  [Abridged] After many attempts over more than a decade, high-resolution
spectroscopy has recently delivered its first detections of molecular
absorption in exoplanet atmospheres, both in transmission and thermal emission
spectra. Targeting the combined signal from individual lines in molecular
bands, these measurements use variations in the planet radial velocity to
disentangle the planet signal from telluric and stellar contaminants. In this
paper we apply high resolution spectroscopy to probe molecular absorption in
the day-side spectrum of the bright transiting hot Jupiter HD 189733b. We
observed HD 189733b with the CRIRES high-resolution near-infrared spectograph
on the Very Large Telescope during three nights. We detect a 5-sigma absorption
signal from CO at a contrast level of ~4.5e-4 with respect to the stellar
continuum, revealing the planet orbital radial velocity at 154+4/-3 km s-1.
This allows us to solve for the planet and stellar mass in a similar way as for
stellar eclipsing binaries, resulting in Ms= 0.846+0.068/-0.049 Msun and Mp=
1.162+0.058/-0.039 MJup. No significant absorption is detected from H2O, CO2 or
CH4 and we determined upper limits on their line contrasts here. The detection
of CO in the day-side spectrum of HD 189733b can be made consistent with the
haze layer proposed to explain the optical to near-infrared transmission
spectrum if the layer is optically thin at the normal incidence angles probed
by our observations, or if the CO abundance is high enough for the CO
absorption to originate from above the haze. Our non-detection of CO2 at 2.0
micron is not inconsistent with the deep CO2 absorption from low resolution
NICMOS secondary eclipse data in the same wavelength range. If genuine, the
absorption would be so strong that it blanks out any planet light completely in
this wavelength range, leaving no high-resolution signal to be measured.
