Thermal-Infrared Detection of Optical Outflow Sources in OMC-1 South

We present the first thermal-infrared imaging photometry for several embedded sources in the OMC-1 South cloud core in the Orion Nebula, and we propose that some of these drive the optical Herbig-Haro jets emerging from the region. Thermal-infrared images at 8.8 and 11.7 μm obtained at Gemini South show a handful of sources in OMC-1 South with no visual-wavelength counterparts, although a few can be seen in recent near-infrared data. For the three brightest mid-infrared sources, we also present 18.75 μm photometry obtained with the Keck telescope. The most prominent blueshifted outflows in the Orion Nebula at visual wavelengths, such as HH 202, HH 203/204, HH 529, and HH 269, all originate from OMC-1S. The brightest infrared source in OMC-1S at 11.7 μm is located at the base of the prominent jet that powers HH 202 and is likely to be the sought-after driver of this outflow. The second brightest infrared source is located at the base of the HH 529 jet. We consider the possibility that HH 203/204 and HH 269 trace parts of a single bent outflow from the third brightest infrared source. While there may be some lingering ambiguity about which infrared stars drive specific jets, there is now a sufficient number of embedded sources to plausibly account for the multiple outflows from OMC-1S.

Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).