LOCATING THE TRAILING EDGE OF THE CIRCUMBINARY RING IN THE KH 15D SYSTEM

Journal Article · Thu Sep 20 04:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/757/1/L18· OSTI ID:22078530

Capelo, Holly L; Herbst, William ^[1]; Leggett, S K ^[2]; Hamilton, Catrina M ^[3]; Johnson, John A ^[4]

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1. Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States)
2. Gemini Observatory, Northern Operations Center, 670 N. A'ohoku Place, Hilo, HI 96720 (United States)
3. Department of Physics and Astronomy, Dickinson College, Carlisle, PA 17013 (United States)
4. Department of Astrophysics, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)

Following two years of complete occultation of both stars in the binary T Tauri star KH 15D by its opaque circumbinary ring, 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 {approx}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 to 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.

• OSTI ID: 22078530
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 757; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ECLIPSE
ORBITS
PLANETS
PRECESSION
RADIAL VELOCITY
STAR EVOLUTION
T TAURI STARS
VISIBLE RADIATION