Week 5: Dynamical Friction

Reading¶

• Section 19.4.1 of Bovy

• Kirsh et al. 2009 “Simulations of planet migration driven by planetesimal scattering”

Reading questions¶

• Explain dynamical friction in a sentence or two.

• Why is the quantity $h(v)$ in equation (19.35) referred to as a ‘‘potential’’? In going from equation (19.35) to (19.36) an upper limit $v_M$ appears on the integral. Why?

• Equation (19.42) gives the timescale for dynamical friction to decay the orbit of a massive body of mass $M$ moving in a cluster of total mass $M_\mathrm{tot}$. If you wanted to evaluate this timescale, how would you evaluate the factors $t_\mathrm{dyn}$ and $\Lambda$?

• What is the main takeaway of the Kirsh et al. paper?

• How would you calculate the location of the inner and outer edges of the feeding zone?

• What is the Hill eccentricity $e_H$ and why is it a useful quantity to look at?

• Explain the different features that can be seen in the $a$-$e_H$ plot in Figure 4.

Answers to these questions should be submitted to your github repository before class on Monday.