A5083285161- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- Planetary Science and Exploration
- Scientific Research and Discoveries
- High-pressure geophysics and materials
- Space Exploration and Technology
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Astronomical and nuclear sciences
- Spacecraft and Cryogenic Technologies
- Photocathodes and Microchannel Plates
- History and Developments in Astronomy
- Spaceflight effects on biology
- Nuclear physics research studies
- Dark Matter and Cosmic Phenomena
- Superconducting Materials and Applications
University of Geneva
2016-2025
Université de Montréal
2024
Global Social Observatory
2023
University of Colorado Boulder
2020
Centre National de la Recherche Scientifique
2012-2018
Institut d'Astrophysique de Paris
2012-2018
Observatoire Cantonal de Neuchâtel
2018
Laboratoire AstroParticule et Cosmologie
2016-2017
Sorbonne Université
2012-2014
Laboratoire de Météorologie Physique
2010
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...
Transit observations in Ly-alpha of HD209458b and HD189733b revealed signatures neutral hydrogen escaping the planets. We present a 3D particle model dynamics atoms, calculate theoretical absorption line profiles, which can be directly compared with observed blue wing line. For velocities atoms up to -130km/s are naturally explained by radiation-pressure acceleration. The well-fitted an ionizing flux about 3-4 times solar escape rate range 10^9-10^11g/s, agreement predictions. was 2011...
The warm Neptune GJ436b was observed with HST/STIS at three different epochs in the stellar Ly-alpha line, showing deep, repeated transits caused by a giant exosphere of neutral hydrogen. low radiation pressure from M-dwarf host star shown to play major role dynamics escaping gas. Yet itself it cannot explain time-variable spectral features detected each transit. Here we investigate combined radiative braking and wind interactions using numerical simulations EVaporating Exoplanet code (EVE)...
Atmospheric escape has been detected from the exoplanet HD 209458b through transit observations of hydrogen Lyman-alpha line. Here we present spectrally resolved 189733b at two different epochs. These HST/STIS show for first time, that there are significant temporal variations in physical conditions an evaporating planetary atmosphere. While atmospheric is not epoch observations, it observed second epoch, producing a absorption depth 14.4+/-3.6% between velocities -230 to -140 km/s. Contrary...
When a planet transits its host star, it blocks regions of the stellar surface from view; this causes distortion spectral lines and change in line-of-sight (LOS) velocities, known as Rossiter-McLaughlin (RM) effect. Since LOS velocities depend, part, on rotation, RM waveform is sensitive to star-planet alignment (which provides information system's dynamical history). We present new modelling technique that directly measures spatially-resolved spectrum behind planet. This done by scaling...
The naked-eye star 55 Cancri hosts a planetary system with five known planets, including hot super-Earth (55 Cnc e) extremely close to its and farther out giant planet b), found in milder irradiation conditions respect other Jupiters. This raises important questions on the evolution of atmospheres for close-in exoplanets, dependence mass irradiation. These can be addressed by Lyman-alpha transit observations extended hydrogen atmospheres, complemented contemporaneous measurements stellar...
Abstract We present an XMM–Newton X-ray observation of TRAPPIST-1, which is ultracool dwarf star recently discovered to host three transiting and temperate Earth-sized planets. find the a relatively strong variable coronal source with luminosity similar that quiet Sun, despite its much lower bolometric luminosity. LX/Lbol = 2–4 × 10−4, total XUV emission in range LXUV/Lbol 6–9 irradiation planets many times stronger than experienced by present-day Earth. Using simple energy-limited model, we...
We report new near ultraviolet HST/STIS observations of atmospheric absorptions during the planetary transit HD209458b. detect absorption in atomic magnesium (MgI), while no signal has been detected lines singly ionized (MgII). measure MgI to be 6.2+/-2.9% velocity range from -62 -19 km/s. The detection upper atmosphere at a distance several radii gives first view into transition region between thermosphere and exobase, where escape takes place. estimate electronic densities needed...
Observations of transits the hot giant exoplanet HD 189733b in unresolved HI Lyman-alpha line show signs hydrogen escaping upper atmosphere planet. New resolved observations obtained with STIS spectrograph onboard Hubble Space Telescope April 2010 and September 2011 confirmed that planet is evaporating, furthermore discovered significant temporal variations physical conditions its evaporating atmosphere. Here we present a detailed analysis 189733b, when an atmospheric signature was detected....
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...
WASP-121b is one of the most studied Ultra-hot Jupiters: many recent analyses its atmosphere report interesting features at different wavelength ranges. In this paper we analyze transit acquired with high-resolution spectrograph ESPRESSO VLT in 1-telescope mode, and partial taken during commissioning instrument 4-telescope mode. We investigate anomalous in-transit radial velocity curve study transmission spectrum planet. By analysing velocities were able to infer presence atmospheric...
Orbiting a bright, nearby star the 55 Cnc system offers rare opportunity to study multiplanet that has wide range of planetary masses and orbital distances. Using two decades photometry spectroscopy data, we have measured rotation host its solar-like magnetic cycle. Accounting for this cycle in our velocimetric analysis allows us revise properties outermost giant planet four companions. The innermost e is an unusually close-in super-Earth, whose transits allowed detailed follow-up studies....
The TRAPPIST-1 system offers the opportunity to characterize terrestrial, potentially habitable planets orbiting a nearby ultracool dwarf star. We performed four-orbit reconnaissance with Space Telescope Imaging Spectrograph onboard Hubble study stellar emission at Lyman-α, assess presence of hydrogen exospheres around two inner planets, and determine their UV irradiation. detect Lyman-α line TRAPPIST-1, making it coldest exoplanet host star for which this has been measured. reconstruct...
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...
Abstract The helium absorption triplet at a wavelength of 10833 Å has been proposed as way to probe the escaping atmospheres exoplanets. Recently this feature was detected for first time using Hubble Space Telescope ( HST ) WFC3 observations hot Jupiter WASP-107b. We use similar /WFC3 detect in atmosphere Neptune HAT-P-11b 4 σ confidence level. compare our grid 1D models hydrodynamic escape constrain thermospheric temperatures and mass loss rate. find that data are best fit by with high...
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}$) orbit, exclude high differential rotation its fast-rotating (P$
Helium escaping from hot gas giants Many giant exoplanets orbit so close to their host star that they are heated high temperatures, causing atmospheric gases escape. Gas atmospheres mostly hydrogen and helium, which difficult observe. Two papers have now observed helium in the near-infrared (see Perspective by Brogi). Allart et al. a Neptune-mass exoplanet performed detailed simulations of its atmosphere, put constraints on escape rate. Nortmann found is Saturn-mass planet, trailing behind...