Relativity: a quick introduction 
A quick introduction to Special Relativity with a derivation of E=mc2.
Light-travel time effects in binary systems 
The light-travel time effects for a pulsating star (or a close
binary) in a binary system are calculated.
Mach's Principle and Evolution of the Universe 
Within the framework of Mach's principle and of D.W. Sciama's physical
interpretation of it, a quantitative evaluation of the inertial mass as
a function of the density of the universe and of the epoch is obtained.
The calculation is somewhat similar to the solution of Olbers's paradox.
The result shows that the inertial mass varies as the universe expands
except for a flat, Euclidean universe. This leads to insights on the Principle
Stellar structure 
The equations that describe a polytropic star structure are derived.
Pulsating stars I: Differential equation 
The differential equation of a radially pulsating star is derived.
Pulsating stars II: Solutions at constant density 
The differential equation for a radially pulsating star is solved
for a constant density.
Pulsating stars III: Polytropic model 
The solutions to the differential equation of a radially pulsating
star are presented for a polytropic model.
Binary systems: orbital period and mass transfer 
The equations for the relation between the orbital period change
of a binary system and the mass transfer are explicited.