We present the first results of a new type of observational program being carried out using the 2.34m Vainu Bappu Telescope at Kavalur. This program involves intra-night optical monitoring of radio quiet but optically ...

Faint straight arcs extending over ten to twenty arcseconds have been observed behind rich clusters of galaxies elongated by the lensing action of the foreground cluster. When a cluster of galaxies has its projected surface ...

We present a model for an observed gravitationally lensed system, MG2016+112. We assume that there are two galaxies acting as lenses (as suggested by the observations), each with a diffuse dark matter halo. It is shown ...

There are several examples of existence of naked singularities in models of spherically symmetric gravitational collapse and they are considered to be counter-examples to the Cosmic Censorship (CCC). In fact, there were ...

On dark matter, whereas current research is in the field of weakly interacting particles, this work puts forward a different line of approach. It interprets dark matter as a transformation of matter by a generalized ...

The dynamics of cosmic ray ions of energy 10-100 MeV/N in and around the terrestrial magnetic field is studied using the method of trajectory tracing. The trajectory of a cosmic ray particle is back traced from the point ...

The complete 150 kyr record of Be-10 concentration in the Vostok ice core in Antarctica displays several steep and relatively brief increases. Out of these, the increase at approximately 33 Kyr is unique, as this is not ...

The cosmic ray density distribution near earth is generally investigated by using the yearly excursion in the heliographic latitudinal position of earth. The study has been done for 1978 to 1990 to determine the density ...

The work contained in this thesis was carried out at the Physical Research Laboratory, Ahmedabad and describes observations of Interplanetary Scintillation (IPS), carried out since 1984, using a large 10,000 sq m dipole ...

Gravitational fields in clusters as well as the hydrodynamic effects of the intracluster medium on the gas in galaxies are responsible for the observed differences between cluster and field galaxies. The thesis consists ...