Identification of the Exciting Source of CO Outflow in the Star-Formation Region GGD 12-15

Abstract

We present results of near-infrared imaging polarimetry of the GGD 12-15 region with the IRSF 1.4m telescope and the SIRIUS camera/SIRPOL polarimeter and mid-infrared imaging with the AKARI telescope and the Infra-Red Camera (IRC). Two infrared sources, IRS9E and IRS9M near an H₂O maser source situated on both sides around a VLA source (VLA7), have been believed to be two bipolar lobes associated with a massive CO outflow. However, our polarimetric observations have revealed that IRS9E is stellar-like, and not part of a reflection nebula. Furthermore, IRS9M itself is not stellar, but a bipolar nebula, extending north-south. Both polarization vector maps and polarized intensity images show that the true illuminating source, IRS9Mc, is not resolved, and is situated near the peak of the intensity image. Our astrometry also indicates that the position of IRS9Mc does not coincide with the water maser position, but rather coincides with the VLA7 position. We suggest that the unresolved illuminating source IRS9Mc is the true exciting source of the CO outflow, corresponding to amid-infrared source detected by AKARI with a lower spatial resolution. Fluxes of the newly identified source at 1 to 11μm were derived by separating contributions from nearby infrared sources; the spectral energy distribution is consistent with that of a class I/0 source.