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| EPoS Contribution |
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"Footprint" outflow features around ultracompact H II regions imaged in [Fe II] 1.644 um
Jong-Ho Shinn KASI, Daejeon, KR | |
| We present "footprint" outflow features around ultracompact H II regions (UCHIIs), which may be produced by the outflowing materials ejected during the earlier, active accretion phase of massive young stellar objects. These "footprint" outflow features are useful in clarifying the accretion process, since we can tell if massive stars form as low-mass stars through disk accretion with jet-like outflow, and guess the almost-final stellar mass where the disk accretion works. We surveyed 240 UCHIIs in the 1st Galactic quadrant, employing the CORNISH UCHII catalog and UWIFE data which is an imaging survey in [Fe II] 1.644 um performed with UKIRT-WFCAM under ~0.8" seeing condition. The "footprint" outflow features were found around four UCHIIs with high plausibility and one UCHII with low plausibility. The outflow mass loss rates estimated from the [Fe II] flux are ~10-6 - 10-5 Ms/yr. The outflow mass loss rate show no evident relation with the peak flux density of UCHIIs, although the sample number is small. We found many point sources with infrared excess around UCHIIs. These sources are able to produce the detected [Fe II] features, hence more investigation on the properties of the [Fe II] features are required. | |
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| Caption: Outflow features around two UCHIIs G025.3824-00.1812 (upper-circle) and G025.3809-00.1815 (lower-circle) seen in the continuum-subtracted [Fe II] (top panels) and RGB composite (middle panels; R=[Fe II], G=H, B=H) images. The CORNISH 5 GHz image is shown for reference in the bottom-left panel. The dashed boxes in the left panels indicate the region enlarged in the right panels. Ellipses indicate where the flux is measured (on-source: solid, off-source: dashed). | |
| Collaborators: J.-J. Lee, KASI, KR H.-J. Kim, SNU, KR Y.-H. Lee, SNU, KR B.-C. Koo, SNU, KR J. Kyeong, KASI, KR |
Suggested Session:
Massive Star Formation and Feedback |