A multidimensional study of kinematics and excitation of molecular gas in planet-forming regions

Perez Chavez, Jose A.
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Protoplanetary disks are rotating gas and dust around young, pre main sequence stars and are predecessors to planetary systems like our solar system. The fundamental rovibrational emission band of CO at 4.7 μm is a key diagnostic of the structure of the warm inner 10 AU and planet-forming regions in these disks. By observing CO at high spectral resolution, we distinguish double peak and triangular shaped emission lines that trace Keplerian disk rotation and an additional slow wind component, respectively. To better understand the dichotomy between these lines and the structure of inner disks we employ a multidimensional study on a sample of 51 protoplanetary disks from two high resolution spectroscopy surveys using VLT-CRIRES and IRTF-iSHELL. We studied CO emission excitation and emitting regions with conjunction of star/disk properties including stellar mass, disk inclination, accretion luminosity, and infrared index that traces inner disk cavities. We find three main emitting regions of Keplerian emission based on the host stellar masses: gas within cavities for 1.5-2 M⊙, gas on a surface layer for 1.7-3.6 M⊙, gas at the inner rim of the disk for 3.5-5.2 M⊙. For wind emission we find an interesting case of molecular winds emitting at 0.5-35 AU from the stars, well inside large cavities of up to 70 AU. We discuss the excitation environments, emitting regions, and structures of these cases to improve our understanding of CO molecular gas emission in these planet-forming regions.
Protoplanetary disks, Infrared
Pérez Chávez, J. A. (2022). <i>A multidimensional study of kinematics and excitation of molecular gas in planet-forming regions</i> (Unpublished thesis). Texas State University, San Marcos, Texas.