Sunburst
A zoomable sunburst chart visualizes the hierarchical flare dataset, showing nested categories as concentric rings where each arc's angular width represents its value. The visualization collapses or expands levels when a user clicks on an arc or the central circle, with smooth transitions animating the radial layout. Built with D3 v5, the code uses `d3.hierarchy`, `d3.partition`, and `d3.arc` to compute the layout, while `transition.attrTween` and `d3.interpolate` animate arc geometry during zoom. The color scale uses `d3.scaleOrdinal` and `d3.interpolateRainbow`, and data loads asynchronously via the Observable `require` API.