The Complex High Mass Star Formation Region S255-2

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Session 82 -- HII Regions
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[82.06] The Complex High Mass Star Formation Region S255-2

Eric M. Howard, Judith L. Pipher and William J. Forrest (University of Rochester)

In an ongoing study of star formation regions in the near (1-5$\mu$m) infrared, we present J (1.2$\mu$m, H (1.65$\mu$m), K (2.23$\mu$m), and 3.3$\mu$m broadband images as well as Br$\gamma$ (n = 7$\rightarrow$4, 2.166$\mu$m) and Br$\alpha$ (n = 5$\rightarrow$4, 4.052$\mu$m) hydrogen recombination line images, H$_2$ (1-0 S(1), 2.122$\mu$m) line images, and 3.29$\mu$m unidentified dust feature emission images of the triple HII region S255-2, at a plate scale of $\sim$0.33'' per pixel. The Br$\alpha$ and Br$\gamma$ emission is larger than that predicted by the radio emission from the $\sim$20'' region around the 3 compact sources for case B recombination. The ${Br\alpha \over Br\gamma}$ ratio is unusually large for a $\sim$5'' region surrounding the western source. The 3.29$\mu$m emission and the H$_2$ is found in a bubble like region that overlaps and extends beyond the Br$\alpha$ and Br$\gamma$ emission into the photodisociation region (PDR). Excess hydrogen line emission may be due to accretion, stellar winds giving rise to extended atmospheres, high density and optical depth, a core-halo structure supported by the sub-Lyman continuum, or some combination of effects.

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