Dino Mesa

We present high-contrast imaging observations of seven stars obtained with the Keck/NIRC2 vortex coronagraph between 2018 May and June in the L ′ and M _s bands. All targets host protoplanetary disks with substructures such as gaps and cavities, potentially tracing ongoing planet formation. Our aim is to assess whether these embedded planets can be directly detected. We reduced the observations with a custom pipeline based on the VIP Python package. Postprocessed images were obtained using angular differential imaging and reference differential imaging combined with principal component analysis. Finally, 5 σ contrast curves and detection limits were derived for all targets. We confirm the planetary candidate around Elias 2-24, previously proposed in the literature, at a separation of 394 ± 31 mas (54.9 ± 4.3 au) and a position angle of 298 . ° 8 ± 3 . ° 2, within the narrow gap of the protoplanetary disk. Comparing the derived photometry with 1 Myr isochrones, we infer a mass between 1.9 and 4.0 M _Jup for Elias 2-24 b, without considering accretion effects, in agreement with estimates considering the properties of the gap and planet–disk interactions. For all the systems in the survey, the 5 σ detection limits reach sensitivities down to 1–11 M _Jup at separations ≳0 . ″ 25. Since Elias 2-24 b (age ≲1 Myr) is the youngest exoplanet discovered to date, its confirmation has important implications for planet formation timescales and the origin of the gaps observed in very young disks.

Over the past decade, advances in high-contrast imaging instrumentation, coupled with extreme adaptive optics systems, have enabled the discovery of tens of planets and brown dwarfs orbiting at wide separations from their host stars (a ≳ 10, au). The existence of companions at these separations challenges current planet-formation paradigms, highlighting the importance of high-contrast imaging as the only technique capable of directly probing this region of planetary systems. In this paper, we present a survey of thirteen planets and brown dwarfs observed with VLT/SPHERE between June 2023 and July 2025. These data provide updated photometry in the 1.0–1.7, μm range and new high-precision astrometry, enabling tighter constraints on their orbital properties. We used the IRDIS subsystem to acquire dual-band H2H3 images (λ_ H2 = 1.593, μm, H3 = 1.667, μm) for all companions in our sample. For the three objects located within the IFS field of view (GQ Lup B, PZ Tel B, and HD 984 B), we additionally obtained low-resolution (R ∼ 50) near-infrared (0.96–1.34, μm) spectra. We combined our new astrometric measurements with those available in the literature to derive updated orbital solutions. The orbital fitting was performed using the orbitize! Python package. For CT Cha b, HIP 78530 B, HIP 64892 B, and RX J1609.5–2105 b, this work provides the first orbital solutions to date. We derived new photometry for all objects, which, when compared with field dwarfs in color–magnitude diagrams, indicates spectral types ranging from mid-M to mid-L. For the companions observed with IFS, their spectra are best matched by those of M6–M8.5 field dwarfs. Our updated orbital fits provide tighter constraints for nearly all companions and are consistent with non-circular orbits in all cases, potentially disfavoring core-accretion formation within their circumstellar disks.

Context . Unbiased surveys of large stellar samples are the prime means through which the prevalence of exoplanets can be derived, and crucial constraints to planet formation models can be set. Direct imaging (DI) is ideally positioned to probe the outer regions (5–300 au) of planetary systems, providing complementary information to techniques such as transits and radial velocities. Aims . We present the full sample of the SpHere INfrared survey for Exoplanets (SHINE), the second largest DI campaign to date. SHINE observed 460 stars between 2015 and 2023 thanks to the guaranteed time observations (GTO) allocated by ESO to the SPHERE consortium at VLT. The goal of this paper is to homogeneously derive the stellar properties of the targets and to define a subsample of young single hosts to be used as a starting point for the final statistical analysis of the survey. Methods . Stellar ages were determined based on kinematic indicators (such as the membership to young moving groups), age diagnostics (lithium abundance, rotation, and activity), and isochrone fitting. A thorough vetting for binarity was undertaken combining astrometric, spectroscopic, and imaging data. Results . A subsample of 333 stars, covering a large extent of stellar ages and masses, was constructed. Selection criteria, global features, as well as the properties of individual stars are reported and discussed.

Over the past decade, ALMA has uncovered a range of substructures within exoKuiper belts, pointing to a population of undetected planets. With JWST's sensitivity, we now have the opportunity to identify these planets thought to be responsible for the observed substructures in debris discs. We present Cycle 1 JWST/MIRI 11.4 μm coronagraphic observations of three exoKuiper belts that exhibit gaps in their radial structures: HD 92945, HD 107146, and HD 206893, to determine whether planets are responsible for carving these structures, as seen in our Solar System with the gas giants. We reduce the JWST/MIRI data using spaceKLIP, and introduce new routines to mitigate the Brighter-Fatter effect and persistence. We do not detect any planet candidates, and all detected objects in the field-of-view are consistent with background stars or galaxies. However, by combining JWST mass limits, archival observational constraints, and astrometric accelerations, we rule out a significant portion of planet parameter space, placing tight constraints on the planets possibly responsible for these gaps. To interpret these results, we explore multiple gap-carving scenarios in discs, either massless or with non-zero mass, including clearing by in-situ planet(s), as well as shaping by inner planets through mean-motion or secular apsidal resonances. Finally, we conclude that the planets causing the proper motion anomaly in these systems must reside within the inner 20 au.

Over the past decade, ALMA has uncovered a range of substructures within exoKuiper belts, pointing to a population of undetected planets. With James Webb Space Telescope (JWST)’s sensitivity, we now have the opportunity to identify these planets thought to be responsible for the observed substructures in debris discs. We present Cycle 1 JWST/MIRI $11.4~\mu$m coronagraphic observations of three exoKuiper belts that exhibit gaps in their radial structures: HD 92945, HD 107146, and HD 206893, to determine whether planets are responsible for carving these structures, as seen in our Solar system with the gas giants. We reduce the JWST/MIRI data using spaceklip, and introduce new routines to mitigate the Brighter-Fatter effect and persistence. We do not detect any planet candidates, and all detected objects in the field of view are consistent with background stars or galaxies. However, by combining JWST mass limits, archival observational constraints, and astrometric accelerations, we rule out a significant portion of planet parameter space, placing tight constraints on the planets possibly responsible for these gaps. To interpret these results, we explore multiple gap-carving scenarios in discs, either massless or with non-zero mass, including clearing by in situ planet(s), as well as shaping by inner planets through mean-motion or secular apsidal resonances. Finally, we conclude that the planets causing the proper-motion anomaly in these systems must reside within the inner 20 au.

Aims . This study aims to characterize debris disk targets observed with SPHERE across multiple programs, with the goal of identifying systematic trends in disk morphology, dust mass, and grain properties as a function of stellar parameters. By combining scattered-light imaging with photometric and parametric modeling, we seek to improve our understanding of the composition and evolution of circumstellar material in young debris systems and to place debris disks in the broader context of planetary system architectures. Methods . We analyzed a sample of 161 young main-sequence stars using archival SPHERE observations at optical and near-infrared (IR) wavelengths. Disk geometries were derived from ellipse fitting and model grids, while dust mass and properties were constrained by modified blackbody (MBB) and size distribution (SD) modeling of spectral energy distributions (SEDs). We also carried out dynamical modeling to assess whether the observed disk structures can be explained by the presence of unseen planets. Results . We resolve 51 debris disks, including four new detections where disks are resolved for the first time: HD 36968, BD-20 951, and the inner belts of HR 8799 and HD 36546. In addition, we find a second transiting giant planet in the HD 114082 system, with a radius of 1.29 ± 0.05 R _Jup and an orbital distance of ~1 au, providing an important new benchmark for planet–disk interaction studies. Beyond these new detections, we identify nine multi-belt systems, with outer-to-inner belt radius ratios of 1.5–2, and find close agreement between scattered-light and millimeter continuum belt radii with a mean ratio R _belt (near-IR)/ R _belt (mm) of 1.05 ± 0.04. Belt radii scale weakly with stellar luminosity ( R _belt ∝ L _⋆ ^0.11±0.05 ), but show steeper dependencies when separated by CO and CO ₂ freeze-out regimes, and also increase with age as R _belt ∝ t _age ^0.37±0.11 . Uniform image modeling yields vertical disk aspect ratios of 0.02–0.06, consistent with collisionally stirred belts, while gas-rich systems show unusually small values. Inner density slopes steepen with stellar luminosity, indicating more efficient dust removal around luminous stars. Disk fractional luminosities follow collisional decay trends, declining as t _age ^{−1.18±0.14} for A-type and t _age ^{−0.81±0.12} for F-type stars. SD modeling yields minimum grain sizes consistently above the blowout limit, typically >0.8 μm, with a mean SD index of q = 3.6, assuming astrosilicate composition. The inferred dust masses span 10 ⁻⁵ −1 M _⊕ from MBB modeling (and 0.01–1 M _⊕ from SD modeling for detected disks). These masses scale as R _belt ⁿ with n > 2 in belt radius and super-linearly with stellar mass, consistent with trends seen in protoplanetary disks (PPDs). Our detailed analysis of disk scattered-light non-detections indicates that they are mainly caused by low dust masses, unfavorable viewing geometries, or suboptimal observing conditions. SD modeling combined with Mie theory further shows that bulk albedos are consistently above 0.5 with little variation, making albedo differences an unlikely explanation. To explore this further, we introduced a new parametric approach based on scattered-light and polarized-light images, which provides independent estimates of dust albedo and maximum polarization fraction. We find a correlation between measured disk polarized flux and IR excess, with a slope shallower than that of optical total-intensity fluxes measured with HST/STIS. The offset of ~1 dex between total-intensity and polarized fluxes arises because polarized flux represents only a fraction of the total scattered light which depends on both grain properties and disk inclination. Finally, a comparison of planetary architectures shows that most benchmark systems resemble the Solar System, with multiple planets located inside wide Kuiper-belt analogues. Dynamical modeling further indicates that many observed gaps and inner edges can be explained by unseen planets below current detection thresholds, typically with Neptune- to sub-Jovian masses, underscoring the likely ubiquity of such planets in shaping debris disk morphologies.

High spatial resolution images of the volcanic moon Io at visible and near-infrared wavelengths were obtained by the SHARK-VIS and SHARK-NIR instruments on the Large Binocular Telescope on UT 2025 February 18 and 23. Large-scale changes on Io’s surface are identified in these data and provide vital context for infrared observations from other telescopes and spacecraft. SHARK-VIS imaged part of the plume deposit from a large eruption close to Io’s south pole at Illyrikon that was first observed by NASA’s Juno spacecraft in 2024 December, detecting significant deposit modification. Examples of other significant surface changes detected include at Seth, identifying a new pyroclastic deposit in addition to the new lava flows previously detected in Juno infrared observations; at Amirani, confirming that volcanic activity was now confined to the southern half of the Galileo-epoch lava flow field; new red sulphur-rich deposits at Mixcoatl; and changes in the plume deposits around Prometheus. Plume deposits at Prometheus and at other volcanoes show evidence of complex interplay between different plumes issuing from the same volcano. The combination of SHARK-VIS and Juno JunoCam data moves closer to near-global, near-contemporaneous, visible-wavelength coverage of Io. SHARK-VIS lives up to its promise of a new era of planetary imaging at visible wavelengths and filling the temporal coverage gap between Juno and the arrival of the Europa Clipper and JUICE spacecraft in the Jovian system in 2030 and 2031, respectively.

Context. High-angular-resolution observations in infrared and millimeter wavelengths of protoplanetary disks have revealed cavities, gaps, and spirals. One proposed mechanism to explain these structures is the dynamical perturbation caused by giant protoplanets. Aims. The purpose of this study is to detect and characterize potential protoplanets in the HD 135344B system. The star is located at ∼136 pc, and hosts a protoplanetary disk characterized by a 40 au cavity, multiple spiral arms detected in the optical/near-infrared, and a large-scale azimuthal asymmetry at millimeter wavelengths. Methods. We conducted deep high-contrast imaging observations using VLT/ERIS in the L′-band with the annular groove phase mask coronagraph (vortex coronagraph). Angular differential imaging with principal component analysis (ADI-PCA) was applied for the point spread function (PSF) subtraction to highlight the presence of point sources in the system. Results. We identified the previously detected S1, S2, S2a spiral arms and the “blob” features southward of the star. Besides this, we also identified a new point source at the base of the spiral arm (S2) embedded in the inner part of the disk at a separation of ∼ 0_.^″21, corresponding to a projected separation of ∼28 au, and a position angle of ∼87° (west of north). The point source has a contrast of ∼3 × 10⁻³. Our multiwavelength analysis implies a planetary mass of ≳2 M_Jup and large dust extinction (A_V ≳ 10 mag). Moreover, the L′-band flux of the candidate protoplanet and the upper limits at shorter wavelengths hint at the presence of a circumplanetary disk. Additionally, we report the detection of a previously unrecognized spiral arm located northwest of the star at a separation of ∼ 0_.^″77. No planets are detected in the outer disk with an upper limit of ∼600 K. Conclusions. These results suggest a physical link between the newly identified planet candidate and the observed disk substructures, supporting the scenario of a planet-driven origin for the cavity and spirals in the HD 135344B disk.

Context. During the Hunt for Observable Signatures of Terrestrial Systems (HOSTS) survey by the Large Binocular Telescope Interferometer (LBTI), an excess emission from the main-sequence star, θ Boo (F7V spectral type, 14.5 pc distance) was observed. This excess indicates the presence of exozodiacal dust near the star’s habitable zone (HZ). Previous observations with Spitzer and Herschel show no evidence of outer cold dust within their respective detection limits. Because exozodiacal dust is generally believed to originate from material located farther out in the system, its source around θ Boo remains unclear. Aims. We conducted additional nulling and high-contrast adaptive optics (AO) observations to spatially constrain the dust distribution, search for variability, and directly image potential companions in the system. This study presents the results of these observations and provides an interpretation of the inner system’s architecture. Methods. We observed the star using the LBTI’s N′-band nulling mode during three epochs in 2017, 2018, and 2023. For each epoch, we modeled and constrained the dust distribution using the standard LBTI nulling pipeline, assuming a vertically thin disk with a face-on inclination. We also performed high-contrast AO observations in the L′-band and H-band to constrain the presence of substellar companions around the star. Results. We find several solutions for the dust distribution for each epoch. However, the LBTI nulling observations are unable to discriminate between them. Using upper limits from previous observations, we constrain the representative size of the dust grains to approximately 3-5 μm. We also measured a tentative increase in dust brightness at the Earth-equivalent insolation distance between 2017 and 2023. This increase corresponds to the injection of 4 × 10⁻⁸−4 × 10⁻⁷ M_⊕ of new material into the disk. We consider several options to explain the origin of the observed dust and its variability, but no clear sources are identified from the current observations, partly because our high-contrast AO observations could only constrain the presence of companions only down to 11 M_Jup at 1.3″ separation.

Aims. We present high-contrast imaging observations of seven protoplanetary disks at 4 μm using the Enhanced Resolution Imager and Spectrograph (ERIS) on the Very Large Telescope. This study focuses on detecting scattered light from micron-sized dust particles and assessing the potential of the grating vector Apodizing Phase Plat (gvAPP) coronagraph for disk and planet characterization. Methods. Observations were performed in pupil-stabilized mode with the vAPP coronagraph. Data were reduced using reference differential imaging and angular differential imaging techniques, incorporating principal component analysis for point-source detection. Contrast curves and detection limits were computed for planetary companions and disk features. Results. The infrared disk signal was resolved in all systems, with first-time 4 μm detections around AS 209 and Elias 2-24, revealing mostly axisymmetric structures extending up to 60 au. Two gaps were detected in the radial profiles of TW Hya (22 au, 35 au) and AS 209 (50 au, 100 au). For Elias 2-24, scattered light emission matched ALMA observations of inner disk structures, marking their first mid-infrared detection. In the case of HD 100546, the vAPP uncovered flared disk structures and faint spiral arms consistent with previous observations. HD 163296 shows a bright inner dust ring, confirming disk asymmetries and features, but we did not detect any planet candidate within the achieved contrast limits. The disk around PDS 70 exhibits clear features, with faint structures detected within the cavity. The observations achieved contrasts enabling the detection of planets down to 800 K, but no companions were detected, implying either low-mass planets, cooler formation scenarios, or a large dust extinction of A_V ≳ 20 mag. Conclusions. The vAPP performed robustly for imaging structures in protoplanetary disks at 4 μm, providing critical insights into disk morphology and constraints on planet formation processes. No planetary-mass companions with temperatures >1000 K are present in our sample.