We report the detection and characterization of the transiting sub-Neptune TOI-1759 b, using photometric time series from the Transiting Exoplanet Survey Satellite (TESS) and near-infrared spectropolarimetric data from the Spectro-Polarimètre Infra Rouge (SPIRou) on the Canada-France-Hawaii Telescope. TOI-1759 b orbits a moderately active M0V star with an orbital period of 18.849975 ± 0.000006 days, and we measured a planetary radius and mass of 3.06 ± 0.22 R⊕ and 6.8 ± 2.0 M⊕. Radial velocities were extracted from the SPIRou spectra using both the cross-correlation function and the line-by-line methods, optimizing the velocity measurements in the near-infrared domain. We analyzed the broadband spectral energy distribution of the star and the high-resolution SPIRou spectra to constrain the stellar parameters and thus improve the accuracy of the derived planet parameters. A least squares deconvolution analysis of the SPIRou Stokes V polarized spectra detects Zeeman signatures in TOI-1759. We modeled the rotational modulation of the magnetic stellar activity using a Gaussian process regression with a quasi-periodic covariance function and find a rotation period of 35.65−0.15+0.17 days. We reconstructed the large-scale surface magnetic field of the star using Zeeman-Doppler imaging, which gives a predominantly poloidal field with a mean strength of 18 ± 4 G. Finally, we performed a joint Bayesian Markov chain Monte Carlo analysis of the TESS photometry and SPIRou radial velocities to optimally constrain the system parameters. At 0.1176 ± 0.0013 au from the star, the planet receives 6.4 times the bolometric flux incident on Earth, and its equilibrium temperature is estimated at 433 ± 14 K. TOI-1759 b is a likely gas-dominated sub-Neptune with an expected high rate of photoevaporation. Therefore, it is an interesting target to search for neutral hydrogen escape, which may provide important constraints on the planetary formation mechanisms responsible for the observed sub-Neptune radius desert.

We simulate possible stellar coronal mass ejection (CME) scenarios over the magnetic cycle of ϵ Eridani (18 Eridani; HD 22049). We use three separate epochs from 2008, 2011, and 2013, and estimate the radio emission frequencies associated with these events. These stellar eruptions have proven to be elusive, although a promising approach to detect and characterize these phenomena are low-frequency radio observations of potential type II bursts as CME-induced shocks propagate through the stellar corona. Stellar type II radio bursts are expected to emit below 450 MHz, similarly to their solar counterparts. We show that the length of time these events remain above the ionospheric cutoff is not necessarily dependent on the stellar magnetic cycle, but more on the eruption location relative to the stellar magnetic field. We find that these type II bursts would remain within the frequency range of LOFAR for a maximum of 20-30 minutes post-eruption for the polar CMEs (50 minutes for second harmonics). We find evidence of slower equatorial CMEs, which result in slightly longer observable windows for the 2008 and 2013 simulations. Stellar magnetic geometry and strength have a significant effect on the detectability of these events. We place the CMEs in the context of the stellar mass-loss rate (27-48× solar mass-loss rate), showing that they can amount to 3%-50% of the stellar wind mass-loss rate for ϵ Eridani. Continuous monitoring of likely stellar CME candidates with low-frequency radio telescopes will be required to detect these transient events.

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The accurate description of quantum effects, particularly quantum tunneling[1], in bimolecular chemical reactions constitutes one of the major goals of theoretical chemistry. Due to an unfavorable scaling law, exact quantum scattering methods lead to expensive and often unfeasible simulations when considering chemical systems with a large number of degrees of freedom. Moreover, at low temperature quantum effects often do not represent a small correction to classical calculations, but contrariwise are essential to obtain quantitative results. In this talk, I will show the feasibility of accurate quantum stationary scattering simulations for high dimensional systems using hybrid quantum-classical trajectories[2]. The configuration space is partitioned in one reaction coordinate going from reactants to products along which trajectories reproduce quantum effects, and bath coordinates with small amplitude motion which are treated classically[3]. Quantization of bath modes by a semi-classical phase-space sampling approximation based on Wigner-Weyl mapping allows to accurately reproduce quantum structure effects such as reaction thresholds. As was acknowledged many years ago [4], when the motion along the reaction coordinate is sufficiently slow compared to perpendicular motion, both subsystems undergo adiabatic evolution. By taking advantage from the local character of trajectory dynamics, I will illustrate how on-the-fly conversion from position-momenta to action-angle representation for bath coordinates in specific regions of vibrational adiabaticity leads to a computationally efficient scheme[5].