We present a study of dense molecular gas kinematics in seventeen nearby protostellar systems using single-dish and interferometric molecular line observations. The non-axisymmetric envelopes around a sample of Class 0/I protostars were mapped in the N 2 H + (J = 1 → 0) tracer with the IRAM 30m, CARMA and PdBI as well as NH 3 (1,1) with the VLA. The molecular line emission is used to construct line-center velocity and linewidth maps for all sources to examine the kinematic structure in the envelopes on spatial scales from 0.1 pc to ∼1000 AU. The direction of the large-scale velocity gradients from single-dish mapping is within 45 • of normal to the outflow axis in more than half the sample. Furthermore, the velocity gradients are often quite substantial, the average being ∼2.3 km s −1 pc −1 . The interferometric data often reveal small-scale velocity structure, departing from the more gradual large-scale velocity gradients. In some cases, this likely indicates accelerating infall and/or rotational spin-up in the inner envelope; the median velocity gradient from the interferometric data is ∼10.7 km s −1 pc −1 . In two systems, we detect high-velocity HCO + (J = 1 → 0) emission inside the highestvelocity N 2 H + emission. This enables us to study the infall and rotation close to the disk and estimate the central object masses. The velocity fields observed on large and small-scales are more complex than would be expected from rotation alone, suggesting that complex envelope structure enables other dynamical processes (i.e. infall) to affect the velocity field. 1 Based on observations carried out with the IRAM 30m Telescope and IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).-5with 20kHz channels and in 2009 we used 40 MHz with 20kHz channels; see Table 2 the list of sources observed and more detail.We conducted our observations using frequency-switched on-the-fly (OTF) mapping mode. The maps varied in size depending on the extent of the source being observed, most being 3 × 3 . Most maps were integrated down to at least σ T ∼ 150mK for the N 2 H + (J = 1 → 0) transition, noise levels for each map are listed in Table 2. We mapped the sources by scanning in the northsouth direction and again in the east-west direction to minimize striping in the final map. The scan legs were stepped by 5 and we repeated the maps to gain a higher signal-to-noise ratio. Calibration scans were taken about every 10 minutes between scan legs and the final maps took approximately 2 hours to complete. Pointing was checked about every two hours, azimuth and elevation offsets were typically ±5 ; the pointing offset remained stable, typically within ∼2 during an observation. These values agree well with the rms pointing accuracy of ∼2 .

The Pipe nebula is a massive, nearby, filamentary dark molecular cloud with a low star-formation efficiency threaded by a uniform magnetic field perpendicular to its main axis. It harbors more than a hundred, mostly quiescent, very chemically young starless cores. The cloud is, therefore, a good laboratory to study the earliest stages of the star-formation process. We aim to investigate the primordial conditions and the relation among physical, chemical, and magnetic properties in the evolution of low-mass starless cores. We used the IRAM 30-m telescope to map the 1.2 mm dust continuum emission of five new starless cores, which are in good agreement with previous visual extinction maps. For the sample of nine cores, which includes the four cores studied in a previous work, we derived a A V to N H 2 factor of (1.27±0.12)×10 −21 mag cm 2 and a background visual extinction of ∼6.7 mag possibly arising from the cloud material. We derived an average core diameter of ∼0.08 pc, density of ∼10 5 cm −3 , and mass of ∼1.7 M ⊙ . Several trends seem to exist related to increasing core density: (i) diameter seems to shrink, (ii) mass seems to increase, and (iii) chemistry tends to be richer. No correlation is found between the direction of the surrounding diffuse medium magnetic field and the projected orientation of the cores, suggesting that large scale magnetic fields seem to play a secondary role in shaping the cores. We also used the IRAM 30-m telescope to extend the previous molecular survey at 1 and 3 mm of earlyand late-time molecules toward the same five new Pipe nebula starless cores, and analyzed the normalized intensities of the detected molecular transitions. We confirmed the chemical differentiation toward the sample and increased the number of molecular transitions of the "diffuse" (e.g. the "ubiquitous" CO, C 2 H, and CS), "oxo-sulfurated" (e.g. SO and CH 3 OH), and "deuterated" (e.g. N 2 H + , CN, and HCN) starless core groups. The chemically defined core groups seem to be related to different evolutionary stages: "diffuse" cores present the cloud chemistry and are the less dense, while "deuterated" cores are the densest and present a chemistry typical of evolved dense cores. "Oxo-sulfurated" cores might be in a transitional stage exhibiting intermediate properties and a very characteristic chemistry.

We present 6 and 20 cm JVLA/VLA observations of the northern head of the HH 80/81/80N jet, one of the largest collimated jet systems known so far, aimed to look for knots further away than HH 80N, the northern head of the jet. Aligned with the jet and 10 northeast of HH 80N, we found a radio source not reported before, with a negative spectral index similar to that HH 80, HH 81 and HH 80N. The fit of a precessing jet model to the knots of the HH 80/81/80N jet, including the new source, shows that the position of this source is close to the jet path resulting from the modeling. If the new source belongs to the HH 80/81/80N jet, its derived size and dynamical age are 18.4 pc and > 9 × 10 3 yr, respectively. If the jet is symmetric, its southern lobe would expand beyond the cloud edge resulting in an asymmetric appearance of the jet. Based on the updated dynamical age, we speculate on the possibility that the HH 80/81/80N jet triggered the star formation observed in a dense core found ahead of HH 80N, which shows signposts of interaction with the jet. These results indicate that pc scale radio jets can play a role on the stability of dense clumps and the regulation of star formation in the molecular cloud.

The radio-knots of the HH 80/81/80N jet extends from the HH 80 object to the recently discovered Source 34 and has a total projected jet size of 10.3 pc, constituting the largest collimated radio-jet system known so far. It is powered by the bright infrared source IRAS 18162−2048 associated with a massive young stellar object. We report 6 cm JVLA observations that, compared with previous 6 cm VLA observations carried out in 1989, allow us to derive proper motions of the HH 80, HH 81 and HH 80N radio knots located about 2.5 pc away in projection from the powering source. For the first time, we measure proper motions of the optically obscured HH 80N object providing evidence that this knot, along with HH 81 and HH 80 are associated with the same radio-jet. We also confirm the presence of Source 34, located further north of HH 80N, previously proposed to belong to the jet. We derived that the tangential velocity of HH 80N is 260 km s −1 and has a direction in agreement with the expected direction of a ballistic precessing jet. The HH 80 and HH 81 objects have tangential velocities of 350 and 220 km s −1 , respectively, but their directions are somewhat deviated from the expected jet path. The velocities of the HH objects studied in this work are significantly lower than those derived for the radio knots of the jet close to the powering source (600-1400 km s −1 ) suggesting that the jet is slowing down due to a strong interaction with the ambient medium. As a result, since HH -2 -80 and HH 81 are located near the edge of the cloud, the inhomogeneous and low density medium may contribute to skew the direction of their determined proper motions. The HH 80 and HH 80N emission at 6 cm is, at least in part, probably synchrotron radiation produced by relativistic electrons in a magnetic field of 1 mG. If these electrons are accelerated in a reverse adiabatic shock, we estimate a jet total density of 1000 cm −3 . All these features are consistent with a jet emanating from a high mass protostar and make evident its capability of accelerating particles up to relativistic velocities.