  The double main sequence identified in the globular cluster Omega Centauri
has been interpreted using isochrones to indicate a large variation in the
abundance of helium. If true, a helium enhancement carries strong implications
for the chemical and stellar evolutionary history of this cluster. However,
only indirect measures currently support this conjecture. We report the
discovery of a variation in the line strength of the near-infrared He I 10830 A
transition in twelve similar red giants in Omega Centauri observed with PHOENIX
on Gemini-S. Abundances of these stars derived from Magellan/MIKE spectra taken
at Las Campanas Observatory show that the helium transition is not detected in
the most metal-poor population ([Fe/H] < -1.8), yet is present in the majority
of stars with [Fe/H] >= -1.8. These observations give the first direct evidence
for an enhancement of helium in Omega Centauri. The appearance of helium
appears better correlated with increased [Al/Fe] and [Na/Fe] abundances than as
a function of [Fe/H], giving observational support to the presence of
high-temperature H-burning in a prior generation of stars.
