Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): PDS 111, an old T Tauri star with a young-looking disk

¹ Anton Pannekoek Institute for Astronomy (API), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
e-mail: a.r.derkink@uva.nl
² School of Natural Sciences, University of Galway, University Road, H91 TK33 Galway, Ireland
³ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
⁴ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
⁵ Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D bus 2401, 3001 Leuven, Belgium
⁶ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
⁷ Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA
⁸ Université Côte d’Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, 06304 Nice cedex 4, France
⁹ Université Grenoble Alpes, CNRS, Institut de Planétologie et d’Astrophysique (IPAG), 38000 Grenoble, France
¹⁰ University Observatory, Faculty of Physics, Ludwig-Maximilians Universität, Scheinerstr. 1, 81679 Munich, Germany
¹¹ Department of Physics and Astronomy “Galileo Galilei” (DFA), University of Padua, via Marzolo 8, 35131 Padua, Italy
¹² INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
¹³ Leiden Observatory, Leiden University, 2300 RA Leiden, The Netherlands
¹⁴ European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago, Chile
¹⁵ Department of Astronomy, University of Michigan, 323 West Hall, 1085 S. University Avenue, Ann Arbor, MI 48109, USA
¹⁶ Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany
¹⁷ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹⁸ Institute for Astronomy, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
¹⁹ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
²⁰ Millennium Nucleus on Young Exoplanets and their Moons (YEMS), Chile

Received: 10 November 2023
Accepted: 11 May 2024

Abstract

Context. The interplay between T Tauri stars and their circumstellar disks, and how this impacts the onset of planet formation has yet to be established. In the last years, major progress has been made using instrumentation that probes the dust structure in the mid-plane and at the surface of protoplanetary disks. Observations show a great variety of disk shapes and substructures that are crucial for understanding planet formation.

Aims. We studied a seemingly old T Tauri star, PDS 111, and its disk. We combined complementary observations of the stellar atmosphere, the circumstellar hot gas, the surface of the disk, and the mid-plane structure.

Methods. We analyzed optical, infrared, and sub-millimeter observations obtained with VLT/X-shooter, Mercator/HERMES, TESS, VLT/SPHERE, and ALMA, providing a new view on PDS 111 and its protoplanetary disk. The multi-epoch spectroscopy yields photospheric lines to classify the star and to update its stellar parameters, and emission lines to study variability in the hot inner disk and to determine the mass-accretion rate. The SPHERE and ALMA observations are used to characterize the dust distribution of the small and large grains, respectively.

Results. PDS 111 is a weak-line TTauri star with spectral type G2, exhibits strong Hα variability and with a low mass-accretion rate of 1−5 × 10⁻¹⁰ M_⊙ yr⁻¹. We measured an age of the system of 15.9_−3.7^+1.7 Myr using pre-main sequence tracks. The SPHERE observations show a strongly flaring disk with an asymmetric substructure. The ALMA observations reveal a 30 au cavity in the dust continuum emission with a low contrast asymmetry in the South-West of the disk and a dust disk mass of 45.8 M_⊙ or ~0.14 M_Jup. The ¹²CO observations do not show a cavity and the ¹²CO radial extension is at least three times larger than that of the dust emission.

Conclusions. Although the measured age is younger than often suggested in literature, PDS 111 seems relatively old; this provides insight into disk properties at an advanced stage of pre-main sequence evolution. The characteristics of this disk are very similar to its younger counterparts: strongly flaring, an average disk mass, a typical radial extent of the disk gas and dust, and the presence of common substructures. This suggests that disk evolution has not significantly changed the disk properties. These results show similarities with the “Peter Pan disks” around M-dwarfs, that “refuse to evolve”.