We present new BVI photometry of the globular cluster ( catalog NGC~6981 ) ( M72 ) , based mostly on ground-based CCD archive images .
We present a new color-magnitude diagram ( CMD ) that reaches almost four magnitudes below the turn-off level .
We performed new derivations of metallicity and morphological parameters of the evolved sequences , in good agreement with previous authors , obtaining a value of { [ Fe / H ] } \simeq - 1.50 in the new UVES scale .
We also identify the cluster ’ s blue straggler population .
Comparing the radial distribution of these stars with the red giant branch population , we find that the blue stragglers are more centrally concentrated , as found in previous studies of blue stragglers in globular clusters .
Taking advantage of the large field of view covered by our study , we analyzed the surface density profile of the cluster , finding extratidal main sequence stars out to r \approx 14.1 \arcmin , or about twice the tidal radius .
We speculate that this may be due to tidal disruption in the course of M72 ’ s orbit , in which case tidal tails associated with the cluster may exist .
We also take a fresh look at the variable stars in the cluster , recovering all previous known variables , including three SX Phoenicis stars , and adding three previously unknown RR Lyrae ( 1 c-type and 2 ab-type ) to the total census .
Finally , comparing our CMD with unpublished data for M3 ( NGC 5272 ) , a cluster with similar metallicity and horizontal branch morphology , we found that both objects are essentially coeval .