OUTFLOW-CONFINED H ii REGIONS. I. FIRST SIGNPOSTS OF MASSIVE STAR FORMATION

Outflow - Confined H II Regions and the Formation of Massive Stars by Accretion

If massive stars form by disk accretion, then bipolar outflows should be generated as in the case of low-mass star formation. High accretion rates lead to high outflow rates and make the wind density very large near the protostar. We therefore predict that massive protostars have very small, jet-like H II regions confined by their outflows; we identify these H II regions with “hypercompact” (≤ ...

Masers as Kinemati Signposts in Star Formation Regions

MSX Mid Infrared Imaging of Massive Star Birth Environments. I: Ultracompact H ii Regions

We present mid-IR 21μm images of a sample of radio selected Ultracompact H ii (UCH ii) regions, obtained with the Midcourse Space Experiment (MSX). All, with one possible exception, are detected at mid-IR wavelengths, sampling the warm dust emission of the cocoons of the OB star central exciting sources. Many of the UCH ii regions have nearby (up to ≈ few pc distant) companion dust emission sou...

Outflow and Accretion in Massive Star Forming Regions

In order to distinguish between the various components of massive star forming regions (i.e. infalling, outflowing and rotating gas structures) within our own Galaxy, we require high angular resolution observations which are sensitive to structures on all size scales. To this end, we present observations of the molecular and ionized gas towards massive star forming regions at 230 GHz from the S...

Outflow and Infall in a Sample of Massive Star Forming Regions II: Large Scale Kinematics

We present maps of seven sources selected from Klaassen & Wilson (2007a) in SiO (J=8-7) and HCO and HCO (J=4-3) which were obtained using HARPB on the James Clerk Maxwell Telescope. We find that four out of our seven sources have infall signatures based on their HCO emission profiles. From our maps, we have determined the extent of both the outflowing and infalling regions towards these sources...