Debris Disks

My group is also leading studies of debris disks and disk-planet interactions. These studies allow us to explore the evolution of planetary systems and constrain planetary architectures at orbital radii beyond those accessible to transiting planet and radial velocity surveys.

Two examples for our debris disk work:

The Inner Disk Structure, Disk-Planet Interactions, and Temporal Evolution in the Beta Pictoris System: Two-Epoch HST/STIS Coronagraphic Study

Beta Pictoris is arguably the largest and most spectacular debris disk seen from Earth. This 20 Myr-old dust disk was the first to be directly imaged and has been studied in great details over the past thirty years, leading to over 800 refereed papers.

Beta Pictoris Debris Disk

Our HST/STIS coronagraphic image of the majestic Beta Pictoris debris disk (from Apai et al. 2015 ApJ)

In our 2015 study we used the Hubble Space Telescope’s STIS instrument and its coronagraph to obtain the highest-quality optical image of the disk yet. Excitingly, we were also able to image the disk very close to the host star, at the same projected radius where the giant exoplanet Beta Pictoris b orbits.

Our study combined the STIS optical image with images taken at different wavelengths, ranging from near-infrared through mid-infrared to sub-millimeter. The different wavelength allowed us to compare the location and morphology of different disk components (small,  medium, and large dust grains, grains with different composition, CO gas) and constrain the recent history of the disk. One particularly interesting aspect of the study is identifying disk structures introduced by the gravitational influence of the giant planet, which orbits on an inclined orbit.

Our exciting results were also highlighted in an HST press release:
Hubble Gets Best View of a Circumstellar Debris Disk Distorted by a Planet

Check out our Google Hangout discussion of the results.

A survey for massive giant planets in debris disks with evacuated inner cavities

In this study we used the VLT/NACO adaptive optics system to obtain high-contrast images of debris disks that have massive outer disks but depleted or no inner disks. Our goal was to test the hypothesis that the inner disks in these systems are cleared out by single massive giant planets. Our NACO observations reached 3-6 jupiter mass sensitivities at the inner disk radii in most systems, but no system contained a super-jupiter at these locations. Thus, the results of our survey argued against single massive planets clearing out the inner disks; multiple, low-mass planets in resonant orbits remain the most likely possibility.