Theoretical investigation of interstellar C–C–O and C–O–C bonding backbone molecules

There are numerous complex organic molecules containing carbon and oxygen atoms which show either C–C–O or C–O–C bonding backbone. This paper examines altogether 51 C–C–O and C–O–C bonding backbone molecules from ten different isomeric groups (C₂H₂O, C₃H₂O, C₂H₄O, C₂H₄O₂, C₃H₄O, C₂H₆O, C₂H₆O₂, C₃H₆O, C₃H₆O₂, C₃H₈O) to summarize the present astronomical status of these molecules. Accurate calculations of enthalpy of formation of these molecules show that the isomers with C–C–O backbone are more stable than the C–O–C backbone. Interestingly, a detailed analysis of relevant astromolecules indicates that most of the observed astromolecules have the C–C–O backbone. As a matter of fact, of all the molecules examined in this study, 80% of the astronomically observed species have the C–C–O backbone while only 20% have the C–O–C backbone. In general, interstellar abundance of a molecule is controlled by some factors such as kinetics, formation and destruction pathways,thermodynamics etc. A proper consideration of these factors could explain the observed abundances of these molecules. All these possible key factors are discussed in this paper.     

Chronology and sediment provenance of extreme floods of Siang River (Tsangpo-Brahmaputra River valley), northeast Himalaya

This study explores paleoflood deposits of the Siang River, known as the Tsangpo in Tibet. The river that often experiences large floods brings down huge amount of sediment and water that adversely affect the downstream regions with large human populations in the states of northeast Himalaya and its foreland. Along it's ~300 km mountainous stretch we collected samples for sedimentological, petrographic and Sr–Nd isotopic study to explore sediment provenance and dated the paleofloods (via optically stimulated luminescence, OSL). Geomorphic indices including precipitation and a geomorphic swath profile across the Brahmaputra catchment were studied to understand the interplay of mountain relief and rainfall that determine potential zones of high erosion and sediment supply. The OSL technique indicated the Siang River experienced at least eight large floods between 7 and 1 ka, possibly under the influence of warm and wet climatic conditions. The petrographic and isotopic data suggests that the eastern Himalayan syntaxis, which has the highest uplift and exhumation rate in the area, is not always the highest sediment producing zone. In some instances, the Tibetan plateau produces higher fluxes of sediments via glacial and landslide lake outburst floods (GLOFs and LLOFs). © 2020 John Wiley & Sons, Ltd.     

On a uniformly rotating magnetic polytrope

The equilibrium general magnetic field inside a magneto-rotating star, assumed to be a polytrope, has been determined more accurately, for large general magnetic field. Furthermore the effect of such field on the structure and oscillations of a slowly rotating polytrope has been studied forn=1,0, 1.5, 2.0, and 3.0.     

Exact solution of a key equation in a finite planetary atmosphere by the method of laplace transform and linear singular operators

Considering the ground reflection according to Lambert's law, we establish a fundamental equation in finite planetary atmospheres. An exact form of the solution of this equation is obtained for the emergent quantities from the bounding faces in terms ofX-Y equations by the method of Laplace transform, in combination with the theory of linear singular operators.     

An exact solution of transfer equations for interlocked multiplets

The transfer equations for non-coherent scattering arising from interlocking of principal lines without redistribution is exactly solved in a very simple way by Laplace tranform and Wiener-Hopf technique which are easily applied by the use of the new representation ofH-functions obtained recently by the author (1977). The emergent intensity in therth line is expressed in terms of anH-function and a Cauchy type integral admitting of closed form evaluation.     

Generation of ionospheric irregularities by thermal-source: A new mechanism

A new mechanism for the generation of ionospheric irregularities of scale sizes of the order of 100 m or more, has been developed on the basis of thermal energy source due to collisional current dissipation. The important role is played by the diffusion of particles along and across the magnetic field. The threshold condition for the instability has been obtained and it is shown that these irregularities can be generated in the F-region height of auroral ionosphere when the electric field is enhanced to about 10 mV m^?1.     

Nonlinear propagation of whistlers in the ionosphere

In this paper, the nonlinear dispersion relation for whistlers in the ionosphere has been derived and then the group travel time for an ion-cyclotron whistler from its source to an observer at the satellite has been theoretically calculated. It is seen that the nonlinear effect has some important contribution in the expression of group travel time. Our present analysis gives a more correct result than that obtained by Gurnett and others. From numerical estimations, it is found that the group travel time of whistler may be changed reasonably due to nonlinear interaction of the wave and the plasma of ionosphere.