The MOPYS project: A survey of 70 planets in search of extended He I and H atmospheres

No evidence of enhanced evaporation in young planets

¹ Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
³ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁴ Centro de Astrobiología (CSIC-INTA), Camino Bajo del Castillo s/n, Villanueva de la Cañada, 28692 Madrid, Spain
⁵ Institut für Astrophysik und Geophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
⁶ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
⁷ Institut de Ciències de l’Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Barcelona, Spain
⁸ Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
⁹ Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
¹⁰ Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹¹ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
¹² Astronomical Science Program, Graduate University for Advanced Studies, SOKENDAI, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
¹³ Department of Space, Earth and Environment, Chalmers University of Technology, 412 93, Gothenburg, Sweden
¹⁴ Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
¹⁵ Division of Geological and Planetary Sciences, 1200 E California Blvd, Pasadena, CA 91125, USA
¹⁶ Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
¹⁷ Komaba Institute for Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
¹⁸ Faculty of Physics, Ludwig Maximilian University, Scheinerstrasse 1, 81679 Munich, Bavaria, Germany
¹⁹ Max-Planck-Institute für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
²⁰ Department of Multi-Disciplinary Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo
²¹ Departamento de Física de la Tierra y Astrofísica and IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
²² Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
²³ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
²⁴ Centro Astronómico Hispano en Andalucía, Observatorio Astronómico de Calar Alto, Sierra de los Filabres, 04550 Gérgal, Almería, Spain

Received: 30 January 2024
Accepted: 30 May 2024

Abstract

During the first billion years of their life, exoplanet atmospheres are modified by different atmospheric escape phenomena that can strongly affect the shape and morphology of the exoplanet itself. These processes can be studied with Lyα, Hα, and/or He I triplet observations. We present high-resolution spectroscopy observations from CARMENES and GIARPS checking for He I and Hα signals in 20 exoplanetary atmospheres: V1298 Tau c, K2-100 b, HD 63433 b, HD 63433 c, HD 73583 b, HD 73583 c, K2-77 b, TOI-2076 b, TOI-2048 b, HD 235088 b, TOI-1807 b, TOI-1136 d, TOI-1268 b, TOI-1683 b, TOI-2018 b, MASCARA-2b, WASP-189 b, TOI-2046 b, TOI-1431 b, and HAT-P-57 b. We report two new high-resolution spectroscopy He I detections for TOI-1268 b and TOI-2018 b, and a Hα detection for TOI-1136 d. Furthermore, we detect hints of He I for HD 63433 b, and Hα for HD 73583 b and c, which need to be confirmed. The aim of the Measuring Out-flows in Planets orbiting Young Stars (MOPYS) project is to understand the evaporating phenomena and test their predictions from the current observations. We compiled a list of 70 exoplanets with He I and/or Hα observations, from this work and the literature, and we considered the He I and Hα results as proxy for atmospheric escape. Our principal results are that 0.1–1 Gyr planets do not exhibit more He I or Hα detections than older planets, and evaporation signals are more frequent for planets orbiting ~1–3 Gyr stars. We provide new constraints to the cosmic shoreline, the empirical division between rocky planets and planets with atmosphere, by using the evaporation detections and we explore the capabilities of a new dimensionless parameter, R_He/R_Hill, to explain the He I triplet detections. Furthermore, we present a statistically significant upper boundary for the He I triplet detections in the T_eq versus ρ_p parameter space. Planets located above that boundary are unlikely to show He I absorption signals.