A Study of Protoplanetary Disk Evolution in Infrared CO




Sanchez, Michael A.

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The inner radii (< 10 AU) of protoplanetary disks (PPDs) are the birthplaces of exoplanets. Understanding what happens at these planet-forming distances requires the knowledge of inner gaseous disk evolution. Carbon monoxide (<sup>12</sup>CO; hereafter CO) gas is known to be an effective tracer of excited molecular gas at small radii (0.01 AU – 10 AU). Therefore, in this work, the depletion of molecular gas is traced as the planet-forming regions of PPDs evolve and become gas-poor. To probe CO gas properties, a LTE (local thermal equilibrium) molecular excitation model is employed. Spectral emission of CO and H<sub>2</sub> (molecular hydrogen) gas are compared to analyze gas properties in both gas-rich, full disks and gas-poor transition disks. This approach demonstrates a radial stratification of molecular gas: CO lines are increasingly narrower than H2 lines for disks with large inner gaps, or cavities, suggesting a recession of CO gas in the inner disk. In this thesis, I report results from an excitation analysis of CO spectra to identify how inner disk gas properties change as inner dust cavities form.



Protoplanetary disks, Emission spectroscopy, Astronomy, Astrophysics


Sánchez, M. A. (2021). <i>A study of protoplanetary disk evolution in infrared CO</i> (Unpublished thesis). Texas State University, San Marcos, Texas.


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