Developing the Flexible Image Gallery Generator (FIGG) to Explore Transitional Disk Substructures

We developed the Flexible Image Gallery Generator (FIGG) Python package to provide a powerful processing tool for constructing image grids through a straightforward user interface. FIGG allows for a user to crop, normalize, mask, label, and display a set of .fits format science images using a simple Google Sheets interface. Images can be arranged flexibly, for example by morphological classification or spectral types. FIGG uses a combination of pixel normalization, custom colormap scaling, background reduction, and convolution smoothing to standardize visual processing and improve the immediate visibility of a range of physical structures. We utilized FIGG to examine a set of newly-compiled near-infrared images of transitional disks from an international collaboration between the VLT-SPHERE, GPI, and Subaru teams. Transitional circumstellar disks are characterized by their large, central cavities, which are predicted to be sites of ongoing planet formation. In addition to their characteristic central gaps, they host a range of morphological features. Known as substructures, many of these features are believed to be induced by the presence of planets within the disk. Although hundreds of studies of individual transitional disk systems have been conducted in the past decade, there is still much to learn about transitional disks as a population. Applying FIGG to this image set, we were able to visualize and compare substructures within the population despite the large variation in spatial and flux scales across spectral types, distances, and instruments. Using the galleries we generated, we were able to classify the disks in our sample by eye into common substructure types, including: rings, spirals, shadows, back sides, etc. Furthermore, we were able to demonstrate the existence of all of these substructures across spectral types ranging from M to A/B. This anecdotal evidence calls into question the conventional wisdom that some disk substructures (e.g., spiral arms) exist only in the disks of stars of certain spectral types.