Hα and He I absorption in HAT-P-32 b observed with CARMENES Detection of Roche lobe overflow and mass loss

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 x 10(29) erg s(-1) (5-100 A), corresponding to a flux of 6.9 x 10(4) erg cm(-2) s(-1) at the planetary orbit, which results in an energy-limited escape estimate of about 10(13) g s(-1) for the planetary mass-loss rate. The spectral time series show significant, time-dependent absorption in the H alpha and He I lambda 10833 triplet lines with maximum depths of about 3.3% and 5.3%. The mid-transit absorption signals in the H alpha and He I lambda 10833 lines are consistent with results from one-dimensional hydrodynamic modeling, which also yields mass-loss rates on the order of 10(13) 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.