As part of a large investigation with Hubble Space Telescope to study the faintest stars within the globular cluster \omega Centauri , in this work we present early results on the multiplicity of its main sequence ( MS ) stars , based on deep optical and near-infrared observations .
By using appropriate color-magnitude diagrams we have identified , for the first time , the two main stellar populations I , and II along the entire MS , from the turn-off towards the hydrogen-burning limit .
We have compared the observations with suitable synthetic spectra of MS stars and conclude that the two MSs are consistent with stellar populations with different metallicity , helium , and light-element abundance .
Specifically , MS-I corresponds to a metal-poor stellar population ( [ Fe/H ] \sim - 1.7 ) with Y \sim 0.25 and [ O/Fe ] \sim 0.30 .
The MS-II hosts helium-rich ( Y \sim 0.37 - 0.40 ) stars with metallicity ranging from [ Fe/H ] \sim - 1.7 to -1.4 .

Below the MS knee ( m _ { F 160 W } \sim 19.5 ) , our photometry reveals that each of the two main MSs hosts stellar subpopulations with different oxygen abundances , with very O-poor stars ( [ O/Fe ] \sim - 0.5 ) populating the MS-II .
Such a complexity has never been observed in previous studies of M-dwarfs in globular clusters .
A few months before the lunch of the James Webb Space Telescope , these results demonstrate the power of optical and near-infrared photometry in the study of multiple stellar populations in globular clusters .