Locating the Trailing Edge of the Circumbinary Ring in the KH 15D System

Abstract

Following two years of complete occultation of both stars by its opaque circumbinary ring, the binary T Tauri star KH 15D has abruptly brightened again during apastron phases, reaching I = 15 mag. Here, we show that the brightening is accompanied by a change in spectral class from K6/K7 (the spectral class of star A) to ~K1, and a bluing of the system in V-I by about 0.3 mag. A radial velocity measurement confirms that, at apastron, we are now seeing direct light from star B, which is more luminous and of earlier spectral class than star A. Evidently, the trailing edge of the occulting screen has just become tangent to one anse of star B's projected orbit. This confirms a prediction of the precession models, supports the view that the tilted ring is self-gravitating, and ushers in a new era of the system's evolution that should be accompanied by the same kind of dramatic phenomena observed from 1995-2009. It also promotes KH 15D from a single-lined to a double-lined eclipsing binary, greatly enhancing its value for testing pre-main sequence models. The results of our study strengthen the case for truncation of the outer ring at around 4 AU by a sub-stellar object such as an extremely young giant planet. The system is currently at an optimal configuration for detecting the putative planet and we urge expedient follow-up observations.

6 pages, 5 figures, accepted for publication in ApJ Letters

References in corpus (5)

• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• Redshifted Absorption at He I 10830 as a Probe of the Accretion Geometry of T Tauri Stars
• The Orbit and Occultations of KH 15D
• Reflected Light from Sand Grains in the Terrestrial Zone of a Protoplanetary Disk
• Extending the Model of KH 15D: Estimating the Effects of Forward Scattering and Curvature of the Occulting Ring Edge

Cited by in corpus (29)

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• Linear Analysis of the Evolution of Nearly Polar Low Mass Circumbinary Discs
• Wave-like warp propagation in circumbinary discs II. Application to KH 15D
• Evolution of linear warps in accretion discs and applications to protoplanetary discs in binaries
• Polar alignment of a protoplanetary disc around an eccentric binary II: Effect of binary and disc parameters
• Assembly of Protoplanetary Disks and Inclinations of Circumbinary Planets
• Polar alignment of a protoplanetary disc around an eccentric binary III: Effect of disc mass
• Alignment of a circumbinary disc around an eccentric binary with application to KH 15D
• Polar planets around highly eccentric binaries are the most stable
• Circumbinary disk inner radius as a diagnostic for disk--binary misalignment
• The Architecture of the GW Ori Young Triple Star System and Its Disk: Dynamical Masses, Mutual Inclinations, and Recurrent Eclipses
• The eclipse of the V773 Tau B circumbinary disk
• Constraining the Circumbinary Disk Tilt in the KH 15D system
• Optical and Radio Observations of the T Tauri Binary KH 15D (V582 Mon): Stellar Properties, Disk Mass Limit and Discovery of a CO Outflow
• A radial limit on polar circumbinary orbits from general relativity
• Multi-Wavelength Photometry of the T Tauri Binary V582 Mon (KH 15D): A New Epoch of Occultations
• Two Candidate KH 15D-like Systems from the Zwicky Transient Facility
• Polar alignment of a massive retrograde circumbinary disc around an eccentric binary
• Seeing Through the Ring: Near-Infrared Photometry of V582 Mon (KH 15D)
• Orbital dynamics of two circumbinary planets around misaligned eccentric binaries
• Untangling the Near-IR Spectral Features in the Protoplanetary Environment of KH 15D
• Double-peaked OI profile: a likely signature of the gaseous ring around KH 15D
• Orbital stability of two circumbinary planets around misaligned eccentric binaries
• Excitation of post-AGB Star Binary Eccentricity by Massive Polar-Aligned Circumbinary Disks
• Dynamical Stability of Polar Circumbinary Orbits and Planet-Formation in Planetary Disc of 99 Herculis
• Accretion Kinematics in the T Tauri Binary TWA 3A: Evidence for Preferential Accretion onto the TWA 3A Primary