Photometric CCD UBVI _ { C } photometry obtained for 4860 stars surrounding the embedded southern cluster SAI 113 ( Skiff 8 ) is used to examine the reddening in the field and derive the distance to the cluster and nearby van Genderen 1 .
Spectroscopic color excesses for bright cluster stars , photometric reddenings for A3 dwarfs , and dereddening of cluster stars imply that the reddening and extinction laws match results derived for other young clusters in Carina : E _ { U - B } / E _ { B - V } \simeq 0.64 and R _ { V } \simeq 4 .
SAI 113 displays features that may be linked to a history of dynamical interactions among member stars : possible circumstellar reddening and rapid rotation of late B-type members , ringlike features in star density , and a compact core with most stars distributed randomly across the field .
The group van Genderen 1 resembles a stellar asterism , with potential members distributed randomly across the field .
Distances of 3.90 \pm 0.19 kpc and 2.49 \pm 0.09 kpc are derived for SAI 113 and van Genderen 1 , respectively , with variable reddenings E _ { B - V } ranging from 0.84 to 1.29 and 0.23 to 1.28 .
The SRC variables CK Car and EV Car may be outlying members of van Genderen 1 , thereby of use for calibrating the period-luminosity relation for pulsating M supergiants .
More importantly , the anomalous reddening and extinction evident in Carina and nearby regions of the Galactic plane in the fourth quadrant impact the mapping of spiral structure from young open clusters .
The distribution of spiral arms in the fourth quadrant may be significantly different from how it is often portrayed .