Thermal-IR Detection of Optical Outflow Sources in OMC1 South

Abstract

We present the first thermal-infrared imaging photometry for several embedded sources in the OMC1 South cloud core in the Orion nebula, and propose that some of these drive optical Herbig-Haro jets emerging from the region. Thermal-infrared images at 8.8 and 11.7 micron obtained at Gemini South show a handful of sources in OMC1-S 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 micron photometry obtained with the Keck telescope. The most prominent blueshifted outflows in the Orion nebula at visual wavelengths such as HH202, HH203/204, HH529, and HH269 all originate from OMC1-S. The brightest infrared source in OMC1-S at 11.7 micron is located at the base of the prominent jet that powers HH202 and is likely to be the sought-after driver of this outflow. The second brightest infrared source is located at the base of the HH529 jet. We consider the possibility that HH203/204 and HH269 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 OMC1-S.