CO Line Emission Surfaces and Vertical Structure in Midinclination Protoplanetary Disks

The Astrophysical Journal, vol. 932, pp. 114

Abstract

Abstract High spatial resolution CO observations of midinclination (≈30°–75°) 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 Atacama Large Millimeter/submillimeter Array archival data yields CO emission surfaces, dynamically constrained stellar host masses, and disk atmosphere gas temperatures for the disks around the following: 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 ⊙), ages (∼0.3–23 Myr), and CO gas radial emission extents (≈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 ≈ 0.1 to ≳0.5) hinted at in previous studies. We compute the 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 ≈2–5× gas pressure scale heights (Hg) and could potentially be calibrated as empirical tracers of Hg.

Authors 16

1. Charles J. Law

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA

2. Sage Crystian

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA

3. Richard D. Teague

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA

4. Karin I. Öberg

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA

5. Evan A. Rich

   University of Michigan

   Affiliation as printed

   Department of Astronomy, University of Michigan, 323 West Hall, 1085 South University Ave., Ann Arbor, MI 48109, USA

6. Sean M. Andrews

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA

7. Jaehan Bae

   University of Florida

   Affiliation as printed

   Department of Astronomy, University of Florida, Gainesville, FL 32611, USA

8. Viviana Veloso Guzmán

   Pontificia Universidad Católica de Chile

   Affiliation as printed

   Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile

9. Jane Huang

   University of Michigan

   Affiliation as printed

   Department of Astronomy, University of Michigan, 323 West Hall, 1085 South University Ave., Ann Arbor, MI 48109, USA

10. John D. Ilee

    University of Leeds

    Affiliation as printed

    School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK

11. Joel H. Kastner

    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

12. Ryan A. Loomis

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA

13. Giovanni P. Rosotti Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands

14. Dary A. Ruiz-Rodriguez

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA

15. Takashi Tsukagoshi

    National Astronomical Observatory of Japan

    Affiliation as printed

    National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

16. David J. Wilner

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

    Center for Astrophysics ∣ Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA