S255-2: The formation of a stellar cluster

As part of an ongoing study of high-mass star formation regions, we have imaged the S255-2 triple H II region in near-infrared broadband wavelength bands J (1.23 mu m), H (1.65 mu m), K (2.23 mu m), and at 3.3 mu m. We have also obtained images in the Br gamma and Br alpha hydrogen recombination lines, in the H-2, v = 1-->0 S(1) line, and in the 3.29 mu m dust feature emission band. The region consists of a circular core of stars and young stellar objects, as well. as nebulosity, and a more diffuse stellar cluster. The Brackett-line emission from the region is at least a factor of 10 greater than the value estimated from the radio continuum flux density, assuming case B recombination. The strongest Br alpha line emission object is IRS 1b, which appears to be an ionizing wind source. The central core region contains a narrow band of Br gamma and H-2 emission that we postulate is an ionized jet. The 3.29 mu m and the H-2 emission are found in a bubble-like region that overlaps and extends beyond the Br alpha and Br gamma emission into the photodissociation region. S255-2 appears to be a young cluster of stars still in the process of forming.