Recent content by tosv

Homework Statement I'm working on a project to find evolution equations for a cosmological model, where the following propagations equations are known, \dot{\mu}=-\Theta\mu \dot{\Theta}=-\frac{1}{3}\Theta^{2}-2\sigma^{2}-\frac{1}{2}\mu...

Thanks for your replies! I think my question have been answered now.

What kind of observation can be made to verify the existence of cosmic dust (space dust)?

I have understand that the Parallax method can be used to measure the distance to stars, but what happens when the parallax angle gets to small to be measures accurate? What kind of methods are used to measure distance to star that are like 5000 light years away, or to Superclusters that are...

What is the main reason why there are so many more stars in the Main sequence in comparison with the number of red giants?

Thanks for your reply! I think it makes more sense than my own interpretation, because the surface cannot reflect more light than it receive from the source. It is more probable that the scaling factor would be 4/5. Instead of my previous expression I should use F=\frac{4}{5}\cdot...

Homework Statement I have made a solution to an exercise and I need some to check it and please notify me if I have made any misstakes. Exercise A satellite that is a black body, spherical and rotates around its own axis is send towards the Sun. How far will the satellite reach before its...

Homework Statement I have made a solution to an exercise and I need some to check it and please notify me if I have made any misstakes. Exercise Calculate the radiation flux density of the surface of Earth from the sunlight that is reflected against the surface of Mars. As seen from the...

Thanks for your reply, now I was able to solve the problem. Thanks for your advice, I'll keep it in mind.

Homework Statement Expansion of the universe is described by the scale factor R(t), where t is the time after the Big Bang. For a flat universe the scale factor is today R(t)=C_{1}\cdot t^{\frac{2}{3}} When the Universe was radiation dominated, for t <200,000 years, the scale factor was...

I rewrite the centripetal force as: F_{c}=m\cdot \omega^{2}\cdot r So now I can express the equality between the gravitational force and centripetal force for respective star to be M\omega^{2}R=G\frac{Mm}{(R+r)^{2}} m\omega^{2}r=G\frac{Mm}{(R+r)^{2}} I simply the expression and then and I...

Homework Statement A double star located at a distance of 10 light years from us. The maximum angle between the stars, as seen from Earth, is 2 arcseconds. (1 arcsecond = 1 / 3600 degrees), we can assume that the stellar orbit is circular and that this angle gives us the real distance between...