 12 pages, 12 figures, accepted for publication in A&
