GeMS in the Outer Galaxy: Near-Infrared Imaging of Three Young Clusters
  at Large Galactic Radii
  Images recorded with the Gemini South Adaptive Optics Imager (GSAOI) and
corrected for atmospheric seeing by the Gemini Multiconjugate Adaptive Optics
System (GeMS) are used to investigate the stellar contents of the young outer
Galactic disk clusters Haffner 17, NGC 2401, and NGC 3105. Ages estimated from
the faint end of the main sequence (MS) and the ridgeline of the pre-main
sequence (PMS) on the (K, J-K) color-magnitude diagrams are consistent with
published values that are based on the MS turn-off, with the GSAOI data
favoring the younger end of the age range for NGC 2401 in the literature. The
mass function (MF) of NGC 2401 is similar to that in the Solar neighborhood,
and stars spanning a wide range of masses in this cluster have similar
clustering properties on the sky. It is concluded that NGC 2401 is not evolved
dynamically. In contrast, the MF of Haffner 17 differs significantly from that
in the Solar neighborhood over all masses covered by these data, while the MF
of NGC 3105 is deficient in objects with sub-solar masses when compared with
the Solar neighborhood. Low mass objects in Haffner 17 and NGC 3105 are also
more uniformly distributed on the sky than brighter, more massive, MS stars.
This is consistent with both clusters having experienced significant dynamical
evolution.
