Molecular gas associated with the IRAS-Vela shell

We present a survey of molecular gas in the J = 1 -> 0 transition of 12CO towards the IRAS Vela shell. The shell, previously identified from IRAS maps, is a ring-like structure seen in the region of the Gum Nebula. We confirm the presence of molecular gas associated with some of the infrared point sources seen along the Shell. We have studied the morphology and kinematics of the gas and conclude that the shell is expanding at the rate of ~ 13 km/s from a common center. We go on to include in this study the Southern Dark Clouds seen in the region. The distribution and motion of these objects firmly identify them as being part of the shell of molecular gas. Estimates of the mass of gas involved in this expansion reveal that the shell is a massive object comparable to a GMC. From the expansion and various other signatures like the presence of bright-rimmed clouds with head-tail morphology, clumpy distribution of the gas etc., we conjecture that the molecular gas we have detected is the remnant of a GMC in the process of being disrupted and swept outwards through the influence of a central OB association, itself born of the parent cloud.Comment: 21 pages, 9 figures. Figure 1 is a separate jpeg file. To appear in Journal of Astrophysics and Astronom

Flow of fluids with pressure- and shear-dependent viscosity down an inclined plane

In this paper we consider a fluid whose viscosity depends on both the mean normal stress and the shear rate flowing down an inclined plane. Such flows have relevance to geophysical flows. In order to make the problem amenable to analysis, we consider a generalization of the lubrication approximation for the flows of such fluids based on the development of the generalization of the Reynolds equation for such flows. This allows us to obtain analytical solutions to the problem of propagation of waves in a fluid flowing down an inclined plane. We find that the dependence of the viscosity on the pressure can increase the breaking time by an order of magnitude or more than that for the classical Newtonian fluid. In the viscous regime, we find both upslope and downslope travelling wave solutions, and these solutions are quantitatively and qualitatively different from the classical Newtonian solutions

Development of three dimensional constitutive theories based on lower dimensional experimental data

Most three dimensional constitutive relations that have been developed to describe the behavior of bodies are correlated against one dimensional and two dimensional experiments. What is usually lost sight of is the fact that infinity of such three dimensional models may be able to explain these experiments that are lower dimensional. Recently, the notion of maximization of the rate of entropy production has been used to obtain constitutive relations based on the choice of the stored energy and rate of entropy production, etc. In this paper we show different choices for the manner in which the body stores energy and dissipates energy and satisfies the requirement of maximization of the rate of entropy production that leads to many three dimensional models. All of these models, in one dimension, reduce to the model proposed by Burgers to describe the viscoelastic behavior of bodies.Comment: 23 pages, 6 figure

The interstellar clouds of Adams and Blaauw revisited: an HI absorption study - I

This investigation is aimed at clarifying the nature of the interstellar gas seen in absorption against bright O and B stars. Towards this end we have obtained for the first time HI absorption spectra towards radio sources very close to the lines of sight towards 25 bright stars previously studied. In this paper we describe the selection criteria, the details regarding our observations, and finally present the absorption spectra. In the accompanying paper we analyse the results and draw conclusions.Comment: 20 pages, 12 figures, accepted by Journal of Astrophysics and Astronom

Magnetic vortex in color-flavor locked quark matter

Within Ginzburg-Landau theory, we study the structure of a magnetic vortex in color-flavor locked quark matter. This vortex is characterized by winding of the SU(3) phase in color-flavor space, as well as by the presence of a color-flavor unlocked condensate in the core. We estimate the upper and lower critical fields and the critical Ginzburg-Landau parameter that distinguishes between type I and type II superconductors.Comment: 8 pages, 1 figur

Broken-symmetry-adapted Green function theory of condensed matter systems:towards a vector spin-density-functional theory

The group theory framework developed by Fukutome for a systematic analysis of the various broken symmetry types of Hartree-Fock solutions exhibiting spin structures is here extended to the general many body context using spinor-Green function formalism for describing magnetic systems. Consequences of this theory are discussed for examining the magnetism of itinerant electrons in nanometric systems of current interest as well as bulk systems where a vector spin-density form is required, by specializing our work to spin-density-functional formalism. We also formulate the linear response theory for such a system and compare and contrast them with the recent results obtained for localized electron systems. The various phenomenological treatments of itinerant magnetic systems are here unified in this group-theoretical description.Comment: 17 page