We present high-precision multi-band photometry for the globular cluster ( GC ) M 2 .
We combine the analysis of the photometric data obtained from the Hubble Space Telescope UV Legacy Survey of Galactic GCs GO-13297 , with chemical abundances by Yong et al .
( 2014 ) , and compare the photometry with models in order to analyze the multiple stellar sequences we identified in the color-magnitude diagram ( CMD ) .
We find three main stellar components , composed of metal-poor , metal-intermediate , and metal-rich stars ( hereafter referred to as population A , B , and C , respectively ) .
The components A and B include stars with different s -process element abundances .
They host six sub-populations with different light-element abundances , and exhibit an internal variation in helium up to \Delta Y \sim 0.07 dex .
In contrast with M 22 , another cluster characterized by the presence of populations with different metallicities , M 2 contains a third stellar component , C , which shows neither evidence for sub-populations nor an internal spread in light-elements .
Population C does not exhibit the typical photometric signatures that are associated with abundance variations of light elements produced by hydrogen burning at hot temperatures .
We compare M 2 with other GCs with intrinsic heavy-element variations and conclude that M 2 resembles M 22 , but it includes an additional stellar component that makes it more similar to the central region of the Sagittarius galaxy , which hosts a GC ( M54 ) and the nucleus of the Sagittarius galaxy itself .