Hα and He I absorption in HAT-P-32 b observed with CARMENES

Detection of Roche lobe overflow and mass loss

¹ Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: stefan.czesla@hs.uni-hamburg.de
² Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
³ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁴ Centro de Astrobiología (CSIC-INTA), ESAC, Camino bajo del castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
⁵ AIM, CEA, CNRS, Université Paris-Saclay, Université de Paris, 91191 Gif-sur-Yvette, France
⁶ Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
⁷ Yunnan Observatories, Chinese Academy of Sciences, PO Box 110, Kunming 650011, PR China
⁸ School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing, PR China
⁹ Centro Astronómico Hispano Alemán, Sierra de los Filabres, 04550 Gérgal, Almería, Spain
¹⁰ Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
¹¹ Departamento de Astrofísica, Universidad de La Laguna, 38206 Tenerife, Spain
¹² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹³ Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany
¹⁴ Universitäts-Sternwarte, Ludwig-Maximilians-Universität München, Scheinerstrasse 1, 81679 München, Germany
¹⁵ Facultad de Ciencias Físicas, Departamento de Física de la Tierra y Astrofísica; IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁶ Institut de Ciències de l’Espai (ICE, CSIC), Campus UAB, c/ de Can Magrans s/n, 08193 Bellaterra, Barcelona, Spain
¹⁷ Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
¹⁸ Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain

Received: 14 November 2020
Accepted: 30 August 2021

Abstract

We analyze two high-resolution spectral transit time series of the hot Jupiter HAT-P-32 b obtained with the CARMENES spectrograph. Our new XMM-Newton X-ray observations of the system show that the fast-rotating F-type host star exhibits a high X-ray luminosity of 2.3 × 10²⁹ erg s⁻¹ (5–100 Å), corresponding to a flux of 6.9 × 10⁴ erg cm⁻² s⁻¹ at the planetary orbit, which results in an energy-limited escape estimate of about 10¹³ g s⁻¹ for the planetary mass-loss rate. The spectral time series show significant, time-dependent absorption in the Hα and He Iλ10833 triplet lines with maximum depths of about 3.3% and 5.3%. The mid-transit absorption signals in the Hα and He Iλ10833 lines are consistent with results from one-dimensional hydrodynamic modeling, which also yields mass-loss rates on the order of 10¹³ g s⁻¹. We observe an early ingress of a redshifted component of the transmission signal, which extends into a redshifted absorption component, persisting until about the middle of the optical transit. While a super-rotating wind can explain redshifted ingress absorption, we find that an up-orbit stream, transporting planetary mass in the direction of the star, also provides a plausible explanation for the pre-transit signal. This makes HAT-P-32 a benchmark system for exploring atmospheric dynamics via transmission spectroscopy.