Ioannis Apergis

HIP 67522 is a one of the youngest multi-planetary systems discovered to date. The 17 Myr-old, Sun-like star is part of the Scorpius-Centarus OB association and is known to host two Saturn-sized planets in a near 2:1 mean motion resonance. We analysed photometric transits observed with the CHaracterising ExOPlanet Satellite (CHEOPS), the Transiting Exoplanets Survey Satellite (TESS), and multiple ground-based facilities to search for transit timing variations induced by planet-planet gravitational interactions, as well as transit depth variations, linked with the changing coverage of active regions on the stellar surface. We do not detect any transit timing variations for HIP 67522 b exceeding two minutes, contrary to previous results from the James Webb Space Telescope. In addition, we found that the observed transit depth of planet b changes strongly over time, with a >30% variation in amplitude. The high sensitivity and blue bandpass of the CHEOPS satellite also enabled us to identify multiple starspot crossings and measure their properties, including spot temperatures and sizes. We also measured the shear of the host star’s differential rotation by modelling the out-oftransit photometric variability and concluded that HIP 67522 exhibits a supersolar differential rotation. Based on internal structure models and planet formation simulations, we find that more than 20% of the mass of HIP 67522 b, at the system’s current age, is likely made of gaseous envelopes. Evolutionary simulations further indicate that both planets in the system will experience significant photoevaporation, evolving into either Earth size planets with completely stripped atmospheres or sub-Neptune-sized planets.

Source extraction is a fundamental task in astronomical data analysis, yet existing methods are often specialized to specific instruments, spectral bands, or imaging conditions, which limits their generalizability. In this work, we propose Extract Anything for Astronomy (EAA), a unified and perception-driven framework that adapts the Segment Anything Model (SAM) into a general-purpose astronomical source-extraction system. By introducing domain-aware input reprojection and full fine-tuning of the feature encoder, we systematically bridge the substantial domain gap between natural images and astronomical data. EAA integrates two complementary extraction paradigms, i.e., interactive and automatic extraction, enabling flexible usage across a broad range of spectral regimes and representative imaging conditions. Extensive experiments on CANDELS (approaching 80% completeness for sources with H < 27 AB) demonstrate improved deblending capability, faint source detection, and extraction robustness. More importantly, we validate the generalizability of EAA across a wide range of spectral regimes, including ultraviolet (GALEX, >95% completeness for sources with near-UV < 21), ground-based visible-light observations (>90% completeness for sources with Gaia-G < 12), radio (FIRST, >95% completeness for sources with FPEAK > 5), and millimeter-wave (Atacama Large Millimeter/submillimeter Array) data. Compared with SExtractor, Morpheus, and SAM, EAA provides the more comprehensive functionality and stronger deblending and perceptual segmentation capabilities, while its main limitation is lower faint-source detection sensitivity than SExtractor. These results show that perception-driven segmentation based on foundation models can serve as a powerful and universal paradigm for astronomical source extraction, providing a scalable infrastructure for next-generation sky surveys, space domain awareness, and cross-band scientific analysis.

The European Space Agency is set to launch PLAnetary Transits and Oscillations of stars (PLATO), the third medium-class mission of its Cosmic Vision programme, in early 2027. Using the transit method, PLATO is expected to detect thousands of exoplanets orbiting bright, nearby stars of spectral types F5–K7. Although the mission is primarily designed to enable mass measurements via radial velocities, its precise photometry and long observational baselines may also permit the detection of transit timing variations (TTVs), which can provide complementary dynamical constraints in multiplanet systems. One possible PLATO observing scenario involves a 2-yr-long observation of a northern field that may partially or fully overlap with the original Kepler field, creating an opportunity to revisit known multiplanet systems with a photometric baseline exceeding 20 yr. We simulate PLATO observations of 152 Kepler host stars containing at least one planet with previously detected TTVs, yielding a sample of 361 transiting planets. Our CCD-level simulations incorporate realistic stellar variability and employ both aperture and PSF (point spread function)-fitting photometry, accounting for each target’s real photometric contaminants. While the extended temporal baseline offers the potential for improved dynamical constraints in favourable cases, our simulations show that this potential is strongest for carefully selected systems, as PLATO’s smaller collecting area and larger pixel scale limit the achievable per-transit precision relative to Kepler. We identify a subset of systems most likely to benefit from complementary dynamical constraints through PLATO observations.

We identify two large-radius planets around the F-type star HD 114082 as the longest-period young transiting exoplanets known. From the first transit, detected by NASA’s Transiting Exoplanet Survey Satellite (TESS), and a second dip, spotted by the Next-Generation Transit Survey (NGTS), we predicted midtransit times for HD 114082 b (planet b). We pinpoint its orbit (period P _b = 225.5504 ± 0.0004 days) from a third transit captured with the ESA’s CHaracterising ExOplanet Satellite and the upgraded Antarctic Search for Transiting ExoPlanets telescope (ASTEP+), alongside orbit-discriminating observations. Another dimming partly covered by ASTEP+ completes the four-transit series. We support with dynamical evidence the planetary nature of a deeper transit detected with TESS and NGTS, identifying planet c. Additionally, we reexamine the debris disk, fitting its excess emission with two dust components. Fundamental stellar parameters are inferred from stellar evolution models, while a joint modeling of photometric and radial velocity time series yields the planetary parameters, with masses further constrained using an N-body code. For planet b, the semimajor axis a _b = 0.791 ± 0.008 au, eccentricity e _b ≈0, inclination i _b = 89 . ° 791 ±0.014, radius R _b = 1.046 ± 0.014 R _J , and 95% confidence upper limit on its mass M _95%,b = 1.6 M _J . For planet c, a _c = 0.99 − 0.04 + 0.03 au, e _c ≈0, i _c = 89 . ° 701 ±0.011, R _c = 1.36±0.03 R _J , and M _95%,c = 2.0 M _J (0.24 M _J if adding transit-timing-variation constraints). They seem to be moderate-to-low-mass giants in nearly resonant, coplanar, circular orbits that formed in situ, or beyond the snow line, and migrated inward, shaping the disk.

Observations have shown that planets similar to Neptune are rarely found orbiting Sun-like stars with periods up to ∼4 days. This defines the so-called Neptune desert region. The detection of each individual planet in this region therefore holds a high value by providing detailed insights into the formation and evolution of this population. We report the detection of TOI-333b, a Neptune-desert planet with a mass, radius, and bulk density of 20.1 ± 2.4 M _⊕ , 4.26 ± 0.11 R _⊕ , and 1.42 ± 0.21 g cm ⁻³ . The planet orbits an F7V star every 3.78 d, whose mass, radius, and effective temperature are of 1.2 ± 0.1 M _⊙ , 1.10 ± 0.03 R _⊙ , and 6241 ₋₆₂ ⁺⁷³ K, respectively. TOI-333bis likely younger than 1 Gyr, which is supported by the doublet Li line around 6707.856 Å and its comparison to Li abundances in open clusters with well-constrained ages. The planet is expected to host only a 8.5 _−8.3 ^+10.9 % gas-to-core mass ratio for an H/He envelope. On the other hand, models of irradiated ocean worlds predict a 20 ₋₁₀ ⁺¹¹ % H ₂ O mass fraction with a core fraction of 35 ₋₂₃ ⁺²⁰ %. We therefore expect that the internal composition of TOI-333bis dominated by a pure rocky composition with almost no H/He envelope, or a rocky world with almost equal mass fraction of water. Finally, TOI-333bis more massive and larger than 77% and 82% of its Neptune-desert counterparts, and its host ranks among the hottest known stars for Neptune-desert planets. This makes this system a unique laboratory for studying the evolution of these planets around hot stars.