  The He I 1 micron line is a high excitation line which allows us to probe the
innermost regions of protostellar disks, and to trace both accreting and
outflowing material. We use X-Shooter observations of a sample of 107 young
stars in the Lupus (1-3 Myr) and Upper Scorpius (5-10 Myr) star-forming regions
to search for correlations between the line properties, as well as the disk
inclination and accretion luminosity. We identified eight distinct profile
types in the sample. We fitted Gaussian curves to the line features to measure
the maximum velocities traced in absorption, the full-width half-maximum (FWHM)
of the line features, and the Gaussian area of the features. We compare the
proportion of each profile type in our sample to previous studies in Taurus. We
find significant variations between Taurus and Lupus in the proportion of P
Cygni and inverse P Cygni profiles, and between Lupus and Upper Scorpius in the
number of emission-only and combination profile types. We find that the
blue-shifted absorption features appear less blue-shifted at disk inclinations
close to edge-on, but no such trend with inclination is observed in sources
with only red-shifted features. Higher accretion rates were observed in sources
with strong blue-shifted features which, along with the changes in the
proportions of each profile type observed in the two regions, indicates that
younger sources may drive stronger jets or winds. Overall, we observe
variations in the proportion of each profile type and in the line properties
which indicates and evolution of accretion and ejection signatures over time,
and with source properties. These results confirm past works and models of the
He I line, but for a larger sample and for multiple star-forming regions. The
work highlights the power of the He I line as a probe of the gas in the
innermost regions of the disk.
