A highly non-Keplerian protoplanetary disc

Astronomy and Astrophysics, vol. 648, pp. A19

Abstract

Context. In recent years high-angular-resolution observations have revealed that circumstellar discs appear in a variety of shapes with diverse substructures being ubiquitous. This has given rise to the question of whether these substructures are triggered by planet–disc interactions. Besides direct imaging, one of the most promising methods to distinguish between different disc-shaping mechanisms is to study the kinematics of the gas disc. In particular, the deviations of the rotation profile from Keplerian velocity can be used to probe perturbations in the gas pressure profile that may be caused by embedded (proto-) planets. Aims. In this paper we aim to analyse the gas brightness temperature and kinematics of the transitional disc around the intermediate-mass star CQ Tau in order to resolve and characterise substructure in the gas caused by possible perturbers. Methods. For our analysis we used spatially resolved ALMA observations of the three CO isotopologues 12 CO, 13 CO, and C 18 O ( J = 2−1) from the disc around CQ Tau. We further extracted robust line centroids for each channel map and fitted a number of Keplerian disc models to the velocity field. Results. The gas kinematics of the CQ Tau disc present non-Keplerian features, showing bent and twisted iso-velocity curves in 12 CO and 13 CO. Significant spiral structures are detected between ~10 and 180 au in both the brightness temperature and the rotation velocity of 12 CO after subtraction of an azimuthally symmetric model, which may be tracing planet–disc interactions with an embedded planet or low-mass companion. We identify three spirals, two in the brightness temperature and one in the velocity residuals, spanning a large azimuth and radial extent. The brightness temperature spirals are morphologically connected to spirals observed in near-infrared scattered light in the same disc, indicating a common origin. Together with the observed large dust and gas cavity, these spiral structures support the hypothesis of a massive embedded companion in the CQ Tau disc.

Authors 12

1. Lisa Wölfer

   Max Planck Institute for Extraterrestrial Physics · Ludwig-Maximilians-Universität München

   Affiliation as printed

   Max-Planck-Institut für extraterrestrische Physik, Gießenbachstr. 1, 85748 Garching bei München, Germany

   Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München, Germany

2. Stefano Facchini

   European Southern Observatory

   Affiliation as printed

   European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany

3. N. T. Kurtovic

   Max Planck Institute for Astronomy · University of Chile

   Affiliation as printed

   Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile

   Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

4. Richard D. Teague

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA

5. Ewine F. van Dishoeck Aachen Leiden Observatory

   Leiden University · Max Planck Institute for Extraterrestrial Physics · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

   Max-Planck-Institut für extraterrestrische Physik, Gießenbachstr. 1, 85748 Garching bei München, Germany

6. M. Benisty

   Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · University of Chile · Université Grenoble Alpes

   Affiliation as printed

   Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile

   Unidad Mixta Internacional Franco-Chilena de Astronomía, CNRS, UMI 3386, Chile

   Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

7. Barbara Ercolano

   Excellence Cluster Universe · Ludwig-Maximilians-Universität München

   Affiliation as printed

   Excellence Cluster Origin and Structure of the Universe, Boltzmannstr. 2, 85748 Garching bei München, Germany

   Universitäts-Sternwarte München, Scheinerstr. 1, 81679 München, Germany

8. Giuseppe Lodato

   University of Milan

   Affiliation as printed

   Dipartimento di Fisica, Università degli Studi di Milano, Via Giovanni Celoria 16, 20133 Milano, Italy

9. Anna Miotello

   European Southern Observatory

   Affiliation as printed

   European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany

10. Giovanni P. Rosotti Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

11. L. Testi

    European Southern Observatory · Arcetri Astrophysical Observatory · Excellence Cluster Universe

    Affiliation as printed

    European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany

    Excellence Cluster Origin and Structure of the Universe, Boltzmannstr. 2, 85748 Garching bei München, Germany

    INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

12. Maria Giulia Ubeira-Gabellini

    European Southern Observatory · University of Milan

    Affiliation as printed

    Dipartimento di Fisica, Università degli Studi di Milano, Via Giovanni Celoria 16, 20133 Milano, Italy

    European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany