Sylvie Cabrit

We present 0 . ″ 1 (∼50 au) resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the HH 46/47 molecular outflow and its envelope–disk system. The 1.3 mm continuum emission reveals a compact central source surrounded by a circumbinary disk with substructures. The companion, identified in optical and infrared observations, is not detected in the millimeter continuum but coincides with a local intensity minimum. Two spur-like features extending from the primary source toward the companion are identified and are likely induced by gravitational perturbations from the companion. The envelope–disk system is traced by C ¹⁸ O, SO, H ₂ CO, and CH ₃ OH. C ¹⁸ O primarily traces the extended envelope, while SO probes the inner envelope, and H ₂ CO and CH ₃ OH trace compact, faster-rotating structures near the centrifugal barrier. The observations are well reproduced by a rotating–infalling envelope transitioning to an inner disk at a radius of ∼30 au around a 0.3 M _⊙ protostar. The ¹² CO emission, together with JWST NIRCam images, reveals multiple shell structures in the outflow. Using C ¹⁸ O and ¹³ CO to correct for optical depth, we derive the spatial distributions of outflow mass, momentum, and kinetic energy, as well as their corresponding rates. A model-independent analysis of a well-defined redshifted shell yields its three-dimensional velocity field, showing that the shell expands radially rather than flowing along its surface. Although a transverse velocity gradient is detected, interpreting it as rotation implies an unphysically large magnetic lever arm, disfavoring a direct disk-wind origin. Instead, the shell kinematics support an entrainment scenario.

The evolution and dispersal of protoplanetary disks—governed by accretion, magnetically launched jets and winds, and photoevaporative winds—fundamentally shape planetary systems. Determining how these mass-loss processes coevolve is crucial for constraining planet formation pathways. We analyze archival James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) integral field unit data of 72 inclined ( i > 40°), mostly Class II disks to identify and characterize spatially resolved jets and winds, focusing on [Ne II ] and H ₂ lines. Extended emission in H ₂ S(1), S(3), S(5), S(7), and/or [Ne II ] is detected toward 66 disks, revealing diverse morphologies. We develop a framework to identify conical H ₂ winds and high-velocity [Ne II ] jets perpendicular to the disk, detecting them toward 46 and 40 disks, respectively. All sources with [Ne II ] jets exhibit a corresponding wind traced in either H ₂ (85%) or [O I ], establishing a connection between jets and winds. The detection fractions of [Ne II ] jets and H ₂ winds correlate positively with mass accretion rate, with no dependence on disk inclination or stellar mass. Conversely, marginally resolved low-velocity [Ne II ] winds are found preferentially toward lower accretors. Among sources with H ₂ winds, detection of hotter winds traced by S(7) and S(5) declines more rapidly with decreasing accretion rate than that of the colder S(1) component. Comparison with high-resolution [O I ] 6300Å spectroscopy reveals [O I ] low-velocity components and extended H ₂ wind detections preferentially toward moderate-to-high accretors ( ≳ 1 0 − 8.5 M ̇ ⊙ yr − 1 ), whereas lower accretors exhibit only [O I ] and [Ne II ] winds. Together, these results indicate that atomic jets and atomic+molecular winds, consistent with an MHD disk-wind origin, dominate during early, actively accreting disk phases, while at lower accretion rates, jets weaken and winds become predominantly atomic.

Context. Magnetic fields play a crucial role throughout stellar evolution in regulating angular momentum, channelling accretion, and launching jets and outflows. While the magnetic properties of classical T Tauri stars (CTTSs) have been extensively characterised, those of their progenitors, Class I and flat-spectrum (FS) protostars, remain poorly constrained due to their embedded nature, which provides an observational challenge. Aims. Our aim was to detect and characterise the large-scale magnetic fields in a sample of Class I and FS protostars. These young stars are expected to host strong magnetic fields generated by dynamo processes in their largely convective interiors. Methods. We have used SPIRou, a high-resolution spectropolarimeter working in the near-infrared domain, to analyse the polarised light of Class I and FS protostars. We used the least-squares deconvolution (LSD) technique to perform the magnetic analysis and measure the longitudinal magnetic fields from circularly polarised Stokes V profiles. Results. We report new large-scale magnetic field detections in five FS protostars. Including the previous detection of the large-scale magnetic-field in the V347 Aur FS-protostar, 40% of our final sample of 15 protostars is confirmed to be magnetic. These magnetic stars show clear Zeeman signatures, with longitudinal field strengths ranging from ∼80 to ∼200 G in absolute value. The remaining stars exhibit no detectable Stokes V signature, but the estimated upper limits on a hidden dipolar field range from 500 G to more than 5 kG. For stars in which no magnetic fields are detected, it is still conceivable that a magnetic field exists, but is intrinsically weak, highly complex and dominated by small-scale structures, or cancelled out in integrated spectropolarimetric signals due to opposing polarities. Conclusions. We show that Class I and FS protostars can host large-scale magnetic fields with strengths that may be weaker than in more evolved CTTSs. This supports the idea that magnetic processes are already active during the main accretion phase and may influence star–disk interactions from the earliest stages.

We analyze the H ₂ emission observed in the HH 46 Class I system as part of PROtostellar JEts Cradle Tested with JWST (PROJECT-J), to investigate the origin and excitation of the warm molecular outflow. We used NIRSpec and MIRI spectral maps (1.6–27.9 μ m) to trace the structure and physical conditions of the outflow. By fitting the H ₂ rotational diagrams with a multitemperature gas model, we derived key physical parameters, including temperature, extinction, column densities, and the ortho-to-para ratio. This information is combined with a detailed kinematical analysis and comparison with irradiated shock models. We find no evidence of H ₂ temperature or velocity stratification from the axis to the edge of the outflow, as would be expected in MHD disk-wind models and as observed in other outflows. Instead, the observations suggest that the H ₂ emission arises from shock interactions of jet bow shocks and/or wide-angle winds with the ambient medium and cavity walls. NIRSpec emission and velocity maps reveal expanding molecular shells, likely driven by the less luminous source in the binary system. We infer an accretion rate of ≲10 ⁻⁹ M _⊙ yr ⁻¹ for the secondary source, approximately one order of magnitude lower than that of the primary. The H ₂ emission is consistent with excitation by low-velocity (∼10 km s ⁻¹ ) J-type shocks, irradiated by an external UV field that may originate from strong dissociative shocks driven by the atomic jet. Future JWST observations will further constrain the evolution of the expanding shell and the mechanisms driving the outflow.

Context . The ALMA image of the ringed disk around HL Tau stands out as the iconic signature of planet formation, but the origin of the observed substructures is still debated. The HL Tau system also drives a powerful bipolar wind, detected in atomic and molecular lines, that may have important feedback on the process. Aims . The outermost component of the wind traced by CO emission was analyzed in detail to determine its relationship with the disk and its substructures. Methods . A spectro-imaging investigation was conducted using ALMA observations of the ¹² CO (2-1) line at 1.3 mm, with 0.2 km s ⁻¹ and ~0 _⋅ ′′28 spectral and angular resolution, in the framework of the ALMA-DOT project. The relevant wind parameters were derived, allowing a tomographic reconstruction of the morphology and kinematics of the redshifted lobe of the outflow to be compared with theoretical models. Results . The data channel maps and position-velocity diagrams show a rich substructure of concatenated bubble- and arc-shaped features, whose size and distance from the source continuously increase with velocity. The superposition of such features generates the apparent conical shape. The spatial-kinematic properties suggest that the flow presents distinct nested shells with higher propagation speed and steeper speed gradient with distance from the source for shells progressively closer to the axis, and rotating in the same direction as the disk. The wind parameters were compared with the predictions of magnetohydrodynamic (MHD) disk winds. Under this hypothesis, the launch radii of the three outermost shells are found to correspond to the positions of three rings in the dust emission distribution of the disk located at 58, 72, and 86 astronomical units from the star. We derive a magnetic lever arm λ ~ 4–5, higher than that commonly adopted in models of MHD winds from the outer disk. Interpretations are discussed. Conclusions . The properties of the CO outflow from HL Tau appear to be compatible with magnetized disk winds with launch radii in the region at 50–90 au from the source. As such, the wind may be capable of removing angular momentum also from the outer disk. The arrangement of the wind in nested shells with brighter emission rooted at the location of ring substructures could support the results of recent non-ideal MHD simulations according to which magnetic instabilities can spontaneously generate both the ring–gap system and a connected inhomogeneous layered wind, alternatively to the action of protoplanets. Further observational analyses and comparisons with other classes of models will help establish the role of magnetic effects in the process of planet formation.

Context . The accretion luminosity ( L _acc ) in young, low-mass stars is crucial for understanding stellar formation. However, obtaining direct measurements is often hindered by limited spectral coverage and challenges in UV-excess modeling. Empirical relations linking L _acc to various accretion tracers are widely used to overcome these limitations. Aims . This work revisits these empirical relations using the PENELLOPE dataset, evaluating their applicability across different star-forming regions as well as accreting young objects other than Classical T Tauri Stars (CTTSs; Class II sources). Methods . We analyzed the PENELLOPE VLT/X-shooter dataset of 64 CTTSs, measuring fluxes of several accretion tracers and adopting the stellar and accretion parameters derived from studies based on PENELLOPE. For 61 sources, we supplemented our analysis with the ODYSSEUS HST data set, which covers a wider spectral range in NUV bands. Results . We compared the L _acc values obtained in the PENELLOPE and ODYSSEUS surveys, which employed a single hydrogen slab model (XS-fit) and a multi-column accretion shock model (HST-fit), respectively, and found statistically consistent results. Our analysis confirms that existing empirical relations, previously derived for the Lupus sample, provide reliable L _acc estimates for CTTSs in several other star-forming regions. We revisit empirical relations for accretion tracers in our dataset, based on HST-fit, with coefficients which are consistent within 1 σ with XS-fit results for most lines. We also propose a method to estimate extinction using these relations and investigate the empirical relations for Brackett lines (Br8 to Br21). Conclusions . The L _acc − L _line empirical relations can be successfully used for statistical studies of accretion on young forming objects in different star-forming regions. These relations also offer a promising approach to independently estimate extinction in CTTSs, provided a sufficient number of flux-calibrated tracers are available across a broad spectral range. We confirm that near-infrared lines (Pa β and Br γ ) serve as reliable tracers of L _acc in high accretors, making them valuable tools for probing accretion properties of high accreting young stars not accessible in the UVB.

The properties of stars and planets are shaped by the initial conditions of their natal clouds. However, the spatial scales over which the initial conditions can exert a significant influence are not well constrained. We report the first evidence for parsec-scale spatial correlations of stellar magnetospheric inclinations ( i _mag ), observed in the Lupus low-mass star-forming region. Applying consensus clustering with a hierarchical density-based clustering algorithm, we demonstrate that the detected spatial dependencies are stable against perturbations by measurement uncertainties. The i _mag correlation scales are on the order of ∼3 pc, which aligns with the typical scales of the Lupus molecular cloud filaments. Our results reveal a connection between large-scale forces—in the form of expanding shells from the Upper Scorpius and Upper Centaurus–Lupus regions—and sub-au-scale system configurations. We find that Lupus has a nonuniform i _mag distribution and suggest that this results from the preferential elongation of protostellar cores along filamentary axes. Nonuniformity would have significant implications for exoplanet occurrence rate calculations, so future work should explore the longevity of these biases driven by the star–cloud connection.

We present JWST NIRSpec spectroimaging observations of jets from four edge-on protoplanetary disks that exhibit clear signatures of MHD disk winds. Bipolar jets are detected and spatially resolved in over 30 shock-excited forbidden lines, multiple Paschen and Brackett series lines of atomic hydrogen, and the high-energy excitation line of atomic helium (1.083 μm). This helium line is the brightest jet tracer toward HH 30 and FS TauB, which also exhibit asymmetric intensity between their red- and blueshifted lobes in all tracers, including the [Fe ii] and He i lines. Extinction maps reveal no significant differences across the lobes, suggesting an asymmetric jet-launching mechanism rather than environmental effects. Diagnostic line ratios yield consistent shock speeds of 50–60 km s⁻¹, jet ionization fractions of 0.1–0.2, and pre-shock electron densities of 1000 cm⁻³. Combined with pixel-by-pixel electron density maps and [Fe ii] line luminosities, we estimate jet mass-loss rates using three independent methods, averaging around a few 10⁻⁹ M _⊙ yr⁻¹. We estimate the accretion rates for these sources as 10× the jet mass-loss rates and find them to match well with the independently derived accretion estimates of other Class II sources in the Taurus star-forming region. Owing to JWST’s high precision, we also investigate jet wiggling and find Tau 042021 to showcase the perfect case of mirror-symmetric wiggling, which can only be explained by the motion of the jet source around a stellar companion. Modeling this wiggling suggests Tau 042021 to host a 0.33 and 0.07 M _⊙ binary at the center with a binary separation of 1.35 au and an orbital period of 2.5 yr.

We present JWST NIRSpec spectro-imaging observations of jets from four edge-on protoplanetary disks that exhibit clear signatures of MHD disk winds. Bipolar jets are detected and spatially resolved in over 30 shock-excited forbidden lines, multiple Paschen and Brackett series lines of atomic hydrogen, and the high-energy excitation line of atomic helium (1.083 um). This helium line is the brightest jet-tracer towards HH 30 and FS TauB, which also exhibit asymmetric intensity between their red- and blue-shifted lobes in all tracers, including the [Fe II] and [He I] lines. Extinction maps reveal no significant differences across the lobes, suggesting an asymmetric jet-launching mechanism rather than environmental effects. Diagnostic line ratios yield consistent shock speeds of 50-60 km/s, jet ionization fractions of 0.1-0.2, and pre-shock electron densities of 1000 /cm^3. Combined with pixel-by-pixel electron density maps and [Fe II] line luminosities, we estimate jet mass-loss rates using three independent methods, averaging around a few 10^(-9) solar masses/yr. We estimate the accretion rates for these sources as 10 times the jet mass loss rates and find them to match well with the independently derived accretion estimates of other Class II sources in the Taurus star-forming region. Owing to JWST's high precision, we also investigate jet wiggling and find Tau 042021 to showcase the perfect case of mirror-symmetric wiggling, which can only be explained by the motion of the jet source around a stellar companion. Modeling this wiggling suggests Tau 042021 to host 0.33 and 0.07 solar masses binary at the center with binary separation of 1.35 au and an orbital period of 2.5 years.