A5028163484- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Scientific Research and Discoveries
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Planetary Science and Exploration
- Particle Accelerators and Free-Electron Lasers
- Photocathodes and Microchannel Plates
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Chemical Thermodynamics and Molecular Structure
- Particle accelerators and beam dynamics
- High-pressure geophysics and materials
- Spacecraft Dynamics and Control
- Geomagnetism and Paleomagnetism Studies
- Advanced Semiconductor Detectors and Materials
- Atmospheric and Environmental Gas Dynamics
University of Geneva
2015-2024
Observatoire Cantonal de Neuchâtel
2024
University of Bern
2015-2021
Global Social Observatory
2020
Instituto de Astrofísica de Canarias
2020
ESPRESSO is the new high-resolution spectrograph of ESO's Very-Large Telescope (VLT). It was designed for ultra-high radial-velocity precision and extreme spectral fidelity with aim performing exoplanet research fundamental astrophysical experiments unprecedented accuracy. able to observe any four Unit Telescopes (UT) VLT at a resolving power 140,000 or 190,000 over 378.2 788.7 nm wavelength range, all UTs together, turning into 16-m diameter equivalent telescope in terms collecting area,...
Context. KELT-9 b exemplifies a newly emerging class of short-period gaseous exoplanets that tend to orbit hot, early type stars – termed ultra-hot Jupiters. The severe stellar irradiation heats their atmospheres temperatures ~4000 K, similar photospheres dwarf stars. Due the absence aerosols and complex molecular chemistry at such temperatures, these planets offer potential detailed chemical characterization through transit day-side spectroscopy. Detailed studies inventories may provide...
Determining the architecture of multi-planetary systems is one cornerstones understanding planet formation and evolution. Resonant are especially important as fragility their orbital configuration ensures that no significant scattering or collisional event has taken place since earliest phase when parent protoplanetary disc was still present. In this context, TOI-178 been subject particular attention first TESS observations hinted at a 2:3:3 resonant chain. Here we report results from...
We present the open-source radiative transfer code named HELIOS, which is constructed for studying exoplanetary atmospheres. In its initial version, model atmospheres of HELIOS are one-dimensional and plane-parallel, equation solved in two-stream approximation with nonisotropic scattering. A small set main infrared absorbers employed, computed opacity calculator HELIOS-K combined using a correlated-k approximation. The molecular abundances originate from validated analytical formulae...
Aims: We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution, elaborate on existing interpretations optical observed with HST/STIS WFC3. Methods: use cross-correlation technique direct differential spectroscopy to search sodium other neutral ionised atoms, TiO, VO SH in high-resolution transit spectra obtained HARPS spectrograph. inject models assuming chemical hydrostatic equilibrium varying temperature composition enable...
We present the first detection of atomic emission lines from atmosphere an exoplanet. detect neutral iron day-side KELT-9b (Teq $\sim$ 4, 000 K). combined thousands spectrally resolved observed during one night with HARPS-N spectrograph (R 115, 000), mounted at Telescopio Nazionale Galileo. introduce a novel statistical approach to extract planetary parameters binary mask cross-correlation analysis. also adapt concept contribution function context high spectral resolution observations,...
We aim to confirm the presence of Proxima b using independent measurements obtained with new ESPRESSO spectrograph, and refine planetary parameters taking advantage its improved precision. analysed 63 spectroscopic observations taken during 2019. radial velocity a typical photon noise 26 cm/s. ran joint MCMC analysis on time series full-width half maximum cross-correlation function model stellar signals present in data, applying Gaussian process regression deal activity. independently data....
High-resolution optical spectroscopy is a powerful tool to characterise exoplanetary atmospheres from the ground. The sodium D lines, with their large cross sections, are especially suited study upper layers of in this context. We report on results HEARTS, spectroscopic survey exoplanet atmospheres, performing comparative hot gas giants determine effects stellar irradiation. In second installation series, we highlight detection neutral ultra-hot giant WASP-76b. observed three transits planet...
High-resolution optical spectroscopy during the transit of HD 189733b, a prototypical hot Jupiter, allowed resolution Na I D sodium lines in planet, giving access to extreme conditions planet upper atmosphere. We have undertaken HEARTS, spectroscopic survey exoplanet atmospheres, perform comparative study gas giants and determine how stellar irradiation affect them. Here, we report on first HEARTS observations Saturn-mass WASP-49b. observed with HARPS high-resolution spectrograph at ESO 3.6m...
The substellar companion HD206893b has recently been discovered by direct imaging of its disc-bearing host star with the SPHERE instrument. We investigate atypical properties companion, which reddest near-infrared colours among all known objects, either orbiting a or isolated, and we provide comprehensive characterisation star-disc-companion system. conducted follow-up adaptive optics spectro-imaging SPHERE, multiinstrument star. obtain R=30 spectrum from 0.95 to 1.64 micron additional...
Ultra-hot Jupiters offer interesting prospects for expanding our theories on dynamical evolution and the properties of extremely irradiated atmospheres. In this context, we present analysis new optical spectroscopy transiting ultra-hot Jupiter WASP-121b. We first refine orbital WASP-121b, which is a nearly polar (obliquity $ψ^{\rm North}$=88.1$\pm$0.25$^{\circ}$ or South}$=91.11$\pm$0.20$^{\circ}$) orbit, exclude high differential rotation its fast-rotating (P$
Directly imaged planets and substellar companions are key targets for the characterization of self-luminous atmospheres. Their photometric appearance at 4-5 $μ$m is sensitive to chemical composition cloud content their atmosphere. We aim systematically characterizing atmospheres directly low-mass $μ$m. want homogeneously process data compile a library thermal wavelengths these mostly young, low-gravity objects. In this way, we find trends related spectral type surface gravity by comparing...
The advent of a new generation radial velocity instruments has allowed us to break the one Earth-mass barrier. We report milestone in this context with detection lowest-mass planet measured so far using velocities: L 98-59 b, rocky half mass Venus. It is part system composed three known transiting terrestrial planets (planets b d). announce discovery fourth nontransiting minimum 3.06_{-0.37}^{+0.33} MEarth and an orbital period 12.796_{-0.019}^{+0.020} days indications for presence fifth...
We report on precise Doppler measurements of L231-32 (TOI-270), a nearby M dwarf ($d=22$ pc, $M_\star = 0.39$ M$_\odot$, $R_\star 0.38$ R$_\odot$), which hosts three transiting planets that were recently discovered using data from the Transiting Exoplanet Survey Satellite (TESS). The are 1.2, 2.4, and 2.1 times size Earth have orbital periods 3.4, 5.7, 11.4 days. obtained 29 high-resolution optical spectra with newly commissioned Echelle Spectrograph for Rocky Stable Spectroscopic...
We observed two transits of the iconic gas giant HD 209458b between 380 and 780 nm, using high-resolution ESPRESSO spectrograph. The derived planetary transmission spectrum exhibits features at all wavelengths where parent star shows strong absorption lines, for example, NaI, MgI, FeI, FeII, CaI, VI, H$\alpha$, KI. interpreted these as signature deformation stellar line profiles due to Rossiter-McLaughlin effect, combined with centre-to-limb effects on surface, which is in agreement similar...
The distribution of close-in exoplanets is shaped by a complex interplay between atmospheric and dynamical processes. Desert-Rim Exoplanets Atmosphere Migration (DREAM) program aims at disentangling those processes through the study hot Neptune desert, whose rim hosts planets that are undergoing, or survived, evaporation orbital migration. In this first paper, we use Rossiter-McLaughlin revolutions (RMR) technique to investigate architecture 14 ranging from mini-Neptune Jupiter-size covering...
Abstract We present an open-source retrieval code named HELIOS–RETRIEVAL , designed to obtain chemical abundances and temperature–pressure profiles by inverting the measured spectra of exoplanetary atmospheres. In our forward model, we use exact solution radiative transfer equation, in pure absorption limit, which allows us analytically integrate over all outgoing rays. Two chemistry models are considered: unconstrained equilibrium (enforced via analytical formulae). The nested sampling...
Context. The atmosphere of exoplanets has been studied extensively in recent years, making use numerical models to retrieve chemical composition, dynamical circulation, or temperature from the data. One best observational probes transmission is sodium doublet thanks its extensive cross-section. However, modelling shape planetary lines proven be challenging. Models with different assumptions regarding have employed fit literature, yet statistically-sound, direct comparisons are needed paint a...
The study of exoplanet atmospheres is essential to understand the formation, evolution and composition exoplanets. transmission spectroscopy technique playing a significant role in this domain. In particular, combination state-of-the-art spectrographs at low- high-spectral resolution key our understanding atmospheric structure composition. Two transits close-in sub Saturn-mass planet,WASP-127b, have been observed with ESPRESSO frame Guaranteed Time Observations Consortium. Transit...
Context. Small planets located at the lower mode of bimodal radius distribution are generally assumed to be composed iron and silicates in a proportion similar that Earth. However, recent discoveries revealing new group low-density inconsistent with description. Aims. We intend confirm characterize TESS planet candidate TOI-244.01, which orbits bright ( K = 7.97 mag), nearby d 22 pc), early-type (M2.5 V) M-dwarf star GJ 1018 an orbital period 7.4 days. Methods. used Markov chain Monte Carlo...
GJ 9827 is a bright, nearby K7V star orbited by two super-Earths and one mini-Neptune on close-in orbits. The system was first discovered using K2 data then further characterized other spectroscopic photometric instruments. Previous literature studies provide several mass measurements for the three planets, however, with large variations uncertainties. To better constrain planetary masses, we added high-precision radial velocity from ESPRESSO to published datasets HARPS, HARPS-N, HIRES...