We present the first ~7.5'×11.5' velocity-resolved (~0.2 km s) map of the [C ii] 158 m line toward the Orion molecular cloud 1 (OMC 1) taken with the/HIFI instrument. In combination with far-infrared (FIR) photometric images and velocity-resolved maps of the H41 hydrogen recombination and CO =2-1 lines, this data set provides an unprecedented view of the intricate small-scale kinematics of the ionized/PDR/molecular gas interfaces and of the radiative feedback from massive stars. The main contribution to the [C ii] luminosity (~85 %) is from the extended, FUV-illuminated face of the cloud (>500, >5×10 cm) and from dense PDRs (≳10, ≳10 cm) at the interface between OMC 1 and the H ii region surrounding the Trapezium cluster. Around ~15 % of the [C ii] emission arises from a different gas component without CO counterpart. The [C ii] excitation, PDR gas turbulence, line opacity (from [C ii]) and role of the geometry of the illuminating stars with respect to the cloud are investigated. We construct maps of the [C ii]/ and / ratios and show that [C ii]/ decreases from the extended cloud component (~10-10) to the more opaque star-forming cores (~10-10). The lowest values are reminiscent of the "[C ii] deficit" seen in local ultra-luminous IR galaxies hosting vigorous star formation. Spatial correlation analysis shows that the decreasing [C ii]/ ratio correlates better with the column density of dust through the molecular cloud than with /. We conclude that the [C ii] emitting column relative to the total dust column along each line of sight is responsible for the observed [C ii]/ variations through the cloud.

We report on our observations of the 79 and 119 µm doublet transitions of OH for 24 local (z<0.262) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey (HERUS). Some OH119 profiles display a clear P-Cygni shape and therefore imply outflowing OH gas, other profiles are predominantly in absorption or are completely in emission. We find that the relative strength of the OH emission component decreases as the silicate absorption increases. This locates the OH outflows inside the obscured nuclei. The maximum outflow velocities for our sources range from less than 100 to ∼2000 km s −1 , with 15/24 (10/24) sources showing OH absorption at velocities exceeding 700 km s −1 (1000 km s −1 ). Three sources show maximum OH outflow velocities exceeding that of Mrk231. Since outflow velocities above 500-700 km s −1 are thought to require an active galactic nucleus (AGN) to drive them, about 2/3 of our ULIRG sample may host AGN-driven molecular outflows. This finding is supported by the correlation we find between the maximum OH outflow velocity and the IR-derived bolometric AGN luminosity. No such correlation is found with the IR-derived star formation rate. The highest outflow velocities are found among sources which are still deeply embedded. We speculate that the molecular outflows in these sources may be in an early phase of disrupting the nuclear dust veil before these sources evolve into less obscured AGN. Four of our sources show high-velocity wings in their [C II] fine-structure line profiles implying neutral gas outflow masses of at least 2-4.5×10 8 M ⊙ .

We present the first complete ∼55−671 μm spectral scan of a low-mass Class 0 protostar (Serpens SMM1) taken with the PACS and SPIRE spectrometers onboard Herschel. More than 145 lines have been detected, most of them rotationally excited lines of 12 CO (full ladder from J u = 4−3 to 42−41 and E u /k = 4971 K), H 2 O (up to 8 18 −7 07 and E u /k = 1036 K), OH (up to 2 Π 1/2 J = 7/2−5/2 and E u /k = 618 K), 13

The ρ Oph molecular cloud is undergoing intermediate‐mass star formation. Ultraviolet radiation from its hottest young stars heats and dissociates exposed layers, but does not ionize hydrogen. Only faint radiation from the Rayleigh‐Jeans tail of ∼10–100 K dust is expected at wavelengths longwards of ∼3 mm. Yet cosmic background imager (CBI) observations reveal that the ρ Oph W photodissociation region is surprisingly bright at centimetre wavelengths. We searched for interpretations consistent with the Wilkinson Microwave Anisotropy Probe radio spectrum, new Infrared Space Observatory‐Long Wavelength Spectrograph (LWS) parallel mode images and archival Spitzer data. Dust‐related emission mechanisms at 1 cm, as proposed by Draine & Lazarian, are a possibility. But a magnetic enhancement of the grain opacity at 1 cm is inconsistent with the morphology of the dust column maps Nd and the lack of detected polarization. Spinning dust, or electric‐dipole radiation from spinning very small grains (VSGs), comfortably explains the radio spectrum, although not the conspicuous absence from the CBI data of the infrared circumstellar nebulae around the B‐type stars S1 and SR3. Allowing for VSG depletion can marginally reconcile spinning dust with the data. As an alternative interpretation, we consider the continuum from residual charges in ρ Oph W, where most of carbon should be photoionized by the close binary HD 147889 (B2IV, B3IV). Electron densities of ∼102 cm−3, or H‐nucleus densities nH > 106 cm−3, are required to interpret ρ Oph W as the C ii Strömgren sphere of HD 147889. However, the observed steep and positive low‐frequency spectral index would then imply optically thick emission from an hitherto unobserved ensemble of dense clumps or sheets with a filling factor of ∼10−4 and nH∼ 107 cm−3.