The morphology of CS Cha circumbinary disk suggesting the existence of a Saturn-mass planet

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
e-mail: kurtovic@mpia.de
² Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
³ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
⁴ Institut für Astronomie und Astrophysik, Universität Tübingen, Auf der Morgenstelle 10, 72076, Germany
⁵ Unidad Mixta Internacional Franco-Chilena de Astronomía (CNRS UMI 3386), Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 33, Las Condes, Santiago, Chile
⁶ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁷ Núcleo Milenio de Formación Planetaria (NPF), Chile
⁸ Millennium Nucleus on Young Exoplanets and their Moons (YEMS), Universidad de Santiago de Chile, Av. Libertador Bernardo O’Higgins 3363, Santiago, Chile
⁹ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
¹⁰ Department of Physics and Astronomy, Rice University, 6100 Main Street, MS-108, Houston, TX 77005, USA
¹¹ Departamento de Física, Universidad de Santiago de Chile, Av. Victor Jara 3659, Santiago
¹² Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS), Universidad de Santiago de Chile, Estación Central, Chile
¹³ Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaiso, Av. Gran Bretaña 1111, Playa Ancha, Valparaiso, Chile

Received: 9 March 2022
Accepted: 27 May 2022

Abstract

Context. Planets have been detected in circumbinary orbits in several different systems, despite the additional challenges faced during their formation in such an environment.

Aims. We investigate the possibility of planetary formation in the spectroscopic binary CS Cha by analyzing its circumbinary disk.

Methods. The system was studied with high angular resolution ALMA observations at 0.87 mm. Visibilities modeling and Keplerian fitting are used to constrain the physical properties of CS Cha, and the observations were compared to hydrodynamic simulations.

Results. Our observations are able to resolve the disk cavity in the dust continuum emission and the ¹²CO J:3–2 transition. We find the dust continuum disk to be azimuthally axisymmetric (less than 9% of intensity variation along the ring) and of low eccentricity (of 0.039 at the peak brightness of the ring).

Conclusions. Under certain conditions, low eccentricities can be achieved in simulated disks without the need of a planet, however, the combination of low eccentricity and axisymmetry is consistent with the presence of a Saturn-like planet orbiting near the edge of the cavity.