Emilio Molinari

Context . Observing the earliest stages of high-mass star formation in the mid-infrared (mid-IR) is challenging because the extinction is high and the resolution limited. Millimeter vibrationally and torsionally excited transitions of several molecules have been proposed as indirect probes of local mid-IR radiation fields around young stellar objects (YSOs). Aims . We investigate the excitation and spatial distribution of torsionally excited methanol (CH ₃ OH) in 12 high-mass star-forming clumps in different evolutionary stages, assessing their potential as tracers of the mid-IR luminosity of embedded protostars. Methods . We analyzed rotational transitions of methanol within the same torsionally excited states v _t ≥1 in the Atacama Large Millimeter/submillimeter Array (ALMA) 890 µm observations and compared them with Spitzer 24 µm data by plotting line luminosities normalized by methanol abundance against mid-IR luminosities. Results . The torsionally excited methanol emission is generally compact and systematically coincident with ALMA dust continuum peaks and 24 µm emission, even in faint sources. The only clump without an IR counterpart also shows no v _t ≥1 emission, supporting radiative pumping as the dominant excitation mechanism. We found a promising power-law trend between v _t ≥1 methanol lines and 24 µm luminosities, largely independent of the methanol abundance. Conclusions . CH ₃ OH v _t ≥1 transitions appear to be promising tracers of local mid-IR radiation fields of embedded protostars, providing core-scale information even in highly extincted regions. As a pilot study, our results suggest that extending our study to a larger statistical sample is crucial for testing and improving this method.

Multi-planetary systems provide key constraints on planet formation and evolution, as their architecture encodes the dynamical history of planets formed within a common protoplanetary disc. However, the current population remains strongly biased towards compact, short-period systems, and only a limited number of such systems with measured masses and radii are known. HIP 41378 is an exceptional system hosting five transiting planets with orbital periods of up to 1.5 years, including an ultra-low-density planet, HIP 41378 f. The outer transiting planets d and e remained poorly constrained with unknown periods and masses, leaving the system architecture only partially characterised. We present long-term monitoring of this target with high-precision radial-velocity (RV) instruments (HARPS, HARPS-N, HIRES, and ESPRESSO) and space-based photometry spanning 2015–2024. We detected RV signals for all the planets, confirming their orbital periods and constraining their masses. In particular, the RV data strongly favour an orbital period of P _d = 278 days for planet d and refine the orbital period of planet e to P _e = 393 ₋₅ ⁺³ days. We measured a new mass of M _f = 25 ± 5 M _⊕ for HIP 41378 f, confirming its super-puff nature with a bulk density of ρ _f = 0.166 _−0.036 ^+0.033 g cm ⁻³ . We also confirm the planetary nature of HIP 41378 g, a non-transiting planet with a 63-day period, and determine its minimum mass. In addition, the RVs reveal a long-period signal, with P = 2602 ₋₄₃₃ ⁺⁴⁶⁸ days, which we attribute to the candidate planet HIP 41378 h, although a stellar magnetic cycle cannot be excluded. Finally, we investigated the system’s dynamical architecture and resonant structure, assessed its completeness by constraining additional undetected planets, and looked into the implications for the origin and internal structure of the remarkable planet HIP 41378 f.

Context. The HARPS-N solar telescope has been observing the Sun every possible day since the summer of 2015. We have recently released 10 years of these data, which are available online. Aims. The goal of this paper is to present the different optimisations made to the ESPRESSO data reduction software used to extract the published HARPS-N solar spectra, describe the data curation, and perform some analyses that demonstrate the extreme radial velocity (RV) precision of those data. Methods. By analysing all of the HARPS-N wavelength solutions over 13 years, we brought to light instrumental systematics at the 1 m s ⁻¹ level. We mitigated those systematics by curating the thorium line list used to derive the wavelength solution and applying a correction to the drift of thorium lines induced by the aging of thorium-argon hollow cathode lamps. After optimisation, we demonstrated a peak-to-peak precision on the HARPS-N wavelength solution better than 0.75 m s ⁻¹ over 13 years. We then carefully curated the decade of HARPS-N re-reduced solar observations by rejecting 30% of the data affected either by clouds, bad atmospheric conditions, or well-understood instrumental systematics. Finally, we corrected the curated data for spurious sub-meter-per-second RV effects caused by erroneous instrumental drift measurements and by changes in the spectral blaze function over time. Results. After curation and correction, a total of 109,466 HARPS-N solar spectra and respective RVs over a decade were made available. The median photon-noise precision of the RV data is 0.28 m s ⁻¹ , and on daily timescales, the median RV rms is 0.49 m s ⁻¹ , which is similar to the level imposed by stellar granulation signals. On 10 year timescales, the large RV rms of 2.95 m s ⁻¹ results from the RV signature of the Sun’s magnetic cycle. Through modelling of this long-term effect using the Bremen composite magnesium II activity index, we demonstrate a long-term RV precision of 0.41 m s ⁻¹ . We also analysed contemporaneous HARPS-N and NEID solar RVs and found the data from both instruments to be of similar quality and precision. However, an analysis of the RV difference between these two RV datasets over the three available years gave a surprisingly large RV rms of 1.3 m s ⁻¹ . This variation is dominated by an unexplained trend that could be caused by a different sensitivity to stellar activity of the two datasets. Once this trend was modelled, the overall RV rms for three years reached 0.79 m s ⁻¹ , and the RV rms during the low-activity phase decreased to 0.6 m s ⁻¹ , compatible with what is expected from supergranulation. Conclusions. This decade of high-cadence HARPS-N solar observations with short- and long-term precision below one m s ⁻¹ represents a crucial dataset in the pursuit of further understanding the stellar activity signals in solar-type stars and advancing other science cases requiring such extreme precision.

Observations over the past few decades have found that planets are common around nearby stars in our Galaxy, but little is known about planets that formed outside the Milky Way. We describe the design and early implementation of a survey to test whether planets also exist orbiting the remnant stars of ancient dwarf galaxies that merged with the Milky Way, and if so, how they differ from their Milky Way counterparts. VOYAGERS ( Views Of Yore —Ancient Gaia-enceladus Exoplanet Revealing Survey ) is a radial velocity (RV) search using precision spectrographs to discover exoplanets orbiting very low metallicity (−2.8 < [Fe/H] ≤ −0.8) stars born in the dwarf galaxy Enceladus, which merged with the Milky Way galaxy about 10 Gyr ago. A sample of 22 candidates have been screened from a catalog of Gaia–Enceladus–Sausage (GES) members using a combination of stellar properties and reconnaissance observations from the TRES spectrograph. Precision RV measurements have been initiated using the NEID, HARPS-N, and CARMENES spectrographs. We plan to focus most upcoming observations on 10 main sequence targets. Data collection is well underway, with 778 observations on 22 candidates (385 of which are on 10 focus targets), but far from complete. This survey is designed to be sensitive to sub-Neptune mass planets with periods up to hundreds of days. We note that the RV analysis gives mass multiplied by sin ( inclination ) or the minimum mass for exoplanets. The expected survey yield is three planets, assuming that occurrence rates are similar to those in the Milky Way and taking into account the degeneracy with inclination in our yield models. Our survey is designed to detect at least one exoplanet if occurrence rates are similar to known Milky Way exoplanets or, if no exoplanets are discovered, to rule out a Milky Way-like planet population in GES with 95% confidence level.

The next generation of Extremely Large Telescopes (ELTs), with their wide apertures and advanced multi-conjugate adaptive optics (MCAO) systems, will provide unprecedented sharp and deep observations, even surpassing the capabilities of the James Webb Space Telescope. SHARP, a near-infrared (0.95 to 2.45 μm) spectrograph, is designed to optimally exploit the collecting area and angular resolution of these forthcoming ELTs and specifically optimized for the MCAO unit MORFEO at the ELT. SHARP includes two main units: NEXUS, a multi-object spectrograph, and VESPER, a multi-integral field unit. We outline the opto-mechanical design of SHARP based on the scientific requirements of the project. The optical design is engineered to meet project specifications, featuring a compact mechanical structure that minimizes the required cryogenic power while ensuring ease of access for maintenance and straightforward assembly procedures.

Context. V1298 Tau is a very young and magnetically active K1V star that hosts a benchmark multi-planetary system to study planet formation and evolutionary history at the earliest stages. Thanks to the high interest, it has been the target of a multi-wavelength follow-up. Aims. We selected V1298 Tau for a first targeted follow-up at radio frequencies with the Karl G. Jansky Very Large Telescope (JVLA), the upgraded Giant Metrewave Radio Telescope (uGMRT), and the Sardinia Radio Telescope (SRT) to search for emission in the overall frequency range 0.55–7.2 GHz. Detecting radio emission from such a very active star is key to characterising its magnetosphere, allowing us in principle to probe the strength of the coronal magnetic field and plasma density. Methods. Observations were carried out between October 2023 and September 2024: three epochs (total of ∼180 min on-source) with uGMRT band-4 (0.55–0.75 GHz), 12 epochs (total of ∼427 min on-source) with the JVLA using L (1–2 GHz) and C (4.5–6.5 GHz) bands, and three epochs (total of ∼56 min on-source) with SRT using C-high band (6–7.2 GHz). Results. We report the first detection of radio emission from V1298 Tau at different epochs using the JVLA. The emission has maximum peak flux densities of 91±10 and 177±6 µJy/beam in the L- and C-band, respectively. From a comparison with contemporary optical photometry, we found that the detected emission with the highest fluxes are located around a phase of minimum of the photospheric light curve. Although the uGMRT and SRT observations could not detect the source, we measured 3σ flux density upper limits in the range ∼41–56 µJy/beam using uGMRT, while with SRT we reached upper limits down to 13 mJy. The lack of a significant fraction of circular polarisation indicates that the observed flux is not due to electron cyclotron maser emission from star-planet interaction, and it is likely produced by gyrosynchroton and/or cyclotron emission from the corona triggered by stellar magnetic activity, although we cannot exclude thermal emission, due to a lack of constraints on the brightness temperature.

Context. HAT-P-67 b is one of the lowest-density gas giants known to date, making it an excellent target for atmospheric characterisation through the transmission spectroscopy technique. Aims. In the framework of the GAPS large programme, we collected four transit events of HAT-P-67 b with the aim of studying the exoplanet atmosphere and deriving the orbital projected obliquity. Methods. We exploited the high-precision GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo (TNG) along with additional archival TESS photometry to explore the activity level of the host star. We performed transmission spec-troscopy, both in the visible (VIS) and in the near-infrared (NIR) wavelength range, and we analysed the Rossiter–McLaughlin (RML) effect when fitting both the radial velocities and the Doppler shadow. Based on the TESS photometry, we redetermined the transit parameters of HAT-P-67 b. Results. By modelling the RML effect, we derived a sky-projected obliquity of (2.2 ± 0.4)°, indicating an aligned planetary orbit. The chromospheric activity index log R′_HK, the CCF profile, and the variability in the transmission spectrum of the Hα line suggest that the host star shows signatures of stellar activity and/or pulsation. We found no evidence of atomic or molecular species in the optical transmission spectra, with the exception of pseudo-signals corresponding to Cr I, Fe I, Ha, Na I, and Ti I. In the NIR range, we found an absorption signal of the He I triplet of 5.56_−0.30^+0.29% (19.0σ), corresponding to an effective planetary radius of ~3 R_p (where R_p ~ 2 R_J), which extends beyond the planet’s Roche lobe radius. Conclusions. Owing to the stellar variability and the high uncertainty of the model, we could not confirm the planetary origin of the signals found in the optical transmission spectrum. On the other hand, we were able to confirm previous detections of the infrared He I triplet, providing a 19.0σ detection. Our finding indicates that the planet’s atmosphere is evaporating.

Context. The atmospheric characterisation of hot and warm Neptune-size exoplanets is challenging mainly due to their relatively small radius and atmospheric scale height, which reduce the amplitude of atmospheric spectral features. The warm-Neptune HAT-P-11 b is a remarkable target for atmospheric characterisation because of the large brightness of its host star (V = 9.46 mag; H = 7.13 mag). Aims. The aims of this work are to review the main physical and architectural properties of the HAT-P-11 planetary system, and to probe the presence of eight molecular species in the atmosphere of HAT-P-11 b through near-infrared (NIR) high-resolution transmission spectroscopy. Methods. We reviewed the physical and architectural properties of the HAT-P-11 planetary system by analysing transits and occultations of HAT-P-11 b from the Kepler data set as well as HIRES at Keck archival radial-velocity data. We modelled the latter with Gaussian-process regression and a combined quasi-periodic and squared-exponential kernel to account for stellar variations on both (short-term) rotation and (long-term) activity-cycle timescales. In order to probe the atmospheric composition of HAT-P-11 b, we observed four transits of this target with the NIR GIANO-B at TNG spectrograph and cross-correlated the data with template atmospheric transmission spectra. Results. We find that the long-period radial-velocity signal previously attributed to the HAT-P-11 c planet (P ~ 9.3 yr; M_p sin i ~ 1.6 M_J; e ~ 0.6) is more likely due to the stellar magnetic activity cycle. Nonetheless, the HIPPARCOS-Gaia difference in the proper-motion anomaly suggests that an outer-bound companion might still exist. For HAT-P-11 b, we measure a radius of R_p = 0.4466 ± 0.0059 R_J, a mass of M_p = 0.0787 ± 0.0048 M_J, a bulk density of ρ_p = 1.172 ± 0.085 g cm⁻³, and an orbital eccentricity of e = 0.2577_−0.0025^+0.0033. These values are compatible with those from the literature. Probing its atmosphere, we detect the presence of two molecular species, H₂O and NH₃, with a S/N of 5.1 and 5.3, and a significance of 3.4 σ and 5.0 σ, respectively. We also tentatively detect the presence of CO₂ and CH₄, with a S/N of 3.0 and 4.8, and a significance of 3.2 σ and 2.6 σ, respectively. Conclusions. We revisit the HAT-P-11 planetary system, confirm the presence of H₂O, and report the detection of NH₃ in the atmosphere of HAT-P-11 b, also finding hints for the presence of CO₂ and CH₄ that need to be confirmed by further observations.