First 3D morpho-kinematic model of supernova remnants. The case of VRO 42.05.01 (G166.0+4.3)

ABSTRACT We present the first three-dimensional (3D) morpho-kinematic (MK) model of a supernova remnant (SNR), using as a case study the Galactic SNR VRO 42.05.01. We employed the astrophysical code SHAPE in which wide field imaging and high-resolution spectroscopic data were utilized, to reconstruct its 3D morphology and kinematics. We found that the remnant consists of three basic distinctive components that we call: a ‘shell’, a ‘wing’, and a ‘hat’. With respect to their kinematical behaviour, we found that the ‘wing’ and the ‘shell’ have similar expansion velocities (Vexp = 115 ± 5 km s−1). The ‘hat’ presents the lowest expansion velocity of the remnant (Vexp = 90 ± 20 km s−1), while the upper part of the ‘shell’ presents the highest velocity with respect to the rest of the remnant (Vexp = 155 ± 15 km s−1). Furthermore, the whole nebula has an inclination of ∼3°–5° with respect to the plane of the sky and a systemic velocity of Vsys = −17 ± 3 km s−1. We discuss the interpretation of our model results regarding the origin and evolution of the SNR and we suggest that VRO 42.05.01 had an interaction history with an inhomogeneous ambient medium most likely shaped by the mass outflows of its progenitor star.

5-Axis Flank Milling Tool Path Smoothing Based on Kinematical Behaviour Analysis

In the context of 5-axis flank milling, the machining of non-developable ruled surfaces may lead to complex tool paths to minimize undercut and overcut. The curvature characteristics of these tool paths generate slowdowns affecting the machining time and the quality of the machined surface. The tool path has to be as smooth as possible while respecting the maximum allowed tolerance. In this paper, an iterative approach is proposed to smooth an initial tool path. An indicator of the maximum feedrate is computed using the kinematical constraints of the considered machine tool, especially the maximum velocity, acceleration and jerk. Then, joint coordinates of the tool path are locally smoothed in order to raise the effective feedrate in the area of interest. Machining simulation based on a N-buffer algorithm is used to control undercut and overcut. This method has been tested in flank milling of an impeller and can be applied in 3 to 5-axis machining.

FSI-Analysis of the MMC-Thixoforging Process Regarding the Rheology of the Aluminiumcast-Alloy AlSi7Mg0,3

This paper illustrates investigations regarding the infiltration process of the thixotropic cast-alloy AlSi7Mg0,3 into laminated fibre woven fabrics by Fluid-Structure Interaction Analysis (FSI). As results of such FSI-Analysis on the one hand the kinematical behaviour of the reinforcement due to the infiltration process on the macroscopic and microscopic level on the other hand fluiddynamical effects of the regarded alloy are achieved. Thus in the run-up to timeconsuming and cost-intensive experiments, informative bases like fluidic optimizing of the cavity or the configuration and insertion of the reinforcement component can be numerically developed. Furthermore a reliable prediction of transient permeability of the fibre fabric is possible, which effects the infiltration process significantly. Numerical input data such as rheological parameters characterizing the behaviour of partial solidified alloys have been conducted. Therefor basic rheological tests of the aluminium cast-alloy AlSi7Mg0,3, like `HYSTERESIS TESTS´, `SHEAR RATE JUMP TESTS´ and detection of `STATIC´ and `DYNAMIC YIELD POINTS´ and the `DIFFERENTIAL STRUCTURAL PARAMETER´ have been conducted. Furthermore `EVOLUTION OF VISCOSITY´ has been correlated with thermodynamical calculations using ThermoCalc®. Finally the infiltration of a textile semi-finished part (carbon fibre fabric / canvas bonding) by A356 is discussed as an example to demonstrate the feasibility of FSI-Analysis, taking into account a two-way coupling between the interacting CSM- and CFD-Codes.

Kinematical Study of Old HII Regions and Optical Counterpart to the DRAO Canadian Galactic Plane Survey

This project aims to tackle a few unresolved problems related to the interstellar medium (ISM) by acting as an optical counterpart to the Canadian Galactic Plane Survey (CGPS). We have three main objectives: (1) the study of large/old HII regions; (2) observations of targets-of-opportunity that may be found by the CGPS; (3) comparison of the kinematics of extragalactic (M33) and galactic HII regions. (1) Old HII regions having large spatial extents will be observed to establish their kinematical structure when almost no molecular material is left to produce photodissociated flows. Does turbulence play a role in these objects as for younger nebulae? (2) Ionised nebulae observed by the CGPS that are peculiar, either morphologically or by special association with neutral hydrogen, will also be observed. (3) The kinematical behaviour of old HII regions in M33 will be compared with that of galactic HII regions. With both data sets in hand we will check if HII regions, like supernovae, dump energy into the neutral ISM. The instrument used as well as some very preliminary data are presented.

Gravitational Separation of Elements During Certain Stages of Galactic Evolution

Heavy metal content is, apart from the kinematical behaviour, one of the important parameters of the population characteristics of stars. Spectroscopic observations of some galaxies including our own give the evidence for the gradient of heavy elements abundances towards the galactic center and the galactic plane (Peimbert 1975, Van den Bergh 1975 review papers). Simultaneously several authors (Kuroczkin 1974, Khokhlova 1976) found that the deficiency (or enrichment) increase with the mass number of the element.

Photometry of the Cometary Atmosphere: A Review

Photometry and polarimetry of the cometary heads still constitute one of the most important sources of information about the physical processes in comets. For instance, most of the present estimates of molecular lifetimes are based on the observed distribution of molecules in the cometary head and the assumption of a particular kinematical behaviour of the matter in the cometary atmospheres.The study of kinematics and dynamics of cometary heads and tails has been based upon the analysis of the forms and apparent motions of well-defined envelopes, halos, knots in tails and streams. Direct inspection of a large number of photographs (or drawings from the last century) of several bright comets demonstrates that the cometary head is generally a complicated object. The heads consist of nearly circular diffuse patterns with superposition of different features, particularly of curved streams. This is illustrated by the Atlas of the Cometary Forms compiled by Rahe, Donn and Wurm (1970).