English

CO Line Emission Surfaces and Vertical Structure in Mid-Inclination Protoplanetary Disks

Earth and Planetary Astrophysics 2022-06-29 v1 Astrophysics of Galaxies Solar and Stellar Astrophysics

Abstract

High spatial resolution CO observations of mid-inclination (30-75{\deg}) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically-thick, spatially-resolved emission in LTE, the intensity is a measure of the local gas temperature. Our analysis of ALMA archival data yields CO emission surfaces, dynamically-constrained stellar host masses, and disk atmosphere gas temperatures for the disks around: HD 142666, MY Lup, V4046 Sgr, HD 100546, GW Lup, WaOph 6, DoAr 25, Sz 91, CI Tau, and DM Tau. These sources span a wide range in stellar masses (0.50-2.10 M_{\odot}), ages ({\sim}0.3-23 Myr), and CO gas radial emission extents ({\approx}200-1000 au). This sample nearly triples the number of disks with mapped emission surfaces and confirms the wide diversity in line emitting heights (z/r0.1z/r\approx0.1 to 0.5{\gtrsim}0.5) hinted at in previous studies. We compute radial and vertical CO gas temperature distributions for each disk. A few disks show local temperature dips or enhancements, some of which correspond to dust substructures or the proposed locations of embedded planets. Several emission surfaces also show vertical substructures, which all align with rings and gaps in the millimeter dust. Combining our sample with literature sources, we find that CO line emitting heights weakly decline with stellar mass and gas temperature, which, despite large scatter, is consistent with simple scaling relations. We also observe a correlation between CO emission height and disk size, which is due to the flared structure of disks. Overall, CO emission surfaces trace 2{\approx}2-5×5\times gas pressure scale heights (Hg_{\rm{g}}) and could potentially be calibrated as empirical tracers of Hg_{\rm{g}}.

Keywords

Cite

@article{arxiv.2205.01776,
  title  = {CO Line Emission Surfaces and Vertical Structure in Mid-Inclination Protoplanetary Disks},
  author = {Charles J. Law and Sage Crystian and Richard Teague and Karin I. Öberg and Evan A. Rich and Sean M. Andrews and Jaehan Bae and Kevin Flaherty and Viviana V. Guzmán and Jane Huang and John D. Ilee and Joel H. Kastner and Ryan A. Loomis and Feng Long and Laura M. Pérez and Sebastián Pérez and Chunhua Qi and Giovanni P. Rosotti and Dary Ruíz-Rodríguez and Takashi Tsukagoshi and David J. Wilner},
  journal= {arXiv preprint arXiv:2205.01776},
  year   = {2022}
}

Comments

31 pages, 17 figures, accepted for publication in ApJ. Image cubes available at https://zenodo.org/record/6410045