Eva Villaver

Context . The gas giant–planet metallicity correlation plays a fundamental role in our understanding of planet formation. However, that correlation is mostly derived from observations of solar-type stars. Aims . We aim to test whether the correlation between the metallicity and chemical abundances of the star and the presence of giant planets for solar-type stars still holds for early-type (spectral types A and early F) stars. Methods . We determined the metallicity and individual abundances of a large sample of A and early-F stars in a homogeneous way, with and without known planetary companions; in this paper, we discuss their abundance distribution and trends. Our methodology is based on the analysis of high-resolution échelle spectra. It includes the calculation of the fundamental stellar parameters by fitting the profiles of the Balmer lines, as well as individual abundances of different elements such as C, O, Mg, Si, Ca, Ti, Fe, Ni, and Ba via a multi-parameter fitting procedure of selected spectral regions. Results . We find that stars with planets generally exhibit higher abundances of both iron-peak and volatile elements compared to stars without known planets, although in most cases this tendency is not statistically significant. The C/O ratio remains similar between both samples, while the Mg/Si ratio is shifted towards higher values in the general planet host sample. When the sample is limited to fully radiative stars (spectral type earlier than F5), the statistical significance of carbon overabundances vanishes. In contrast, elements such as O and Ni remain significantly overabundant. The C/O and Mg/Si ratios in this radiative sub-sample are statistically indistinguishable from that of the comparison sample. Conclusions . The persistent overabundance of O and Ni, combined with C/O and Mg/Si ratios similar to those of stars without planets in fully radiative hosts, points to the ongoing surface pollution by volatile-poor, silicate-rich rocky debris, rather than the accretion of gas giants. These findings might position early-type main-sequence stars as a crucial dynamical missing link in the chemical life cycle of planetary systems; such a link would bridge the initial dust-trapping phase in pre-main-sequence transition discs, the dilution of this superficial pollution during the fully convective red giant phase, and the eventual dynamically driven accretion of asteroid material observed in polluted white dwarfs.

Context. The Pennsylvania-Toruń Planet Search, which operates on a sample of ∼1000 northern-hemisphere stars, has been underway since 2004. Stars with radial velocity (RV) amplitudes exceeding 2 km s ⁻¹ represent a backup subprogram sample dedicated to monitoring binary stars with multiple instruments. Aims. We used almost 21 years of combined RV measurements to search for Doppler signals consistent with stellar or brown dwarf companions and to produce a catalog of both known and previously unpublished binary stars in our planet-search sample. Methods. We analyzed the combined RV measurements, searching for stellar companions and obtaining orbital solutions for both known and new binary systems. We also searched for periods in available long-term photometric monitoring data from All Sky Automated Survey (ASAS), and applied Gaia astrometric data whenever available. Results. We report the results of long-term RV monitoring of 16 systems: new detections of low-mass companions to 11 stars and updated orbital elements based on combined sets of our new and literature data for five systems. For two objects (TYC 3318-00789-1 and TYC 3318-01538-1), we find evidence of activity or the influence of another unseen companion, possibly due to line-profile variations or unresolved spectral contamination. We present true masses for three systems in our sample: TYC 1931-1040-1, TYC 3451-1449-1, and TYC 3667-1636-1. We obtained these masses using Gaia DR3 non-single star data.

Context. Understanding the large-scale dynamics of molecular clouds (MCs) is crucial to constraining the processes that govern star formation and the structure and evolution of the Galaxy. While gas tracers have traditionally been used to map MC kinematics, stellar tracers such as young stellar objects (YSOs) and open clusters (OCs) provide a complementary approach that enables direct comparisons between the stellar and gaseous components. Aims. We aim to compare the kinematics of young (≤30 Myr) OCs with YSOs in the same star-forming region, the latter being assumed to trace the motions of the parent cloud gas. Subsequently, we intend to reconstruct the three-dimensional (3D) motions of the main MC complexes within 2.5 kpc of the Sun using both YSOs and young OCs as tracers. Methods. Using Gaia Data Release 3 (DR3) astrometry and complementary spectroscopic surveys providing radial velocities (RVs), we compiled a unified sample of24 146 young stars, comprising YSOs and OC members. We applied robust clustering in proper-motion space to identify co-moving YSOs and derived cloud-averaged motions via Monte Carlo sampling. These motions were compared with the kinematics inferred from OCs younger than 30 Myr. Finally, we performed orbital integrations in a realistic Galactic potential to trace the past evolution of the clouds and to quantify their expansion and rotation. Results. We derive homogeneous 3D kinematics for 15 star-forming regions within 2.5 kpc. YSOs and OCs exhibit strongly consistent kinematics within each cloud, with a median spatial velocity offset of ≲2 km s ⁻¹ , allowing us to combine them into a unified tracer sample. The resulting bulk cloud motions show a median peculiar velocity of ≃9 km s ⁻¹ with respect to the Galactic rotation. We used our catalogue to trace back the Solar System’s voyage through the Orion cloud and the common origin of Lupus, Ophiuchus, and Corona Australis in the Sco-Cen region. Internally, we detected significant expansion in Orion and Ophiuchus (at a 5 σ level) and coherent rotation in at least six complexes, likely reflecting local processes such as stellar feedback and angular-momentum redistribution. Conclusions. Young OCs and YSOs exhibit broadly consistent kinematics, and therefore OCs can also be used to trace the bulk motion of the star-forming regions.

We present new CHEOPS transit observations of AU Mic b and AU Mic c obtained between June and September 2024, extending the baseline of transit-timing measurements of this young planetary system. For AU Mic b, the timing signal is well established, with a semi-amplitude (10 ± 3 min) and a characteristic modulation timescale (1168 ± 20 d) consistent with previous determinations. By contrast, the new CHEOPS data show that the large transit-timing deviation of AU Mic c reported previously was not sustained. After the steadily increasing timing trend observed in 2022 and 2023, the 2024 timings returned closer to the zero point of the observed-minus-calculated diagram, indicating a reversal of the previously reported behavior. For AU Mic c, both the transit-timing semi-amplitude (46 ± 26 min) and the characteristic modulation timescale (2150 ± 110 d) remain tentative. These results highlight the importance of continued long-term monitoring of the AU Mic system.

Scientific publishing is undergoing major change, driven by a shift toward open access (OA), the rise of artificial intelligence (AI), and growing demands for transparency, reproducibility, and equity. At the same time, rapid growth in article output strains editors and reviewers and means that metrics and speed can eclipse quality and rigor. To better understand how the community is responding, Astronomy & Astrophysics (A&A) commissioned the A&A Survey on Trends and Challenges in Scientific Publishing, which documents community opinion on journal choice, peer review, OA, research evaluation, and the role of AI, with the goal of informing future editorial policies and the wider conversation on sustainable, ethical, and equitable scientific communication. Distributed online in May 2025 to 28 787 A&A authors and co-authors, the 13-question survey drew 2944 responses from 69 countries by its closing date. Quantitative answers were analyzed through frequency distributions, and roughly 3000 free-text comments were grouped into recurring themes. The responses were clear. Journal quality and reputation are the most decisive factors in deciding where to publish, followed by cost. The principal worry about peer review is reviewer expertise and fairness rather than speed. Citation counts are still an important consideration, but many respondents want broader, more qualitative measures of impact. The majority of them prefer public or institutional funding for OA, and views on AI are polarized, with widespread acceptance of administrative and language assistance but firm opposition to autonomous decision-making or content generation. Integrity, credibility, and fairness are common themes in every section of the responses. Overall, the survey portrays an engaged community that values quality over speed, fairness over profit, and human oversight over automation, providing A&A with clear insight into community preference and a solid framework for shaping future policies on OA, peer review, and the responsible integration of AI.

Context . Following the 2022 alert of a TESS object of interest transiting TOI-5624 (a G7 V star ∼ 100 pc away), a CHEOPS campaign in 2023 detected four planetary signals at P _b ≈ 3.4, P _c ≈ 7.9, P _d ≈ 13.7, and P _e ≈ 21.5 days. These signals were later confirmed by additional TESS and CHEOPS photometry in 2024-2025. Aims . By using TESS and CHEOPS photometry, along with HARPS-N and SOPHIE high-resolution spectra, we determined the planet properties and performed a dynamical analysis of the system. Methods . After analysing the photometric data, we extracted and modelled the radial velocity (RV) time series using two independent methodologies, both within a Markov chain Monte Carlo framework. We further integrated the N -body equations of motion, while simultaneously fitting the transit times and the detrended RVs, to dynamically characterise the system. Results . We present the discovery of four transiting sub-Neptunes with radii of R _b = 2.314 ± 0.035 R _⊕ , R _c = 2.474 ± 0.042 R _⊕ , R _d = 3.584 _−0.050 ^+0.051 R _⊕ , and R _e = 3.247 _−0.043 ^+0.042 R _⊕ , along with masses of M _b = 9.4 ± 1.4 M _⊕ , M _c = 4.8 ± 1.9 M _⊕ , Md = 4.9 ± 2.2 M _⊕ , and M _e = 8.9 _−3.0 ^+2.9 M _⊕ . Our photometric analysis revealed that the outermost transiting planet TOI-5624e shows significant transit-timing variations (TTVs). Indeed, we found a robust Keplerian signal in the RV time series close to the 2:1 period commensurability with TOI-5624 e, which explains the TTV pattern exhibited by TOI-5624 e according to our dynamical analysis. We labelled this non-transiting planet as TOI-5624 f and determined its minimum mass to be M _f sin i _f = 13.0 ± 3.7 M _⊕ . Conclusions . Among the known systems hosting more than four planets, the remarkable precision with which the radii have been measured (3σ) of the mass for at least three planets has previously been reached only for TRAPPIST-1. Additional photometric observations will enable a better sample of the TTV modulation and a more robust dynamical determination of the masses.

Context. Interior models predict that stellar envelopes change from convective to radiative during the pre-main-sequence (pre-MS) evolution of intermediate-mass stars. Although the amount of surface lithium (Li) is a direct probe of mixing in stellar interiors, analyses focused on this type of source are practically absent. Aims. We contribute to our understanding of the evolution of young intermediate-mass stars by providing a comprehensive analysis of their Li content. Methods. A sample of 71 intermediate-mass T Tauri (IMTT) and Herbig stars within the mass range 1.5–3.5 M _⊙ was carefully selected for the analysis. Metallicities, rotational velocities, and accretion rates were obtained from spectra. The curves of growth for stars hotter than 8000 K were built to infer the Li abundances, which were interpreted considering standard models of stellar interiors and non-standard processes affecting Li depletion. Results. Li is generally less strongly depleted in intermediate-mass stars than in their lower-mass counterparts, as expected from standard evolution models. However, Li abundances significantly below the cosmic value are observed in 25–30% of intermediate-mass stars. It is also unexpected that the results show no significant difference between the 1.5–2.5 M _⊙ and 2.5–3.5 M _⊙ subsamples. Evidence is provided showing that disk-locking works in young intermediate-mass stars. This constitutes independent support for the hypothesis that magnetospheric accretion scenario operates in these sources. We found that disk-locking is effective for a timescale that is about twice shorter than for lower-mass stars, before magnetospheres reduce their sizes during the transition from the IMTT to the Herbig regime. This contraction of the magnetosphere can explain the increase in rotation by a factor of about 3 and in accretion by a factor of about 4 that is observed during this transition. We propose a complex scenario linking rotation, accretion, and the surface Li abundance. Finally, we tentatively suggest that the known relation between the presence of planets and Li depletion might also be present in intermediate-mass MS stars and might originate in the pre-MS. Conclusions. We provide the most complete Li analysis and database focused on IMTT and Herbig stars to date. However, we emphasize the need of additional observations and non-standard models such as those available for their lower-mass analogs.

3I/ATLAS is the third interstellar object discovered to date, following 1I/‘Oumuamua and 2I/Borisov. Its unusually high excess velocity and active cometary nature make it a key probe of the Galactic population of icy planetesimals. Understanding its origin requires its past trajectory through the Galaxy to be traced and the possible role of stellar encounters to be assessed, both as a potential origin and a perturber to its orbit. We integrated the orbit of 3I/ATLAS backward in time for 10 Myr, together with a sample of Gaia DR3 stars with high-quality astrometry and radial velocities, to identify close passages within 2 pc. We identify 93 nominal encounters, 62 of which are significant at the 2 σ level. However, none of these encounters produced any meaningful perturbation. The strongest perturber Gaia DR3 6863591389529611264 at 0.30 pc and with a relative velocity of 35 km s ⁻¹ , imparted only a velocity change of ∣Δ v ∣ ≃ 5 × 10 ⁻⁴ km s ⁻¹ to the orbit of 3I/ATLAS. Our results indicate that no stellar flybys within the past 10 Myr and 500 pc contained in Gaia DR3 can account for the present trajectory of 3I/ATLAS or be associated with its origin. We further show that 3I/ATLAS is kinematically consistent with a thin-disk population, despite its large peculiar velocity.

We present the characterisation of the TOI-6041 system, a bright ( V = 9.84 ± 0.03) G7-type star hosting at least two planets. The inner planet, TOI-6041 b, is a warm Neptune with a radius of 4.55 _−0.17 ^+0.18 R _⊕ , initially identified as a single-transit event in TESS photometry. Subsequent observations with TESS and CHEOPS revealed additional transits, enabling the determination of its 26.04945 _−0.00034 ^+0.00033 orbital period and the detection of significant transit-timing variations (TTVs), exhibiting a peak-to-peak amplitude of about 1 hour. Radial-velocity (RV) measurements obtained with the APF spectrographs allowed us to place a 3 σ upper mass limit of 28.9 M _⊕ on TOI-6041 b. In addition, the RV data reveal a second companion, TOI-6041 c, on an 88 d orbit, with a minimum mass of 0.25 M _Jup . A preliminary TTV analysis suggested that the observed variations could be caused by gravitational perturbations from planet c; however, reproducing the observed amplitudes requires a relatively high eccentricity of about 0.3 for that planet. Our dynamical stability analysis indicates that such a configuration is dynamically viable and places a 1 σ upper limit on the mass of TOI-6041 c at 0.8 M _Jup . An alternative is the presence of a third, low-mass planet located between planets b and c, or on an inner orbit relative to planet b – particularly near a mean-motion resonance with planet b – which could account for the observed variations. These findings remain tentative, and further RV and photometric observations are essential in to better constrain the mass of planet b and to refine the TTV modeling, thereby improving our understanding of the system’s dynamical architecture.