The effect of optically thin radiative cooling on the Kelvin-Helmholtz instability of three dimensional jets is investigated via linear stability theory and nonlinear hydrodynamical simulation. Two different cooling functions are considered: radiative cooling is found to have a significant effect on the stability of the jet in each case. The wavelengths and growth rates of unstable modes in the...

We discuss the possibility that gaseous giant planets drive strong outflows during early phases of their formation. We consider the range of parameters appropriate for magneto-centrifugally driven stellar and disk outflow models and find that if the proto-Jovian planet or accretion disk had a magnetic field of ∼> 10 Gauss and moderate mass inflow accretion rates through the disk of less than ∼ ...

We here present the first results of fully three-dimensional (3-D) MHD simulations of radiative cooling pulsed (time-variable) jets for a set of parameters which are suitable for protostellar outflows. Considering different initial magnetic field topologies in approximate equipartition with the thermal gas, i.e., (i) a longitudinal, and (ii) a helical field, both of which permeating the jet and...

We report the discovery, by the Chandra X-ray Observatory, of X-ray emission from the bipolar planetary nebula Menzel 3. In Chandra CCD imaging, Mz 3 displays hot (∼ 3 − 6 × 10 K) gas within its twin, coaxial bubbles of optical nebulosity, as well as a compact X-ray source at the position of its central star(s). The brightest diffuse X-ray emission lies along the polar axis of the optical nebul...

We present interferometric observations in the CO(2–1) line and at 1.3mm dust continuum of the low-mass protostellar binary system in the cometary globule CG30, using the Submillimeter Array. The dust continuum images resolve two compact sources (CG30N and CG30S), with a linear separation of∼ 8700AU and total gas masses of∼ 1.4 and∼ 0.6M⊙, respectively. With the CO images, we discover two high-...

Fast outflows of gas, driven by the interaction between the radio jets and interstellar medium (ISM) of the host galaxy, are being observed in an increasing number of galaxies. One such example is the nearby radio galaxy 3C 293. In this paper we present integral field unit observations taken with OASIS on the William Herschel Telescope, enabling us to map the spatial extent of the ionized gas o...

We have done a statistical analysis of Very Long Baseline Array (VLBA) data of water masers in the star-forming regions (SFRs) Cepheus A and W75 N, using correlation functions to study the spatial clustering and Doppler-velocity distribution of these masers. Two-point spatial correlation functions show a characteristic scale size for clusters of water maser spots .1 AU, similar to the values fo...

We present new 7 mm and archive 1.3 cm high angular resolution observations of the HL/XZ Tau region made with the VLA. At 7 mm, the emission from HL Tau seems to be arising in a clumpy disk with radius of order 25 AU. The 1.3 cm emission from XZ Tau shows the emission from a binary system with 0.3 (42 AU) separation, known from previous optical/IR observations. However, at 7 mm, the southern ra...

We present new narrow-band near-infrared images together with K band spectra of highly collimated bipolar jets close to the IRAS 05487+0255 source. The jets are located at ∼ 50 West of the Herbig-Haro 110 outflow. The jets are not visible at optical wavelengths, and therefore, do not fall into the ‘standard’ Herbig-Haro object classification scheme. Nevertheless, they belong to an ever growing ...

We present images of the HH 211 molecular jet in the SiO v=0, J=1–0 line at 43 GHz made with the Very Large Array at approximately 0.5 arcsec resolution. The SiO emission appears to trace primarily internal bowshocks in the outflow, suggesting that the dust and molecular gas are accelerated via prompt entrainment at internal working surfaces in the jet. There is also some evidence for limb-brig...