Valentin Christiaens
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View article: Exomoon search with VLTI/GRAVITY around the substellar companion HD 206893 B
Exomoon search with VLTI/GRAVITY around the substellar companion HD 206893 B Open
Direct astrometric detection of exomoons remains unexplored. This study presents the first application of high-precision astrometry to search for exomoons around substellar companions. We investigate whether the orbital motion of the compa…
View article: Constraints on the Orbit of the Young Substellar Companion GQ Lup B from High-resolution Spectroscopy and VLTI/GRAVITY Astrometry <sup>*</sup>
Constraints on the Orbit of the Young Substellar Companion GQ Lup B from High-resolution Spectroscopy and VLTI/GRAVITY Astrometry <sup>*</sup> Open
Understanding the orbits of giant planets is critical for testing planet formation models, particularly at wide separations (>10 au) where traditional core accretion becomes inefficient. However, constraining orbits at these separations ha…
View article: The ExoGRAVITY survey: A K-band spectral library of giant exoplanet and brown dwarf companions
The ExoGRAVITY survey: A K-band spectral library of giant exoplanet and brown dwarf companions Open
Direct observations of exoplanet and brown dwarf companions with near-infrared interferometry, first enabled by the dual-field mode of VLTI/GRAVITY, provide unique measurements of the objects' orbital motions and atmospheric compositions. …
View article: Erratum: “MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind toward SY Cha” (2025, ApJ, 980, 148)
Erratum: “MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind toward SY Cha” (2025, ApJ, 980, 148) Open
View article: MINDS: The very low-mass star and brown dwarf sample
MINDS: The very low-mass star and brown dwarf sample Open
Context . Disks around very low-mass stars (VLMSs) provide environments for the formation of Earth-like planets. Mid-infrared observations have revealed that these disks often exhibit weak silicate features and prominent hydrocarbon emissi…
View article: Constraints on the Orbit of the Young Substellar Companion GQ Lup B from High-Resolution Spectroscopy and VLTI/GRAVITY Astrometry
Constraints on the Orbit of the Young Substellar Companion GQ Lup B from High-Resolution Spectroscopy and VLTI/GRAVITY Astrometry Open
Understanding the orbits of giant planets is critical for testing planet formation models, particularly at wide separations greater than 10 au where traditional core accretion becomes inefficient. However, constraining orbits at these sepa…
View article: MINDS
MINDS Open
Context. The chemistry of disks around brown dwarfs (BDs) remains largely unexplored due to their faintness. Despite the efforts performed with Spitzer, we have far less understanding of planet formation, chemical composition, disk structu…
View article: MINDS: A transition from H<sub>2</sub>O to C<sub>2</sub>H<sub>2</sub> dominated disk spectra with decreasing stellar luminosity
MINDS: A transition from H<sub>2</sub>O to C<sub>2</sub>H<sub>2</sub> dominated disk spectra with decreasing stellar luminosity Open
Context . The chemical composition of the inner regions of disks around young stars will largely determine the properties of planets that form in these regions. Many physical processes in the disks drive their chemical evolution, and some …
View article: MINDS: Detection of an Inner Gas Disk Caused by Evaporating Bodies around HD 172555
MINDS: Detection of an Inner Gas Disk Caused by Evaporating Bodies around HD 172555 Open
Mechanisms such as collisions of rocky bodies or cometary activity give rise to dusty debris disks. Debris disks trace the leftover building blocks of planets, and thus also planetary composition. HD 172555, a stellar twin of β Pic, hosts …
View article: Reliability of 1D radiative-convective photochemical-equilibrium retrievals on transit spectra of WASP-107b
Reliability of 1D radiative-convective photochemical-equilibrium retrievals on transit spectra of WASP-107b Open
Context . WASP-107b has been observed in unprecedented detail with the James Webb Space Telescope. These observations suggest that it has a metal-rich and carbon-deprived atmosphere with an extremely hot interior based on detections of SO …
View article: Direct imaging discovery of a young giant planet orbiting on Solar System scales
Direct imaging discovery of a young giant planet orbiting on Solar System scales Open
HD 135344 AB is a young visual binary system that is best known for the protoplanetary disk around the secondary star. The circumstellar environment of the A0-type primary star, on the other hand, is already depleted. HD 135344 A is theref…
View article: Orbit and atmosphere of HIP 99770 b through the eyes of VLTI/GRAVITY
Orbit and atmosphere of HIP 99770 b through the eyes of VLTI/GRAVITY Open
Context: Inferring the likely formation channel of giant exoplanets and brown dwarf companions from orbital and atmospheric observables remains a formidable challenge. Further and more precise directly measured dynamical masses of these co…
View article: Orbit and atmosphere of HIP 99770 b through the eyes of VLTI/GRAVITY
Orbit and atmosphere of HIP 99770 b through the eyes of VLTI/GRAVITY Open
Context . Inferring the likely formation channel of giant exoplanets and brown dwarf companions from orbital and atmospheric observables remains a formidable challenge. Further and more precise directly measured dynamical masses of these c…
View article: MINDS: The very low-mass star and brown dwarf sample. Detections and trends in the inner disk gas
MINDS: The very low-mass star and brown dwarf sample. Detections and trends in the inner disk gas Open
Planet-forming disks around brown dwarfs and very low-mass stars (VLMS) are, on average, less massive and are expected to undergo faster radial solid transport than their higher-mass counterparts. Spitzer had detected C_2H_2 CO_2 and HCN a…
View article: MINDS: The Very Low-mass Star and Brown Dwarf Sample Hidden Water in Carbon-dominated Protoplanetary Disks
MINDS: The Very Low-mass Star and Brown Dwarf Sample Hidden Water in Carbon-dominated Protoplanetary Disks Open
Infrared observations of the inner disks around very low-mass stars (VLMS; <0.3 M ⊙ ) have revealed a carbon-rich gas composition in the terrestrial planet-forming regions. Contrary to the typically water-rich T Tauri disk spectra, only tw…
View article: Dust populations from 30 to 1000 au in the debris disk of HD 120326
Dust populations from 30 to 1000 au in the debris disk of HD 120326 Open
Context. To date, more than a hundred debris disks have been spatially resolved. Among them, the young system HD 120326 stands out, displaying different disk substructures on both intermediate (30–150 au) and large (150–1000 au) scales. Ai…
View article: Differentiating formation models with new dynamical masses for the PDS 70 protoplanets
Differentiating formation models with new dynamical masses for the PDS 70 protoplanets Open
Hot- and cold-start planet formation models predict differing luminosities for the young, bright planets that direct-imaging surveys are most sensitive to. However, precise mass estimates are required to distinguish between these models ob…
View article: Dust populations from 30 to 1000 au in the debris disk of HD 120326
Dust populations from 30 to 1000 au in the debris disk of HD 120326 Open
Context. To date, more than a hundred debris disks have been spatially resolved. Among them, the young system HD 120326 stands out, displaying different disk substructures on both intermediate (30-150 au) and large (150-1000 au) scales. Ai…
View article: MINDS. Anatomy of a water-rich, inclined, brown dwarf disk: lack of abundant hydrocarbons
MINDS. Anatomy of a water-rich, inclined, brown dwarf disk: lack of abundant hydrocarbons Open
2MASS J04381486+2611399 (or J0438) is one of the few young brown dwarfs (BD) with a highly inclined ($i\!\sim\!70^\circ$) disk. Here we report results from JWST-MIRI MRS, HST-ACS and ALMA Band 7 observations. Despite its late spectral type…
View article: Keplerian motion of a compact source orbiting the inner disc of PDS 70: a third protoplanet in resonance with b and c?
Keplerian motion of a compact source orbiting the inner disc of PDS 70: a third protoplanet in resonance with b and c? Open
The disc around PDS 70 hosts two directly imaged protoplanets in a gap. Previous VLT/SPHERE and recent JWST/NIRCam observations have hinted at the presence of a third compact source in the same gap at $\sim$13 au, interior to the orbit of …
View article: The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. III. Aperture Masking Interferometric Observations of the Star HIP 65426 at 3.8 <i>μ</i>m
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. III. Aperture Masking Interferometric Observations of the Star HIP 65426 at 3.8 <i>μ</i>m Open
We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μ m, as part of the JWST Direct Imaging Early Release Science program, obtained using the Near Infrared Imager and Slitless Spectrograph instrument.…
View article: Use the 4S (Signal-Safe Speckle Subtraction): Explainable Machine Learning Reveals the Giant Exoplanet AF Lep b in High-contrast Imaging Data from 2011
Use the 4S (Signal-Safe Speckle Subtraction): Explainable Machine Learning Reveals the Giant Exoplanet AF Lep b in High-contrast Imaging Data from 2011 Open
The main challenge of exoplanet high-contrast imaging (HCI) is to separate the signal of exoplanets from their host stars, which are many orders of magnitude brighter. HCI for ground-based observations is further exacerbated by speckle noi…
View article: MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind toward SY Cha
MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind toward SY Cha Open
The removal of angular momentum from protostellar systems drives accretion onto the central star and may drive the dispersal of the protoplanetary disk. Winds and jets can contribute to removing angular momentum from the disk, though the d…
View article: Anatomy of a fall: stationary and super-Keplerian spiral arms generated by accretion streamers in protostellar discs
Anatomy of a fall: stationary and super-Keplerian spiral arms generated by accretion streamers in protostellar discs Open
Late-stage infall onto evolved protoplanetary discs is an important source of material and angular momentum replenishment and disc substructures. In this paper, we used 3D smoothed particle hydrodynamics simulations to model streamer–disc …
View article: MINDS: JWST/NIRCam imaging of the protoplanetary disk PDS 70
MINDS: JWST/NIRCam imaging of the protoplanetary disk PDS 70 Open
Contains fulltext : 316490.pdf (Publisher’s version ) (Open Access)
View article: MINDS. JWST-MIRI reveals a peculiar CO<sub>2</sub>-rich chemistry in the drift-dominated disk CX Tau
MINDS. JWST-MIRI reveals a peculiar CO<sub>2</sub>-rich chemistry in the drift-dominated disk CX Tau Open
Context . Radial drift of icy pebbles can have a large impact on the chemistry of the inner regions of protoplanetary disks, where most terrestrial planets are thought to form. Disks with compact millimeter dust emission (≲50 au) are sugge…
View article: Direct imaging discovery of a young giant planet orbiting on Solar System scales
Direct imaging discovery of a young giant planet orbiting on Solar System scales Open
Contains fulltext : 321440.pdf (Publisher’s version ) (Open Access)
View article: MINDS. JWST-MIRI reveals a peculiar CO$_2$-rich chemistry in the drift-dominated disk CX Tau
MINDS. JWST-MIRI reveals a peculiar CO$_2$-rich chemistry in the drift-dominated disk CX Tau Open
Radial drift of icy pebbles can have a large impact on the chemistry of the inner regions of protoplanetary disks. Compact dust disks ($\lesssim$50 au) are suggested to have a higher (cold) H$_2$O flux than more extended disks, likely due …
View article: An alternating minimization algorithm with trajectory for direct exoplanet detection
An alternating minimization algorithm with trajectory for direct exoplanet detection Open
Context . Effective image post-processing algorithms are vital for the successful direct imaging of exoplanets. Standard point spread function (PSF) subtraction methods use techniques based on a low-rank approximation to separate the rotat…
View article: Anatomy of a Fall: Stationary and super-Keplerian spiral arms generated by accretion streamers in protostellar discs
Anatomy of a Fall: Stationary and super-Keplerian spiral arms generated by accretion streamers in protostellar discs Open
Late-stage infall onto evolved protoplanetary discs is an important source of material and angular momentum replenishment, and disc substructures. In this paper we used 3D smoothed particle hydrodynamics simulations to model streamer-disc …