Title:

CONDOR Observations of High Mass Star Formation in Orion

Abstract:
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CONDOR, the CO N⁺ Deuterium Observations Receiver, is specifically designed for making velocity-resolved observations of spectral lines in the frequency range 1.2-1.6 THz (190-250 µm). To date, ground-based THz observations have been rare, in part because of the technical difficulty of building instruments for these frequencies, but also because the atmosphere only becomes transparent under exceptionally dry (pwv<0.5mm) conditions.

CONDOR's first observations were made with the APEX telescope in November 2005. With this contribution, we report on some of the initial scientific results from the CONDOR/APEX observations, focusing primarily on observations of the CO J=13-12 emission from high mass star forming regions in Orion. The CO J=13-12 transition traces hot (T_up>500K), dense (P_crit=2x10⁷ cm^-3) gas and is expected to be among the strongest CO lines emitted from hot cores. We present a grid of spectra from the Orion BN/KL complex (Volgenau et al., in prep), a region with a high concentration of deeply embedded, interacting, high-mass stars. The grid is centered on the position of the compact cloud IRc2. The CO J=13-12 line profile from IRc2 itself appears to combine of broad (35 km/s) and narrow (15 km/s) components, but even the broad component is narrower than the extended “plateau” emission seen in lower-J CO transitions (e.g. Kawamura et al. 2002, Wilson et al. 2001).

CONDOR's observations of the hot core Orion FIR4 (Wiedner et al. 2006) reveal a conspicuously narrow (5.4 km/s) line with a single peak centered at 9.0 km/s. There is little evidence for the second velocity component (6.0 km/s) that is seen in lower-J CO observations. The absence of broad line wings suggests that the J=13-12 emission most likely arises from heating by the embedded protostars, rather than shock interactions with outflows. We also present spectra from several lines of sight toward NGC2024 (Emprechtinger et al., in prep).