  Herbig Ae/Be stars lie in the mass range between low and high mass young
stars, and therefore offer a unique opportunity to observe any changes in the
formation processes that may occur across this boundary. This paper presents
medium resolution VLT/X-Shooter spectra of six Herbig Ae/Be stars, drawn from a
sample of 91 targets, and high resolution VLT/CRIRES spectra of five Herbig
Ae/Be stars, chosen based on the presence of CO first overtone bandhead
emission in their spectra. The X-Shooter survey reveals a low detection rate of
CO first overtone emission (7 per cent), consisting of objects mainly of
spectral type B. A positive correlation is found between the strength of the CO
v=2-0 and Br {\gamma} emission lines, despite their intrinsic linewidths
suggesting a separate kinematic origin. The high resolution CRIRES spectra are
modelled, and are well fitted under the assumption that the emission originates
from small scale Keplerian discs, interior to the dust sublimation radius, but
outside the co-rotation radius of the central stars. In addition, our findings
are in very good agreement for the one object where spatially resolved
near-infrared interferometric studies have also been performed. These results
suggest that the Herbig Ae/Be stars in question are in the process of gaining
mass via disc accretion, and that modelling of high spectral resolution spectra
is able to provide a reliable probe into the process of stellar accretion in
young stars of intermediate to high masses.

Solar and Stellar Astrophysics