Live Poster Session: Zoom Link
Abstract: Circumstellar disks are flat structures of gas and dust around main sequence stars, analogous to the Kuiper belt in our own solar system. Younger disks tend to be gas-rich, while older disks, called debris disks, tend to be gas-poor. However, gas has been detected in an increasing number of debris disks, such as the one around 49 Ceti. The origin of this gas is poorly understood. If it has primordial origins, then the gas must survive the dissipation of initial disk dust. If it has second generation origins, then it is released by collisions between icy planetesimals. Understanding the origin of the gas is important to understanding more about giant planet formation timescales, composition, and mass limits. One way to differentiate between primordial and second generation gas is to determine the scale height, h, which is a measure of the disk’s vertical puffiness. Disks with primordial gas are dominated by light molecules like H2 and will have a greater scale height than disks with second generation gas, since this gas is mostly C and O. We used 12CO(J=3-2) emission data from the Atacama Large Millimeter/submillimeter Array (ALMA) to model the gas in the debris disk around 49 Ceti. We then used a Markov Chain Monte Carlo (MCMC) algorithm to constrain the scale height by finding a best fit model, with a best fit value of h = 9 au at a radius of 150 au. This suggests consistency with second generation origins, which we expect to confirm with a C18O line ratio.
HLewis_RIS2021-poster