ASTR221 HW#4 -- Due Oct 21 2005

1. Saturn's Rings

We will make a rough estimate of the mass contained in Saturn's rings. Assume that the rings have a constant mass density and that the rings are 30 meters thick with an inner radius of 1.5 RSaturn and an outer radius of 3 RSaturn. Assume also that the ring particles are water-ice spheres of radius 1 cm and that the optical depth of the rings is unity (i.e., tau=1, so you can just barely see through them).

2. Planetary Accretion

When the solar system first formed, it was characterized by a disk of dust and gas (called the "solar nebula") with some larger planetesimals embedded within it. As these planetesimals orbited in the solar nebula, they continually accreted material from the nebula, slowly growing in size. In this problem, we will estimate how long it took these planetesimals to grow into reasonable sized objects (ie a thousand km or so in size).
where rhoN=the space density (kg/m3) of particles in the cloud and m=the mass of each particle.
where M=the planetesimal mass.

3. Magnitudes and Distances

App Mag
Distance (pc)
Parallax (")
Abs Mag








4. Textbook Problems

(Be careful, the textbook has Questions, Problems, and Computer Problems at the end of each chapter. I am asking for the "Problems", not the "Questions" or "Computer Problems")