Apsidal vectors

[ehrenfest]

Homework Statement

My classical mechanics book (Goldstein) talks about apsidal vectors in the context of central force problems and elliptical orbits. I cannot find where the book defines this term and it is nowhere on the internet. Has anyone heard this term before?

Homework Equations

The Attempt at a Solution

 

[dynamicsolo]

Homework Statement

My classical mechanics book (Goldstein) talks about apsidal vectors in the context of central force problems and elliptical orbits. I cannot find where the book defines this term and it is nowhere on the internet. Has anyone heard this term before?

The line of apsides for an elliptical orbit joins the pericenter and apocenter of the orbit, i.e., it is the major axis. For open trajectories (parabolas and hyperbolas), it would still be the symmetry axis of the orbit. The eccentricity vector e, for example, has the magnitude of the eccentricity and points from the occupied focus to the pericenter. Here's a place to start: http://en.wikipedia.org/wiki/Apse_line ; Googling "apsidal vector" produces an avalanche, as does "line of apsides", but there are sites and books on the Web of some help. Celestial mechanics texts may also be useful to you.