Searching for Multiple Populations in the Integrated Light of the Young
  and Extremely Massive Clusters in the Merger Remnant NGC~7252
  Recent work has shown that the properties of multiple populations within
massive stellar clusters (i.e., in the extent of their abundance variations as
well as the fraction of stars that show the anomalous chemistry) depend on the
mass as well as the age of the host cluster. Such correlations are largely
unexpected in current models for the formation of multiple populations and
hence provide essential insight into their origin. Here we extend or previous
study into the presence or absence of multiple populations using integrated
light spectroscopy of the $\sim600$~Myr, massive ($\sim10^7 - 10^8$~\msun)
clusters, W3 and W30, in the galactic merger remnant, NGC 7252. Due to the
extreme mass of both clusters, the expectation is that they should host rather
extreme abundance spreads, manifested through, e.g., high mean [Na/Fe]
abundances. However, we do not find evidence for a strong [Na/Fe] enhancement,
with the observations being consistent with the solar value. This suggests that
age is playing a key role, or alternatively that multiple populations only
manifest below a certain stellar mass, as the integrated light at all ages
above $\sim100$~Myr is dominated by stars near or above the main sequence
turn-off.
