We study the nonlinear dynamics of a warped or twisted accretion disc, in which the viscosity coefficients are assumed to be locally proportional to the rotational velocity (Beta -prescription). Using asymptotic methods ...

A deep photometric analysis in the open star cluster NGC 1883 has been presented here and added to the work of Carraro et al. (2003), which is the only previous work introduced for this cluster. The radius and metallicity ...

In this thesis we have undertaken a detailed study of the evolution of young circumstellar disks from the early pre-main sequence phase to the main sequence phase. We have used several observational diagnostics of the disks ...

This thesis is on the framework of the "NainiTal-Cape Survey" programme for searching photometric variability in chemically peculiar stars, initiated in 1997 at the ARIES, NainiTal, India, in collaboration with the South ...

Shocks in advective flows around black holes have become es- sential ingredients in explaining wide variety of observed features. We first analytically study the properties of shocks in the special case when viscosity and ...

Modern solar telescope designs are different from the conven- tional concept of vacuum telescopes. These new designs are "open" telescopes which try to minimize the temperature difference between various parts of the ...

Since the advent of the satellite era, X-ray astronomy and UV astronomy have advanced tremendously. The discovery of intense X-ray emission from accreting compact objects has permitted very detailed timing and spectral ...

The 1.2 m Mt. Abu telescope at Gurushikhar is operated by the Astronomy & Astrophysics Division of Physical Research Laboratory, Ahmed- abad. The evolution of the telescope control system to its present form has been ...

The sunlight is scattered by the dust grains present in the coma and tail of comets which makes it visible. The scattered sunlight is characteristically polarized with degree of polarization generally depending upon the ...