Evidence for transit-timing variations of the 11 Myr exoplanet TOI-1227 b

¹ Observatoire de Genève, Département d’Astronomie, Université de Genève, Chemin Pegasi 51b, 1290 Versoix, Switzerland
² Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
e-mail: jose-manuel.almenara-villa@univ-grenoble-alpes.fr
³ Université Côte d’Azur, Laboratoire Lagrange, OCA, CNRS UMR 7293, Nice, France
⁴ Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium
⁵ International Center for Advanced Studies (ICAS) and ICIFI (CONICET), ECyT-UNSAM, Campus Miguelete, 25 de Mayo y Francia, (1650) Buenos Aires, Argentina
⁶ School of Physics & Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
⁷ AIM, CEA, CNRS, Université Paris-Saclay, Université de Paris, 91191 Gif-sur-Yvette, France
⁸ Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
⁹ Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium
¹⁰ Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
¹¹ School of Physics & Astronomy, Monash University, Victoria 3800, Australia
¹² Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
¹³ Dept. Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
¹⁴ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
¹⁵ Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
¹⁶ Department of Aeronautics and Astronautics, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
¹⁷ Department of Astrophysical Sciences, Princeton University, NJ 08544, USA

Received: 4 November 2023
Accepted: 22 December 2023

Abstract

TOI-1227 b is an 11 Myr old validated transiting planet in the middle of its contraction phase, with a current radius of 0.85 R_j. It orbits a low-mass pre-main sequence star (0.170 M_⊙, 0.56 R_⊙) every 27.4 days. The magnetic activity of its young host star induces radial velocity jitter and prevents good measurements of the planetary mass. We gathered additional transit observations of TOI-1227 b with space- and ground-based telescopes, and we detected highly significant transit-timing variations (TTVs). Their amplitude is about 40 min and their dominant timescale is longer than 3.7 yr. Their most probable origin is dynamical interactions with additional planets in the system. We modeled the TTVs with inner and outer perturbers near first and second order resonances; several orbital configurations provide an acceptable fit. More data are needed to determine the actual orbital configuration and eventually measure the planetary masses. These TTVs and an updated transit chromaticity analysis reinforce the evidence that TOI-1227 b is a planet.