HD106906 Debris Disk Morphology and Origin of an External Perturber
Abstract
HD 106906 is a nearby Sun-like binary star system that hosts both an eccentric debris disk and a wide-separation planet. It is the only known system to host a companion that is not only external to, but also dynamically disturbing the debris disk. Studying this system gives us the opportunity learn more about dynamical mechanisms that shape the morphologies of planetary systems. We present 0.5" resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the HD 106906 debris disk at a wavelength of 1.3 mm. We spatially resolve the debris disk at millimeter wavelengths for the first time, and compare it with a dynamical model of the parent body distribution based on an in situ formation scenario presented in Nesvold et al. (2017). The data have a less extreme apo- to pericenter flux ratio than the model, indicating a less eccentric parent body distribution than expected. To constrain the disk geometry and find a model with an appropriate apo- to pericenter flux ratio, we also model the disk using the radiative transfer code MCFOST (Pinte et al. 2006) with a custom eccentric density distribution as input. Our ALMA data also place a low upper limit on the flux density of the circumplanetary disk around HD 106906b, which has the second-largest IR excess of any planetary-mass companion after FW Tau b. Our observations reached a sensitivity that would have detected the FW Tau b circumplanetary disk at a SNR of more than 500, when accounting for the smaller distance to the HD 106906 system. The lack of a circumplanetary disk, as well as the difference between the apo- to peri- flux ratio in the in situ model, suggest that the companion may have formed close to the star and undergone a scattering event to reach its current location.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23530819M