N. Meunier
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View article: Chromaticity of stellar activity in radial velocities
Chromaticity of stellar activity in radial velocities Open
Context . In the search for exoplanets using radial velocities (RV), stellar activity has become one of the main limiting factors for detectability. Fortunately, activity-induced RV signals are wavelength-dependent or chromatic, unlike pla…
View article: Radial velocity homogeneous analysis of M dwarfs observed with HARPS
Radial velocity homogeneous analysis of M dwarfs observed with HARPS Open
Aims . We aim to re-determine planetary occurrences around M dwarfs using 20 years of observations from HARPS on 197 targets. The first aim of this study is to propose more precise occurrence rates using the large volume of the sample but …
View article: Measuring the Sun’s radial velocity variability due to supergranulation over a magnetic cycle.
Measuring the Sun’s radial velocity variability due to supergranulation over a magnetic cycle. Open
In recent years, supergranulation has emerged as one of the biggest challenges for the detection of Earth-twins in radial velocity planet searches. We used eight years of Sun-as-a-star radial velocity observations from HARPS-N to measure t…
View article: Measuring the Suns radial velocity variability due to supergranulation over a magnetic cycle
Measuring the Suns radial velocity variability due to supergranulation over a magnetic cycle Open
In recent years supergranulation has emerged as one of the biggest challenges for the detection of Earth-twins in radial velocity planet searches. We used eight years of Sun-as-a-star radial velocity observations from HARPS-N to measure th…
View article: Searching for substellar companion candidates with Gaia. III. Search for companions to members of young associations
Searching for substellar companion candidates with Gaia. III. Search for companions to members of young associations Open
Absolute astrometry with Gaia is expected to detect and characterize the orbits of thousands of exoplanets in the coming years. A tool, GaiaPMEX, was recently developed to characterize multiple systems based on Gaia-only data, and, when po…
View article: Investigating stellar activity through eight years of Sun-as-a-star observations
Investigating stellar activity through eight years of Sun-as-a-star observations Open
Stellar magnetic activity induces both distortions and Doppler-shifts in the absorption line profiles of Sun-like stars. Those effects produce apparent radial velocity (RV) signals which greatly hamper the search for potentially habitable,…
View article: Investigating stellar activity through eight years of Sun-as-a-star observations
Investigating stellar activity through eight years of Sun-as-a-star observations Open
Stellar magnetic activity induces both distortions and Doppler-shifts in the absorption line profiles of Sun-like stars. Those effects produce apparent radial velocity (RV) signals which greatly hamper the search for potentially habitable,…
View article: Confrontation between modelled solar integrated observables and direct observations I. Radial velocities and convective blueshift
Confrontation between modelled solar integrated observables and direct observations I. Radial velocities and convective blueshift Open
Stellar variability strongly impacts the search for low-mass exoplanets with radial velocity techniques. Two types of planet-free time series can be used to quantify this impact: models and direct solar observations after a subtraction of …
View article: Confrontation between modelled solar integrated observables and direct observations
Confrontation between modelled solar integrated observables and direct observations Open
Context . Stellar variability strongly impacts the search for low-mass exoplanets with radial velocity techniques. Two types of planet-free time series can be used to quantify this impact: models and direct solar observations after a subtr…
View article: Radial velocity homogeneous analysis of M dwarfs observed with HARPS
Radial velocity homogeneous analysis of M dwarfs observed with HARPS Open
Context. The census of planets around M dwarfs in the solar neighbourhood meets two challenges: detecting the best targets for the future characterisation of planets with ELTs, and studying the statistics of planet occurrence that are cruc…
View article: Characterisation of the stellar activity of M dwarfs. II. Relationship between Ca, H$α$, and Na chromospheric emissions
Characterisation of the stellar activity of M dwarfs. II. Relationship between Ca, H$α$, and Na chromospheric emissions Open
The chromospheric emission estimated in the core of different lines, such as Ca II H & K, Na D1 and D2, and Halpha, is not always correlated between lines, as the Ca II H & K and Halpha emission time series are anti-correlated for a few pe…
View article: Characterisation of the stellar activity of M dwarfs
Characterisation of the stellar activity of M dwarfs Open
Context. The chromospheric emission estimated in the core of different lines, such as Ca II H & K, Na D1 and D2, and Ha, is not always correlated between lines. In particular, the Ca II H & K and Ha emission time series are anti-correlated…
View article: The magnetically quiet solar surface dominates HARPS-N solar RVs during low activity
The magnetically quiet solar surface dominates HARPS-N solar RVs during low activity Open
Using images from the Helioseismic and Magnetic Imager aboard the \textit{Solar Dynamics Observatory} (SDO/HMI), we extract the radial-velocity (RV) signal arising from the suppression of convective blue-shift and from bright faculae and d…
View article: The magnetically quiet solar surface dominates HARPS-N solar RVs during low activity
The magnetically quiet solar surface dominates HARPS-N solar RVs during low activity Open
Using images from the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory, we extract the radial velocity (RV) signal arising from the suppression of convective blueshift and from bright faculae and dark sunspots transit…
View article: Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars
Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars Open
To detect Earth-mass planets using the Doppler method, a major obstacle is to differentiate the planetary signal from intrinsic stellar variability (e.g. pulsations, granulation, spots, and plages). Convective blueshift, which results from…
View article: Radial distribution of giant exoplanets at Solar System scales
Radial distribution of giant exoplanets at Solar System scales Open
Aims. Giant planets play a major role in multiple planetary systems. Knowing their demographics is important to test their overall impact on the formation of planetary systems. It is also important to test their formation processes. Recent…
View article: Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars
Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars Open
To detect Earth-mass planets using the Doppler method, a major obstacle is to differentiate the planetary signal from intrinsic stellar variability (e.g., pulsations, granulation, spots and plages). Convective blueshift, which results from…
View article: Activity time series of old stars from late F to early K
Activity time series of old stars from late F to early K Open
Context. Stellar variability impacts radial velocities (hereafter RVs) at various timescales and therefore the detectability of exoplanets and the mass determination based on this technique. Detecting and characterising Earth-like planets …
View article: Activity time series of old stars from late F to early K VI. Exoplanet mass characterisation and detectability in radial velocity
Activity time series of old stars from late F to early K VI. Exoplanet mass characterisation and detectability in radial velocity Open
Stellar variability impacts radial velocities at various timescales and therefore the detectability of exoplanets and the mass determination based on this technique. It is necessary to implement systematic studies, to delineate the current…
View article: Preparation for an unsupervised massive analysis of SPHERE high-contrast data with PACO
Preparation for an unsupervised massive analysis of SPHERE high-contrast data with PACO Open
Context. Despite tremendous progress in the detection and characterization of extrasolar planetary systems in the last 25 yr, we have not pinpointed any Solar System analogues. In particular, Jupiter-like planets (either mature or old) are…
View article: Preparing an unsupervised massive analysis of SPHERE high contrast data with the PACO algorithm
Preparing an unsupervised massive analysis of SPHERE high contrast data with the PACO algorithm Open
We aim at searching for exoplanets on the whole ESO/VLT-SPHERE archive with improved and unsupervised data analysis algorithm that could allow to detect massive giant planets at 5 au. To prepare, test and optimize our approach, we gathered…
View article: Impact of stellar variability on exoplanet detectability and characterisation
Impact of stellar variability on exoplanet detectability and characterisation Open
Stellar variability has become a major issue to detect low mass planets using the radial velocity technique. I present the approaches followed to characterise the amplitude and the properties of stellar variability in radial velocity. More…
View article: Linking the high-contrast performance with AO internal data and environmental parameters. Lessons learnt from the High Contrast Data Center and perspectives for the ELT
Linking the high-contrast performance with AO internal data and environmental parameters. Lessons learnt from the High Contrast Data Center and perspectives for the ELT Open
Adaptive Optics internal data include some information about environmental turbulence conditions and the actual wavefront incoming into the science detector. The High Contrast Data Center (HC-DC, previously named SPHERE Data Center) collec…
View article: Direct discovery of the inner exoplanet in the HD 206893 system
Direct discovery of the inner exoplanet in the HD 206893 system Open
Aims. HD 206893 is a nearby debris disk star that hosts a previously identified brown dwarf companion with an orbital separation of ∼10 au. Long-term precise radial velocity (RV) monitoring, as well as anomalies in the system proper motion…
View article: A HARPS radial velocity search for planets in the Scorpius-Centaurus association. And its combination with the HARPS and SOPHIE young nearby stars (YNS) surveys
A HARPS radial velocity search for planets in the Scorpius-Centaurus association. And its combination with the HARPS and SOPHIE young nearby stars (YNS) surveys Open
The Scorpius-Centaurus (Sco-Cen) young and nearby massive star-forming region is particularly well suited for extrasolar planet searches with both direct imaging and radial velocity (RV) techniques. The RV search, however, is challenging, …
View article: HARPS radial velocity search for planets in the Scorpius-Centaurus association
HARPS radial velocity search for planets in the Scorpius-Centaurus association Open
Context. The Scorpius-Centaurus (Sco-Cen) young and nearby massive star-forming region is particularly well suited for extrasolar planet searches with both direct imaging and radial velocity (RV) techniques. The RV search, however, is chal…
View article: Direct discovery of the inner exoplanet in the HD206893 system. Evidence for deuterium burning in a planetary-mass companion
Direct discovery of the inner exoplanet in the HD206893 system. Evidence for deuterium burning in a planetary-mass companion Open
Long term precise radial velocity (RV) monitoring of the nearby star HD206893, as well as anomalies in the system proper motion, have suggested the presence of an additional, inner companion in the system. Here we describe the results of a…
View article: Unsigned Magnetic Flux as a Proxy for Radial-velocity Variations in Sun-like Stars
Unsigned Magnetic Flux as a Proxy for Radial-velocity Variations in Sun-like Stars Open
A major obstacle to detecting and characterizing long-period, low-mass exoplanets is the intrinsic radial-velocity (RV) variability of host stars. To better understand RV variability, we estimate disk-averaged RV variations of the Sun over…
View article: High precision astrometry mission for the detection and characterization of nearby habitable planetary systems with the Nearby Earth Astrometric Telescope (NEAT)
High precision astrometry mission for the detection and characterization of nearby habitable planetary systems with the Nearby Earth Astrometric Telescope (NEAT) Open
(abridged) A complete census of planetary systems around a volume-limited sample of solar-type stars (FGK dwarfs) in the Solar neighborhood with uniform sensitivity down to Earth-mass planets within their Habitable Zones out to several AUs…
View article: Comité Exoplanètes Transverse : presentation and survey results
Comité Exoplanètes Transverse : presentation and survey results Open
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