First Detection of HC5N Within A Protoplanetary Disk

Since ALMA's first light in 2011, the molecular inventory of protoplanetary disks has dramatically increased, to including the detection of complex organic molecules (COMs) such as CH3CN, HCOOH, and HC3N. These COMs not only present an opportunity to investigate the prebiotic chemistry of forming planetary systems, but they also act as valuable physical tracers of fundamental disk properties. Continuing to expand this molecular inventory to more complex species both allows for refinement of chemical models and adds new tracers of disk physics to our toolbox.

Here we present the first detection of HC5N toward the nearest protoplanetary disk TW Hya; the largest species detected thus far in disks. With such a high molecular mass, HC5N has very little thermal broadening. This combined with its low optical depth provides a chance to probe turbulence within the planet and comet forming midplanes of protoplanetary disks. We discuss these possibilities within the context of the increased sensitivity and spectral resolution of ALMA's upcoming Wideband Sensitivity Upgrade and the ngVLA.