Seeing Through the Ring: Near-infrared Photometry of V582 Mon (KH 15D)

We examine the light and color evolution of the T Tauri binary KH 15D through photometry obtained at wavelengths between 0.55 and 8.0 μm. The data were collected with A Novel Dual Imaging CAMera (ANDICAM) on the 1.3 m SMARTS telescope at Cerro-Tololo Inter-American Observatory and with InfraRed Array Camera on the Spitzer Space Telescope. We show that the system's circumbinary ring, which acts as a screen that covers and uncovers different portions of the binary orbit as the ring precesses, has reached an orientation where the brighter component (star B) fully or nearly fully emerges during each orbital cycle. The fainter component (star A) remains fully occulted by the screen at all phases. The leading and trailing edges of the screen move across the sky at the same rate of ~15 m s^(−1), consistent with expectation for a ring with a radius and width of ~4 au and a precession period of ~6500 years. Light and color variations continue to indicate that the screen is sharp edged and opaque at VRIJH wavelengths. However, we find an increasing transparency of the ring edge at 2.2, 3.6, and 4.5 μm. Reddening seen at the beginning of the eclipse that occurred during the CSI 2264 campaign particularly suggests selective extinction by a population of large dust grains. Meanwhile, the gradual bluing observed while star B is setting is indicative of forward scattering effects at the edge of the ring. The spectral energy distribution of the system at its bright phase shows no evidence of infrared excess emission that can be attributed to radiation from the ring or other dust component out to 8 μm

Characterizing Eclipsing Binaries and the Population of Planets Orbiting Around Them

Thesis (Ph.D.)--University of Washington, 2020The majority of main sequence (MS) and pre-MS (PMS) stars reside in binaries or hierarchical multiples (Abt 1979; Duchêne & Kraus 2013). Understanding planetary processes and regimes of habitability in a general framework requires statistical studies of planets around all modes of stellar multiplicity. This thesis aims to constrain the demographics of planets orbiting binary stars (circumbinary planets; CBPs), using an independent, automated detection pipeline analysis. To do this, I exploit high cadence & high precision photometry and the transiting geometry to measure physical properties of eclipsing binaries (EBs) and detect CBPs around them. In particular, I create a modular eclipsing binary modeling code which leverages stellar evolution models with time-series, multi-band, and positional photometry to extract full system parameters, including stellar mass. This technique enables mass estimation for large ensembles of EBs, accurate to within 10% for detached MS systems, and I apply it to assemble a Bayesian catalogue of 728 fully characterized Kepler EBs. Next, I develop a hybrid transit detection method that is robust to large transit timing and duration variations associated with transiting CBPs. It corrects for large scale variations induced by binary reflex motion using a physical CBP model, and subsequently employs the Quasi-periodic Automated Transit Search algorithm (QATS; Carter & Agol 2013) to empirically treat additional aperiodicities, due to model inaccuracies and assumptions. This dual accounting for quasi-periodicity improves CBP detection significance, by greater than a factor of 2 from previous efforts. Finally, I apply a CBP transit search on the Kepler EB subsample with full system solutions, and detect 8 robust candidates (corresponding to previously by-eye discovered CBPs) and 4 marginal candidates. Reconciling the detected CBP candidates with a thorough audit of detection and selection biases, I infer population-level trends for CBPs and contextualize my findings with complementary detection results, formation theories, as well as important directions for the future

SEEING THROUGH THE RING: NEAR-INFRARED PHOTOMETRY OF V582 MON (KH 15D)

We examine the light and color evolution of the T Tauri binary KH 15D through photometry obtained at wavelengths between 0.55 and 8.0 μm. The data were collected with A Novel Dual Imaging CAMera (ANDICAM) on the 1.3 m SMARTS telescope at Cerro-Tololo Inter-American Observatory and with InfraRed Array Camera on the Spitzer Space Telescope. We show that the system's circumbinary ring, which acts as a screen that covers and uncovers different portions of the binary orbit as the ring precesses, has reached an orientation where the brighter component (star B) fully or nearly fully emerges during each orbital cycle. The fainter component (star A) remains fully occulted by the screen at all phases. The leading and trailing edges of the screen move across the sky at the same rate of ~15 m s[superscript −1], consistent with expectation for a ring with a radius and width of ~4 au and a precession period of ~6500 years. Light and color variations continue to indicate that the screen is sharp edged and opaque at VRIJH wavelengths. However, we find an increasing transparency of the ring edge at 2.2, 3.6, and 4.5 μm. Reddening seen at the beginning of the eclipse that occurred during the CSI 2264 campaign particularly suggests selective extinction by a population of large dust grains. Meanwhile, the gradual bluing observed while star B is setting is indicative of forward scattering effects at the edge of the ring. The spectral energy distribution of the system at its bright phase shows no evidence of infrared excess emission that can be attributed to radiation from the ring or other dust component out to 8 μm