http://arxiv.org/abs/1711.08166
In Paper I (Bae & Zhu 2017), we explained how a planet excites multiple spiral arms in a protoplanetary disk. To examine whether various characteristics of observed spiral arms can be used to constrain the masses of unseen planets and their positions within their disks, we carry out two-dimensional simulations varying planet mass and disk gas temperature. A larger number of spiral arms form with a smaller planet mass and a lower disk temperature. For a range of disk temperature characterized by the disk aspect ratio $0.04 \leq (h/r)p \leq 0.15$, three or fewer spiral arms are excited interior to a planet’s orbit when $M_p/M* \gtrsim 3\times10^{-4}$ and two spiral arms when $M_p/M_* \gtrsim 3\times10^{-3}$. Exterior to a planet’s orbit, multiple spiral arms can form only in cold disks with $(h/r)_p \lesssim 0.06$. Constraining the planet mass with the pitch angle of spiral arms requires accurate disk temperature measurements that might be challenging even with ALMA. However, the property that the pitch angle of planet-driven spiral arms decreases away from the planet can be a powerful diagnostic to determine whether the planet is located interior or exterior to the observed spirals. The arm-to-arm separations increase as a function of planet mass, consistent with previous studies; however, we find that the exact slope depends on disk temperature as well as the radial location where the arm-to-arm separations are measured. We apply these diagnostics to the spiral arms seen in MWC 758 and Elias 2-27. Finally, we discuss the possibility that Jupiter’s core creates multiple pressure bumps in the solar nebula through spiral shocks, and show how it can help explain meteoritic properties.
J. Bae and Z. Zhu
Thu, 23 Nov 17
13/52
Comments: 14 pages, 10 figures, Figure 2 size reduced to meet the requirement, submitted to the ApJ