We obtained deep near-infrared images of Sh 2-208 , one of the lowest-metallicity H ii regions in the Galaxy , { [ O / H ] } = -0.8 dex .
We detected a young cluster in the center of the H ii region with a limiting magnitude of K = 18.0 mag ( 10 \sigma ) , which corresponds to a mass detection limit of \sim 0.2 M _ { \odot } .
This enables the comparison of star-forming properties under low metallicity with those of the solar neighborhood .
We identified 89 cluster members .
From the fitting of the K -band luminosity function ( KLF ) , the age and distance of the cluster are estimated to be \sim 0.5 Myr and \sim 4 kpc , respectively .
The estimated young age is consistent with the detection of strong CO emission in the cluster region and the estimated large extinction of cluster members ( A _ { V } \sim 4 –25 mag ) .
The observed KLF suggests that the underlying initial mass function ( IMF ) of the low-metallicity cluster is not significantly different from canonical IMFs in the solar neighborhood in terms of both high-mass slope and IMF peak ( characteristic mass ) .
Despite the very young age , the disk fraction of the cluster is estimated at only 27 \pm 6 % , which is significantly lower than those in the solar metallicity .
Those results are similar to Sh 2-207 , which is another low-metallicity star-forming region close to Sh 2-208 with a separation of 12 pc , suggesting that their star-forming activities in low-metallicity environments are essentially identical to those in the solar neighborhood , except for the disk dispersal timescale .
From large-scale mid-infrared images , we suggest that sequential star formation is taking place in Sh 2-207 , Sh 2-208 and the surrounding region , triggered by an expanding bubble with a \sim 30 pc radius .