We present an analytic model of a collimated ejection with a “single pulse” Gaussian ejection velocity. This flow produces a dense “head” (the leading working surface) joined to the outflow source by a “tail” of lower velocity material. For times greater than the duration of the ejection pulse, this tail develops a linear radial velocity vs. position structure. This “head/tail plasmon” structure is interesting for modelling astrophysical “bullets” joined to their outflow sources by structures with “Hubble law” radial velocity dependencies. We study the case of a Gaussian ejection velocity law with a constant and a Gaussian ejection density history, We compare these two cases, and find that the main effect of the different ejection density histories is to change the mass and the density stratification of the plasmon tail.

We present a new plasmon model for a cometary clump moving supersonically in an environment with a non-zero gas pressure. We find that the environmental pressure produces a cutoff in the wings of the cometary clump, therefore resulting in quite "stubby" plasmons for a large range of flow Mach numbers. We derive a relation between the length-to-width ratio of the plasmon and the Mach number M of the flow, which could be used to directly derive M from observations of (appropriate) cometary clumps.

GUIELOA is a Curvature type Adaptive Optics system for the 2.1 m San Pedro Mártir Telescope. It performs a bimorph 19 actuators deformable mirror and a 19 lens-let array for the wave-front sensor (WFS). GUIELOA corrects effectively the first 8 Zernike polynomials of the aberrated wave-front produced by the atmospheric turbulence. For the closed loop control it performs two SPARC FORCE 5 SBC computers working in concert. The lens-let array + optical fibers send the light from defocused pupil images to 19 avalanche photo-diodes. In this work it is shown how the lens-let array was manufactured at IAUNAM with CIDESI and Centro de Investigaciones en Optica (CIO).

Recent observations in radio, infrared and visible wavelengths have revealed the presence of small, elongated gaseous structures that appear to emanate from young stars. These structures are frequently interpreted as jets, perhaps similar in nature to those observed in extragalactic objects. We argue that these apparent “jets” could simply be light emitted by, or reflected from the walls of the cavities expected to be formed when the winds of these young stars drive their surrounding gaseous medium away. When viewed from certain positions the radiation from the walls of these cavities appears to the observer as elongated structures. A simple model is presented to illustrate this projection effect.