We have observed the CN features at \sim 3800 Å and 4120 Å as well as the CH band at \sim 4300 Å for 145 evolved stars in the Galactic globular cluster M71 using the multi-object spectrograph , Hydra , on the WIYN-3.5m telescope .
We use these measurements to create two \delta CN indices finding that both distributions are best fit by two populations , a CN-enhanced and CN-normal .
We find that 42 \pm 4 % of the RGB stars in our sample are CN-enhanced .
The percentage of CN-enhanced is 40 \pm 13 % for the AGB and 33 \pm 9 % for the HB stars , which suggests there are no missing second generation stars at these stages of stellar evolution .
The two generations also separate in magnitude and color on the HB , which allows us to find the difference in He abundance between the two populations by fitting appropriate ZAHBs .
The broad range of distances from the cluster ’ s center covered by our sample allows us to study the dependence of the ratio of the number of first to second population stars on the distance from the cluster ’ s center , and we find that this ratio does not vary radially and that the two populations are spatially mixed .
Finally , we compare our identification of multiple populations with the classification based on the Na-O anti-correlation and the HST UV photometry , and we find good agreement with both methods .