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ALMA-IMF observed 15 massive protoclusters capturing multiple spectral lines and the continuum emission. Here, we focus on the massive protocluster G351.77 (~2500 M_⊙, estimated from single-dish continuum observations) located at 2 kpc. We trace the dense gas emission and kinematics with N₂H⁺(1–0) at ~4 kau resolution. We estimate an N₂H⁺relative abundance of ~(1.66 ± 0.46) × 10⁻¹⁰. We decompose the N₂H⁺emission into up to two velocity components, highlighting the kinematic complexity in the dense gas. By examining the position-velocity (PV) and position-position-velocity (PPV) diagrams on small scales, we observe clear inflow signatures (V-shapes) associated with 1.3 mm cores. The most prominent V-shape has a mass inflow rate of ~13.45 × 10⁻⁴M_⊙yr⁻¹and a short timescale of ~11.42 kyr. We also observe V-shapes without associated cores. This suggests both that cores or centers of accretion exist below the 1.3 mm detection limit, and that the V-shapes may be viable tracers of very early accretion and star formation on ~4 kau scales. The large-scale PV diagram shows that the protocluster is separated into two principal velocity structures separate by ~2 km s⁻¹. Combined with smaller-scale DCN and H₂CO emission in the center, we propose a scenario of larger-scale slow contraction with rotation in the center based on simple toy models. This scenario is consistent with previous lines of evidence, and leads to the new suggestion of outside-in evolution of the protocluster as it collapses. The gas depletion times implied by the V-shapes are short (~0.3 Myr), requiring either very fast cluster formation, and/or continuous mass feeding of the protocluster. The latter is possible via the Mother Filament that G351.77 is forming out of. The remarkable similarities in the properties of G351.77 and the recently published work in G353.41 indicate that many of the physical conditions inferred via the ALMA-IMF N₂H⁺observations may be generic to protoclusters. 

Context. Direct observations of exoplanet and brown dwarf companions with near-infrared interferometry, first enabled by the dualfield mode of VLTI/GRAVITY, provide unique measurements of the objects’ orbital motions and atmospheric compositions. Aims. Here we compile a homogeneous library of all exoplanet and brown dwarfK-band spectra observed by GRAVITY thus far. This ExoGRAVITY Spectral Library is made publicly available online. Methods. We re-reduced all the available GRAVITY dual-field high-contrast data in a uniform and highly automated way and, where companions were detected, extracted their ~2.0-2.4 μmK-band contrast spectra. We then derived stellar model atmospheres for all the employed flux references (either the host star or the swap calibrator), which we used to convert the companion contrast into companion flux spectra. Solely from the resulting GRAVITYK-band flux spectra, we extracted spectral types, spectral indices, and bulk physical properties for all the companions. Finally, and with the help of age constraints from the literature, we also derived isochronal masses for most of the companions using evolutionary models. Results. The resulting library containsR~ 500 GRAVITYK-band spectra of 39 substellar companions from late M to late T spectral types, including the entire L-T transition. Throughout this transition, a shift from CO-dominated late M- and L-type dwarfs to CH₄-dominated T-type dwarfs can be observed in theK-band. The GRAVITY spectra alone constrain the objects’ bolometric luminosity to typically within ±0.15 dex. The derived isochronal masses agree with dynamical masses from the literature where available, except for HD 4113 c for which we confirm its previously reported potential underluminosity. Conclusions. Medium-resolution spectroscopy of substellar companions with GRAVITY provides insight into the carbon chemistry and the cloudiness of these objects’ atmospheres. It also constrains these objects’ bolometric luminosities, which can yield measurements of their formation entropy if combined with dynamical masses, for instance from Gaia and GRAVITY astrometry. 

Context. A low-mass companion potentially in the brown dwarf mass regime was discovered on a ~12 yr orbit (~5.5 au) around HD 167665 using radial velocity (RV) monitoring. Joint RV–astrometry analyses confirmed that HD 167665B is a brown dwarf with precisions on the measured mass of ~4–9%. Brown dwarf companions with measured mass and luminosity are valuable for testing formation and evolutionary models. However, its atmospheric properties and luminosity are still unconstrained, preventing detailed tests of evolutionary models. Aims. We further characterize the HD 167665 system by measuring the luminosity and refining the mass of its companion and reassessing the stellar age. Methods. We present new high-contrast imaging data of the star and of its close-in environment from SPHERE and GRAVITY, which we combined with RV data from CORALIE and HIRES and astrometry from HIPPARCOSandGaia. Results. The analysis of the host star properties indicates an age of 6.20 ± 1.13 Gyr. GRAVITY reveals a point source near the position predicted from a joint fit of RV data and HIPPARCOS–Gaiaproper motion anomalies. Subsequent SPHERE imaging confirms the detection and reveals a faint point source of contrast of ∆H2= 10.95 ± 0.33 mag at a projected angular separation of ~180 mas. A joint fit of the high-contrast imaging, RV, and HIPPARCOSintermediate astrometric data together with theGaiaastrometric parameters constrains the mass of HD 167665B to ~1.2%, 60.3 ± 0.7M_J. The SPHERE colors and spectrum point to an early or mid-T brown dwarf of spectral type T4₋₂⁺¹. Fitting the SPHERE spectrophotometry and GRAVITY spectrum with synthetic spectra suggests an effective temperature of ~1000–1150 K, a surface gravity of ~5.0–5.4 dex, and a bolometric luminosity log(L/L_⊙)=−4.892_−0.028^+0.024dex. The mass, luminosity, and age of the companion can only be reproduced within 3σby the hybrid cloudy evolutionary models of Saumon & Marley (2008, ApJ, 689, 1327), whereas cloudless evolutionary models underpredict its luminosity. 

This work focuses on active galactic nuclei (AGNs) and on the relation between the sizes of the hot dust continuum and the broad-line region (BLR). We find that the continuum size measured using optical/near-infrared interferometry (OI) is roughly twice that measured by reverberation mapping (RM). Both OI and RM continuum sizes show a tight relation with the H β BLR size, with only an intrinsic scatter of 0.25 dex. The masses of supermassive black holes (BHs) can hence simply be derived from a dust size in combination with a broad line width and virial factor. Since the primary uncertainty of these BH masses comes from the virial factor, the accuracy of the continuum-based BH masses is close to those based on the RM measurement of the broad emission line. Moreover, the necessary continuum measurements can be obtained on a much shorter timescale than those required monitoring for RM, and they are also more time efficient than those needed to resolve the BLR with OI. The primary goal of this work is to demonstrate a measuring of the BH mass based on the dust-continuum size with our first calibration of the R BLR – R d relation. The current limitation and caveats are discussed in detail. Future GRAVITY observations are expected to improve the continuum-based method and have the potential of measuring BH masses for a large sample of AGNs in the low-redshift Universe. 

Here, we report the draft genome sequences of 10 marine Pseudoalteromonas bacteria that were isolated, assembled, and annotated by undergraduate students participating in a marine microbial genomics course. Genomic comparisons suggest that 7 of the 10 strains are novel isolates, providing a resource for future marine microbiology investigations. 

With four companions at separations from 16 to 71 au, HR 8799 is a unique target for direct imaging, presenting an opportunity for a comparative study of exoplanets with a shared formation history. Combining new VLTI/GRAVITY observations obtained within the ExoGRAVITY program with archival data, we performed a systematic atmospheric characterisation across all four planets. We explored different levels of model flexibility to understand the temperature structure, chemistry, and clouds of each planet using bothpetitRADTRANSatmospheric retrievals and fits to self-consistent radiative–convective equilibrium models. Using Bayesian model averaging to combine multiple retrievals (a total of 89 across all four planets), we find that the HR 8799 planets are highly enriched in metals, with [M/H] ≳1, and have stellar to superstellar atmospheric C/O ratios. The C/O ratio increases with increasing separation from 0.55_−0.10^+0.12for d to 0.78_−0.04^+0.03for b, with the exception of the innermost planet, which has a C/O ratio of 0.87 ± 0.03. Such high metallicities are unexpected for these massive planets, and challenge planet-formation models. By retrieving a quench pressure and using a disequilibrium chemistry model, we derive vertical mixing strengths compatible with predictions for high-metallicity, self-luminous atmospheres. Bayesian evidence comparisons strongly favour the presence of HCN in HR 8799 c and e, as well as CH₄in HR 8799 c, with detections at > 5σ confidence. All of the planets are cloudy, with no evidence of patchiness. The clouds of c, d, and e are best fit by silicate clouds lying above a deep iron cloud layer, while the clouds of the cooler HR 8799 b are more likely composed of Na₂S. With well-defined atmospheric properties, future exploration of this system is well positioned to unveil further details of these planets, extending our understanding of the composition, structure, and formation history of these siblings. 

Context. Dual-field interferometric observations with VLTI/GRAVITY sometimes require the use of a binary calibrator. This is a binary star whose individual components remain unresolved by the interferometer, with a separation between 400 and 2000 mas for observations with the Unit Telescopes (UTs), or 1200–3000 mas for the Auxiliary Telescopes (ATs). The separation vector also needs to be predictable to within 10 mas for a proper pointing of the instrument. Aims. No list of properly vetted calibrators was available so far for dual-field observations with VLTI/GRAVITY on the UTs. Our objective is to compile such a list and make it available to the community. Methods. We identified a list of candidates from the Washington Double Star (WDS) catalogue, all with appropriate separations and brightness, scattered over the southern sky. We observed them as part of a dedicated calibration programme, determined whether these objects were true binaries (excluding higher multiplicities resolved interferometrically, but unseen by imaging), and extracted measurements of the separation vectors. We combined these new measurements with those available in the WDS to determine updated orbital parameters for all our vetted calibrators. Results. We compiled a list of 13 vetted binary calibrators for observations with VLTI/GRAVITY on the UTs, and we provide orbital estimates and astrometric predictions for each of them. We show that our list guarantees that there are always two binary calibrators at least at an airmass < 2 in the sky over the Paranal observatory at any point in time. Conclusions. Any principal investigator wishing to use the dual-field mode of VLTI/GRAVITY with the UTs can now refer to this list to select an appropriate calibrator. We encourage the use of whereistheplanet to predict the astrometry of these calibrators, which seamlessly integrates with p2Gravity for VLTI/GRAVITY dual-field observing material preparation. 

Abstract Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)^1–3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase^4–6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8–12 billion years ago (redshifts 1–3)⁷. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-μas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 10⁸ solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 10¹¹ solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems. 

The angular size of the broad line region (BLR) of the nearby active galactic nucleus NGC 3783 has been spatially resolved by recent observations with VLTI/GRAVITY. A reverberation mapping (RM) campaign has also recently obtained high quality light curves and measured the linear size of the BLR in a way that is complementary to the GRAVITY measurement. The size and kinematics of the BLR can be better constrained by a joint analysis that combines both GRAVITY and RM data. This, in turn, allows us to obtain the mass of the supermassive black hole in NGC 3783 with an accuracy that is about a factor of two better than that inferred from GRAVITY data alone. We derive M BH = 2.54 −0.72 +0.90 × 10 7 M ⊙ . Finally, and perhaps most notably, we are able to measure a geometric distance to NGC 3783 of 39.9 −11.9 +14.5 Mpc. We are able to test the robustness of the BLR-based geometric distance with measurements based on the Tully–Fisher relation and other indirect methods. We find the geometric distance is consistent with other methods within their scatter. We explore the potential of BLR-based geometric distances to directly constrain the Hubble constant, H 0 , and identify differential phase uncertainties as the current dominant limitation to the H 0 measurement precision for individual sources.