The vast majority of the detected exoplanets orbit in less than a month around their star, in extreme conditions unmet in the Solar System. The demographics of these close-in planets exhibit a striking feature: the lack of Neptune-size worlds on very short orbits, also dubbed the ‘Neptunian desert’, which challenges our understanding of planetary formation and evolution. 

Two classes of mechanisms thought to play a predominant role in shaping the desert are orbital migration, which brings such planets close to their star, and atmospheric escape under the resulting increased irradiation. Yet, their relative roles remain poorly assessed, in part because we lack numerical models that couple the two processes with high precision and on secular timescales.

To address this need, we developed a state-of-the-art model, the JADE code, which allows to self-consistently simulate the complete lifetime of close-in planets. We bench-marked the JADE code on the intriguing case of GJ436b, and showed that its exciting properties can be naturally explained by a strong interplay between eventful orbital and atmospheric histories.

Precise measurements of orbital and atmospheric tracers are crucial to constrain our models. Our joined approach to the understanding of past dynamical and atmospheric history, combined with the servicing of next-generation instruments, offers the best chance to shed light on the origins of the desert and the processes that forge the close-in planet population.

Article:
‘The JADE code: Coupling secular exoplanetary dynamics and photo-evaporation’, Attia, O.; Bourrier, V.; Eggenberger, P.; Mordasini, C.; Beust, H.; Ehrenreich, D., Astronomy & Astrophysics, Volume 647, id.A40, 19 pp.

The search of extrasolar planets around nearby M-dwarfs is a crucial step in the long term goal of identifying and characterising extrasolar planets that could potentially host life in the vicinity of the solar system. We have obtained radial velocity time series of the nearby active M-dwarf star Gl 388 (AD Leo) from 2019 to 2020 with SPIRou, the near-IR spectropolarimeter at the Canada France Hawaii Telescope (R~70k), and with SOPHIE, the optical echelle spectrograph (R~75k) at the Observatoire de Haute Provence in France. We aim to settle the controversy whether the 2.2 day period radial velocity signal observed by previous observations in the optical is due to stellar activity (Morin et al. 2008, Bonfils et al. 2013) or due to a 0.2 MJ planet in spin-orbit resonance (Toumi et al. 2018). We achieved a radial velocity precision of a few m/s within the SPIRou and SOPHIE observations. The SOPHIE RV measurements display the previously reported periodic variation at 2.2 days period and ~20 m/s amplitude. The SPIRou RV series do not display periodic variations at a 2.2 days period and a periodogram analysis exclude them with a high confidence level. As the RV variation reported in the optical data would have been easily detected within the near-IR RV time series, our SPIRou data provide strong evidence that the periodic RV variability observed in the optical spectra of Gl 388 is due to stellar magnetic activity, thus that there is no  2.2 day period planet orbiting the star. High-precision radial velocity (RV) in the near-IR is a powerful tool to search for planets around active stars and to confirm/disconfirm planets candidates revealed by optical radial velocities.

One of the exoplanet research programmes carried out with SOPHIE focuses on the detection and characterisation of super-Earth and Neptune-like planets around main-sequence M-type stars (spectral types M0 to M5). The detection of planets around M dwarfs is the royal road to allow an early characterisation of telluric planets with the JWST or ELT. The upgrade of SOPHIE in 2011 brought new possibilities to this program, allowing it to perform high-precision radial velocity measurements. In this talk, we will describe sub-programme 3, its target sample, observing strategy, and current status. we will also report on recent detections of low-mass planets issued from this programme, and discuss future directions the research programme could take in the context of new near-IR spectrographs such as SPIRou.

Compact planetary systems, where several planets are in or close to resonance have been detected by transit surveys. This class of systems includes Kepler-11, Kepler-80, K2-138 or TRAPPIST-1, which offer insights on formation processes. Unfortunately, the host stars are too faint for precise, direct measurements of planetary masses with radial velocities. The first detection of a near-resonant system with radial velocities has been made thanks to SOPHIE spectroscopic measurements: the HD 158259 system, with five to six planets in a near 3:2 mean motion resonance chain. In this talk, we will present an overview of the new data analysis methods that allowed the detection, and highlight the scientific impact of this discovery.

We present the discovery and characterization of a transiting sub-Neptune orbiting with a 16.20-days period around a nearby (28 pc) and bright (V= 8.37) K0V star HD207897 (TOI-1611). This discovery is based on photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission and radial velocity (RV) observations from the SOPHIE, Automated Planet Finder (APF) and HIRES high precision spectrographs. We used EXOFASTv2 for simultaneously modeling the parameters of the planet and its host star, combining photometry and RVs data to determine the planetary system parameters. We show that the planet has a radius of 2.50 ± 0.08 RE and mass of either 14.4 ± 1.6 ME or 15.9 ± 1.6 ME with nearly equal probability; the two solutions correspond to two possibilities for the stellar activity period. Hence, density is either 5.1 ± 0.7 g cm−3 or 5.5 ±0.8 g cm−3, making it one of the relatively rare dense sub-Neptunes. The existence of such a dense planet at only 0.12 AU from its host star is unusual in the currently observed sub-Neptune (2 < RE < 4) population, and may reflect an interesting history of the system formation and evolution. The most likely scenario is that this planet has migrated to its current position."

Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplanets detected thanks to radial velocity (RV) variations of their host star, as performed at OHP/T193 with SOPHIE, still lack a measurement of their true mass. For those, only the minimum mass, or m sin(i), is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane-of-the-sky. The derived mass is generally that of an assumed edge-on system (90 degrees). But many other inclinations are likely, even extreme values closer to 0 degree (face-on configuration). In such case, the mass of the companion could be strongly underestimated, possibly up to few orders of magnitude. I recently developed a tool, called GASTON (Kiefer et al. 2019; Kiefer 2019; Kiefer et al. 2021), in order to take advantage of the voluminous Gaia astrometric database for constraining the inclination and true mass of exoplanet candidates. This tool uses the DR1 "astrometric excess noise" as an astrometric signature of the source photocenter orbit due to the presence of the detected companion. Based on the RV orbit parameters, I find the orbital inclination of the companion by matching astrometric simulations to the published DR1 astrometric excess noise. In this presentation, I will present the GASTON method and report on several exoplanet candidates reclassified in the stellar domain, among which unknown brown/M-dwarf. I will show how masses derived by RVs could be subject to strong underestimations, and how Gaia is already useful - and will be even more useful in the near future - to solve these degeneracies. 

We report the detection and characterization of the new transiting extrasolar planet TOI-1710b. It was first identified as a promising candidate by the Transiting Exoplanet Survey Satellite (TESS). Its planetary nature has been established from SOPHIE and HARPS-N spectroscopic observations via the radial velocity method. The stellar parameters for the host star are derived from the spectra and a joint Markov chain Monte Carlo (MCMC) adjustment of the spectral energy distribution and evolutionary tracks of TOI-1710. Performed in a combined MCMC and quasi-periodic Gaussian process method, a simultaneous analysis of the TESS light curve and the radial velocity evolution concomitantly allows us  to determine the planetary properties and inspect the stellar magnetic activity jitter. TOI-1710b is a massive Neptune (31.8±5.9 M_Earth and 5.84±0.30 R_Earth) orbiting a G5VI subdwarf star on a 24.3 days almost circular orbit (e=0.14±0.08).

Présentation de la situation actuelle sur le T193, mode de fonctionnement, ressources humaines et support aux observations.

To test models of the formation and evolution of galaxies and as a reference sample for the studies of the properties of galaxies in pairs, groups, and clusters is needed to study a representative sample of isolated galaxies, in order to understand the effects of the environment on fundamental galactic properties. We selected a sample of edge-on galaxies (i ≥ 80) from the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973) to characterise their Hα emitting gas kinematics. Edge-on galaxies can offer important insight into galaxy evolution because they are the only systems where the distribution of the different components can be studied both radially and vertically. We observed them using the scanning Fabry-Perot interferometer, GHASP, attached at the Cassegrain focus at the 1.93m telescope at the Observatoire de Haute-Provence. Since the disk is better appreciated from its stellar emission, we used WISE photometric data in the W1-band (3.4 μm) to define the galactic disk. Comparing with the stellar galactic disk, we detected galaxies with Hα emitting gas radially extended, truncated Hα disks or very diffuse Hα disks. In addition, by inspection, we have found multiple emission-profiles in clouds with high dispersion velocity that sign shocks or gas in expansion from mechanical feedback mechanisms, such as supernovae-driven or past active-galactic-nuclei-driven out-flows, which are the most relevant events in reference to the origin of a spiral galaxy’s halo gas. Nevertheless, other origins include tidal interaction that likely took part 1-2 Gyr ago.

Authors: Stephen Marsden¹ and Coralie Neiner²

(1): University of Southern Queensland, Australia.
(2): LESIA, Observatoire de Paris, France.

Magnetic fields are one of the main drivers of the evolution of solar-type stars. They affect everything from the rotational evolution of the star through to the habitability of orbiting exoplanets. In this project we are attempting to help understand how the magnetic dynamos of young Suns evolve from chaotic variability to the regular magnetic cycles that we see on our own Sun today. To do this in 2018 we started a monitoring campaign using (NEO)NARVAL on TBL to observe five of the brightest young Suns in the night sky. We have so far obtained 2 - 3 epochs of spectropolarimetric data on each of our targets and from these have created preliminary maps of the stellar magnetic topologies. In this talk we present some of the initial results from this magnetic mapping and compare them to previous observations of these stars to look for long-term trends that may indicate developing cycles.

We report on observations of the active K2 dwarf ɛ Eridani based on contemporaneous SPIRou, NARVAL and TESS data obtained over two months in late 2018, when the activity of the star was reported to be in a non-cyclic phase. Fundamental parameters of ɛ Eridani derived from visible and NIR wavelengths provide us with consistent results, which also agree with published values. Zeeman broadening of individual lines highlights an unsigned surface magnetic field B = 1.90 ± 0.13 kG, with a filling factor f = 12.5 ± 1.7% (unsigned magnetic flux Bf = 237 ± 36 G). The large-scale magnetic field geometry, chromospheric emission and broadband photometry display clear signs of non-rotational evolution over the course of data collection. Characteristic decay times deduced from the light curve and longitudinal field fall in the range 30-40 days, while the characteristic timescale of surface differential rotation, as derived through the evolution of the magnetic geometry, is equal to 57 ± 5 days. The large-scale magnetic field exhibits a combination of properties not observed previously for ɛ Eridani, with a surface field among the weakest previously reported, but this field is also mostly axisymmetric, and is dominated by a toroidal component.

Une étude d’un suivi spectropolarimétrique de cette étoile T Tauri classique de masse intermédiaire a révélé une vitesse radiale suspecte, bien en deçà de la vitesse médiane de la région du Taureau
dont elle fait partie. De plus, la courbe de vitesse radiale sur 14 jours montre, en plus d’une modulation induite par une tache à la surface, une légère pente décroissante.
La prospection de données passées, ainsi que l’acquisition ponctuelle deux 2 spectres par des collaborateurs ont révélé une vitesse radiale variant entre 7 et 20 km/s. Cela nous a mené à suspecter la présence d’un compagnon, non visible sur les spectres, influant sur la vitesse radiale systémique de HQ Tauri. Ces travaux sont publiés dans A&A (Pouilly et al., 2020).
Ces résultats nous ont mené à demander des observations additionnelles avec 4 spectromètres : SPIRou et ESPaDOnS au CFHT, Neo-Narval au TBL et Sophie à l’OHP.
Le but de cette campagne multi-outils est de croiser les nuits d’observations avec les différents télescopes afin d’obtenir une courbe de vitesse radiale sur la durée d’un semestre d’observation
complet. Le challenge réside dans l’exploitation des 4 jeux de données de manière à améliorer les mesures à petite échelle tout en gardant un échantillonnage suffisant pour évaluer la modulation à
grande échelle induite par le potentiel compagnon, en prenant en compte la modulation non négligeable induite par la tache de surface.