Constraining the Circumbinary Disk Tilt in the KH 15D system

Abstract: KH 15D is a system which consists of a young, eccentric binary, and a circumbinary disk which obscures the binary as the disk precesses. We develop a self-consistent model that provides a reasonable fit to the photometric variability that was observed in the KH 15D system over the past 60 years. Our model suggests that the circumbinary disk has an inner edge $r_{\rm in}\lesssim 1 \ {\rm au}$, an outer edge $r_{\rm out} \sim {\rm a \ few \ au}$, and that the disk is misaligned relative to the stellar binary by $\sim$5-16 degrees, with the inner edge more inclined than the outer edge. The difference between the inclinations (warp) and longitude of ascending nodes (twist) at the inner and outer edges of the disk are of order $\sim$10 degrees and $\sim$15 degrees, respectively. We also provide constraints on other properties of the disk, such as the precession period and surface density profile. Our work demonstrates the power of photometric data in constraining the physical properties of planet-forming circumbinary disks.