Discovery of Jets and HH‐like Objects near the S255 IR Complex
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Abstract
We report the discovery of two jets and eight HH-like objects in molecular hydrogen near the Sharpless H II region S255 and present near-infrared observations of these objects. The field has been imaged in [Fe II] (1.644 μm), cK (2.26 μm), H2 v = 1 → 0 S(1), and H2 v = 2 → 1 S(1), as well as in broadband JHK' filters, as part of an ongoing near-infrared survey of massive star-forming regions. These observations reveal in detail the morphology of low and intermediate-velocity shocks in the region. The HH-like objects are seen only in H2. The brightest H2 clump is found to the southwest of the S255 IR complex. We see evidence of one possible counterjet: a faint H2 tail to the northeast of S255 IR, seen as a series of clumps. Their arc-shaped geometry is indicative of bow shocks. Diffuse emission is also seen in S255 IR, toward the north and south. K-band long-slit spectroscopy suggests a collisional nature for the brightest H2 object rather than fluorescence. These observations also indicate that the Brγ excess present in S255 IR may be produced by the stellar wind of the very red star NIRS 1, while the H2 diffuse emission may come from collisionally shocked gas present in the extended nebulosity of the region. We also present the results of 12CO (J = 1 → 0) observations of the region. We find two foci of accelerated molecular gas, which suggests the presence of two molecular outflows, one associated with the ultracompact H II region G192.58-0.04 and the other with the S255 IR region and one of the jets.
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