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The kinematics and physical conditions of the bipolar planetary nebula M 2-48 are analysed from high and low dispersion long-slit spectra. Previous CCD narrow-band optical observations have suggested that this nebula is mainly formed by a pair of symmetric bowshocks, an off-center semi-circular shell, and an internal bipolar structure. The bipolar outflow(More)
‘Compact’ H II regions (embedded in dense molecular clouds) relax to a pressure equilibrium configuration in shorter time-scales than the main-sequence lifetime of the exciting O stars. This result motivates a rederivation of the analytic model for the expansion of an H II region into a uniform environment. We have modified the classical model so as to(More)
We present a 3D numerical simulation of the recently discovered cometary structure produced as Mira travels through the galactic ISM. In our simulation, we consider that Mira ejects a steady, latitude-dependent wind, which interacts with a homogeneous, streaming environment. The axisymmetry of the problem is broken by the lack of alignment between the(More)
We present synthetic emission maps and long-slit spectra in the [O i]6300 and [S ii]6731 lines for self-similar, cold MHD disk winds of high magnetic torque. We find that such models produce both a dense, compact low-velocity component (LVC) and a lower density, collimated high-velocity component (HVC) sharing several observed properties of jets from T(More)
We have obtained a Hα position-velocity cube from Fabry-Pérot interferometric observations of the HH 110 flow. We analyze the results in terms of anisotropic wavelet transforms, from which we derive the spatial distribution of the knots as well as their characteristic sizes (along and across the outflow axis). We then study the spatial behaviour of the line(More)
We have studied the kinematics traced by the water masers located at the centre of the planetary nebula (PN) K3-35, using data from previous Very Large Array (VLA) observations. An analysis of the spatial distribution and line-of-sight velocities of the maser spots allows us to identify typical patterns of a rotating and expanding ring in the(More)
Most models of radiative jets have been computed for the special case of a top hat initial cross section. This paper discusses the dynamics of both leading and internal working surfaces in jets with more general initial cross sections, based on both an analytic, “thin shell” model, and on a full numerical simulation. We find that a non-top hat cross section(More)
Molecular clouds in the interstellar medium suffer gravitational instabilities that lead to the formation of one or multiple stars. A recently formed star inside a cold cloud communicates its gravitational force to the surrounding environment and soon an accretion flow falling into the star develops. After their formation, all stars soon eject a wind of gas(More)
Neutral clumps immersed in HII regions are frequently found in star formation regions. We investigate here the formation of tail of neutral gas, which are not reached by the direct ionizing flux coming from two massive stars, using both an analytical approximation, that allows us to estimate the shadow geometry behind the clumps for different initial(More)