CO Line Emission Surfaces and Vertical Structure in Mid-Inclination Protoplanetary Disks
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/r\approx0.1$ to ${\gtrsim}0.5$) 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 ${\approx}2$-$5\times$ gas pressure scale heights (H$_{\rm{g}}$) and could potentially be calibrated as empirical tracers of H$_{\rm{g}}$.
Authors 21
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Affiliation as printed
Department of Astronomy, University of Michigan, 323 West Hall, 1085 South University Ave., Ann Arbor, MI 48109, USA
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Affiliation as printed
Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
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Affiliation as printed
Department of Astronomy and Department of Physics, Williams College, Williamstown, MA 01267, USA
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Pontificia Universidad Católica de Chile
Affiliation as printed
Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
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Affiliation as printed
Department of Astronomy, University of Michigan, 323 West Hall, 1085 South University Ave., Ann Arbor, MI 48109, USA
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Affiliation as printed
School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
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Rochester Institute of Technology
Affiliation as printed
Chester F. Carlson Center for Imaging Science, School of Physics & Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, Rochester, NY 14623, USA
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National Radio Astronomy Observatory
Affiliation as printed
National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Millenium Nucleus for Planet Formation · University of Chile
Affiliation as printed
Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
Núcleo Milenio de Formación Planetaria (NPF), Chile
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Universidad de Santiago de Chile
Affiliation as printed
Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS), Universidad de Santiago de Chile, Chile
Departamento de Física, Universidad de Santiago de Chile. Avenida Ecuador 3493, Estación Central, Santiago, Chile
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands
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National Radio Astronomy Observatory
Affiliation as printed
National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA
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National Astronomical Observatory of Japan
Affiliation as printed
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
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