  A direct measure of the helium abundances from the near-infrared transition
of He I at 1.08 micron is obtained for two nearly identical red giant stars in
the globular cluster Omega Centauri. One star exhibits the He I line; the line
is weak or absent in the other star. Detailed non-LTE semi-empirical models
including expansion in spherical geometry are developed to match the
chromospheric H-alpha, H-beta, and Ca II K lines, in order to predict the
helium profile and derive a helium abundance. The red giant spectra suggest a
helium abundance of Y less than or equal 0.22 (LEID 54064) and Y=0.39-0.44
(LEID 54084) corresponding to a difference in the abundance Delta Y greater or
equal than 0.17.Helium is enhanced in the giant star (LEID 54084) that also
contains enhanced aluminum and magnesium. This direct evaluation of the helium
abundances gives observational support to the theoretical conjecture that
multiple populations harbor enhanced helium in addition to light elements that
are products of high-temperature hydrogen burning. We demonstrate that the 1.08
micron He I line can yield a helium abundance in cool stars when constraints on
the semi-empirical chromospheric model are provided by other spectroscopic
features.
