KH 15D: Gradual Occultation of a Pre–Main-Sequence Binary

We propose that the extraordinary “winking star” KH 15D is an eccentric pre–mainsequence binary that is gradually being occulted by an opaque screen. This model accounts for the periodicity, depth, duration, and rate of growth of the modern eclipses; the historical light curve from photographic plates; and the existing radial velocity measurements. It also explains the re-brightening events that were previously observed during eclipses, and the subsequent disappearance of these events. We predict the future evolution of the system and its full radial velocity curve. Given the small velocity of the occulting screen relative to the center of mass of the binary, the screen is probably associated with the binary, and may be the edge of a precessing circumbinary disk. Subject headings: stars: pre–main-sequence — stars: individual (KH 15D) — circumstellar matter — open clusters and associations: individual (NGC 2264)