Distributions of gas and small and large grains in the LkHα 330 disk trace a young planetary system^★,★★

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: pinilla@mpia.de
² Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
³ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁴ Unidad Mixta Internacional Franco-Chilena de Astronomía, CNRS, UMI 3386. Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
⁵ Department of Astronomy, University of Florida, 316 Bryant Space Science Building, Gainesville, FL 32611, USA
⁶ Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1, Canada
⁷ Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154, USA
⁸ Nevada Center for Astrophysics, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154, USA
⁹ Center for Astrophysics – Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
¹⁰ Joint ALMA Observatory, Avenida Alonso de Córdova 3107 Vitacura, Santiago, Chile
¹¹ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
¹² Leiden Observatory, Leiden University, 2300 RA Leiden, The Netherlands
¹³ NASA Hubble Fellowship Program Sagan Fellow, Department of Astronomy, University of Michigan, 323 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USA
¹⁴ Department of Physics and Astronomy, Rice University, 6100 Main Street, MS-61, Houston, TX 77005, USA
¹⁵ Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
¹⁶ Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA
¹⁷ School of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
¹⁸ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA

Received: 4 April 2022
Accepted: 19 June 2022

Abstract

Planets that are forming around young stars are expected to leave clear imprints in the distribution of the gas and dust of their parental protoplanetary disks. In this paper, we present new scattered light and millimeter observations of the protoplanetary disk around LkHα 330, using SPHERE/VLT and ALMA, respectively. The scattered-light SPHERE observations reveal an asymmetric ring at around 45 au from the star in addition to two spiral arms with similar radial launching points at around 90 au. The millimeter observations from ALMA (resolution of 0.06″ × 0.04″) mainly show an asymmetric ring located at 110 au from the star. In addition to this asymmetry, there are two faint symmetric rings at 60 au and 200 au. The ¹²CO, ¹³CO, and C¹⁸O lines seem to be less abundant in the inner disk (these observations have a resolution of 0.16″ × 0.11″). The ¹³CO peaks at a location similar to the inner ring observed with SPHERE, suggesting that this line is optically thick and traces variations of disk temperature instead of gas surface-density variations, while the C¹⁸O peaks slightly further away at around 60 au. We compare our observations with hydrodynamical simulations that include gas and dust evolution, and conclude that a 10 M_Jup mass planet at 60 au and in an eccentric orbit (e = 0.1) can qualitatively explain most of the observed structures. A planet in a circular orbit leads to a much narrower concentration in the millimeter emission, while a planet in a more eccentric orbit leads to a very eccentric cavity as well. In addition, the outer spiral arm launched by the planet changes its pitch angle along the spiral due to the eccentricity and when it interacts with the vortex, potentially appearing in observations as two distinct spirals. Our observations and models show that LkHα 330 is an interesting target to search for (eccentric-) planets while they are still embedded in their parental disk, making it an excellent candidate for studies on planet-disk interaction.