This paper presents a deep MIRI/JWST medium-resolution spectroscopy (MRS) covering the rest-frame optical spectrum of the GN-z11 galaxy. The [O III] 5008 & Aring; and H alpha emission lines are detected and spectroscopically resolved. The line profiles are well modeled by a narrow Gaussian component with intrinsic full widths at half maximum of 189 +/- 25 and 231 +/- 52 km s(-1), respectively. We do not find any evidence of a dominant broad H alpha emission line component tracing a broad-line region in a type 1 active galactic nucleus (AGN). The existence of an accreting black hole dominating the optical continuum and emission lines of GN-z11 is not compatible with the measured H alpha and [O III] 5008 & Aring; luminosities. If the well-established relations for low-z AGNs apply in GN-z11, the [O III] 5008 & Aring; and H alpha luminosities would imply extremely high super-Eddington ratios (lambda(E) > 290), and bolometric luminosities similar to 20 times those derived from the UV/optical continuum. However, a broad (similar to 430-470 km s(-1)) and weak (< 20-30%) H alpha line component, tracing a minor AGN contribution in the optical, cannot be completely ruled out with the sensitivity of the current data. The physical and excitation properties of the ionized gas are consistent with a low-metallicity starburst with a star formation rate of 24 +/- 3 M-circle dot yr(-1). The electron temperature of the ionized gas is T-e (O++) = 14 000 +/- 2100 K, while the direct-T-e gas-phase metallicity is 12 + log(O/H) = 7.91 +/- 0.07 (Z = 0.17 +/- 0.03 Z(circle dot)). The optical line ratios locate GN-z11 in the starburst or AGN region, but they are more consistent with those of local low-metallicity starbursts and high-z luminous galaxies detected at redshifts similar to GN-z11. We conclude that the MRS optical spectrum of GN-z11 is consistent with that of a massive, compact, and low-metallicity starburst galaxy. Its high star formation and stellar mass surface densities are close to those of the densest stellar clusters, and we therefore speculate that GN-z11 might undergo a feedback-free, highly efficient starburst phase. Additional JWST data are needed to validate this scenario and other recently proposed alternatives to explain the existence of bright compact galaxies in the early Universe.

Context. Galaxy mergers are an important and complex phase during the evolution of galaxies. They may trigger nuclear activity and/or strong star forming episodes in galaxy centres that potentially alter the evolution of the system. Aims. As part of the guaranteed time observations program Mid-Infrared Characterization Of Nearby Iconic galaxy Centers (MICONIC), we used the medium-resolution spectrometer (MRS) of the Mid-Infrared Instrument on board the James Webb Space Telescope (JWST) to study NGC 6240. We aim to characterise the dual active galactic nuclei (AGN), the ionised gas outflows, and the main properties of the interstellar medium over a mapped area of 6.6 '' x 7.7 ''. Aims. We obtained integral field spectroscopic mid-infrared data (wavelength from 4.9 to 28 mu m) of NGC 6240. We modelled the emission lines through a kinematic decomposition that accounts for the possible existence of various components. Methods. We have resolved both nuclei of NGC 6240 for the first time in the full 5-28 mu m spectral range. The fine structure lines in the southern (S) nucleus are broader than for the northern (N) nucleus (full width at half maximum of >= 1500 versus similar to 700 km s(-1) on average, respectively). High excitation lines, such as [Ne V], [Ne VI], and [Mg V], are clearly detected in the N nucleus. In the S nucleus, the same lines can be detected but only after a decomposition of the polycyclic aromatic hydrocarbon features in the integrated spectrum, due to a combination of a strong mid-IR continuum, broad emission lines, and intense star formation (SF). The SF is distributed all over the mapped field of view of 3.5 kpc x 4.1 kpc (projected), with the maximum located around the S nucleus. Both nuclear regions appear to be connected by a bridge region that is detected with all the emission lines. Based on the observed MRS line ratios and the high velocity dispersion (sigma similar to 600 km s(-1)), shocks also dominate the emission in this system. We detected the presence of outflows as a bubble north-west from the N nucleus and at the S nucleus. We estimated an ionised mass outflow rate of 1.4 +/- 0.3 M-circle dot yr(-1) and 1.8 +/- 0.2 M-circle dot yr(-1), respectively. Given the derived kinetic power of these outflows, both the AGN and the starburst could have triggered them.

Context. Thanks to decades of observations using the Hubble Space Telescope (HST), the structure of galaxies at redshift z>2 has been widely studied in the rest-frame ultraviolet regime, which traces recent star formation from young stellar populations. However, we still have little information about the spatial distribution of the older, more evolved stellar populations, constrained by the rest-frame infrared portion of the galaxies' spectral energy distribution. Aims. We present the morphological characterization of a sample of 49 massive galaxies (log(M-star/M-circle dot)>9) at redshift 33 massive galaxies show a smooth distribution of their rest-infrared light, strongly supporting the increasing number of regular disk galaxies already in place at early epochs. These results are further reinforced by the analysis of JWST/NIRCam data at 4.4 mu m. On the contrary, the ultraviolet structure obtained from HST/WFC3 and JWST/NIRCam observations at similar to 1.5 mu m is generally more irregular, catching the most recent episodes of star formation. Importantly, we find a segregation of morphologies across cosmic time, where galaxies at redshift z>3.75 show later-type morphologies compared to z similar to 3 galaxies. These findings suggest a transition phase in galaxy assembly and central mass build-up, which takes place already at z similar to 3-4. Conclusions. The combined analysis of NIRCam and MIRI imaging datasets allows us to prove that the rest-frame near-infrared morphology of massive galaxies at cosmic noon is typical of compact disk galaxies with a smooth mass distribution.A

Dusty star-forming galaxies (DSFGs) at z > 2 have been commonly observed in overdense regions, where the merging processes and large halo masses induce rapid gas accretion, triggering star formation rates (SFRs) up to similar to 1000 M-circle dot yr(-1). Despite the importance of these DSFGs for understanding star formation in the early Universe, their stellar distributions, traced by the near-infrared (near-IR) emission, had remained spatially unresolved until the arrival of the JWST. In this work, we present, for the first time, a spatially resolved morphological analysis of the rest-frame near-IR (similar to 1.1-3.5 mu m) emission in DSFGs traced with the JWST/MIRI F560W, F770W, F1280W, and F1800W filters. In particular, we studied the mature stellar component for the three DSFGs and a Lyman-break galaxy (LBG) present in an overdensity at z = 4.05. Moreover, we used these rest-frame near-IR images along with ultraviolet (UV) and (sub)-mm ancillary photometric data to model their spectral energy distributions (SEDs) and extract their main physical properties (e.g. M*, SFR, A(V)). The sub-arcsec resolution images from the JWST have revealed that the light distributions in these galaxies present a wide range of morphologies, from disc-like to compact and clump-dominated structures. Two DSFGs and the LBG are classified as late-type galaxies (LTGs) according to non-parametric morphological indices, while the remaining DSFG is an early-type galaxy (ETG). These near-IR structures contrast with their ultraviolet emission, which is diffuse and, in GN20 and GN20.2b, off-centred by similar to 4 kpc. This result suggests that star formation takes place across the entire galaxy, while the UV light traces only those regions where the otherwise high internal extinction decreases significantly. The SED fitting analysis yields large SFRs (similar to 300-2500 M-circle dot yr(-1)), large stellar masses (M* = (0.24-1.79) x 1011 M-circle dot), and high integrated extinction values (AV = 0.8-1.5 mag) for our galaxies. In particular, we observe that GN20 dominates the total SFR with a value 2550 +/- 150 M-circle dot yr(-1), while GN20.2b has the highest stellar mass (M* = (2.2 +/- 1.4) x 1011 M-circle dot). The two DSFGs classified as LTGs (GN20 and GN20.2a) have a high specific SFR (sSFR > 30 Gyr(-1)), placing them above the star-forming main sequence (SFMS) at z similar to 4 by similar to 0.5 dex; whereas the ETG (i.e. GN20.2b) is compatible with the high-mass end of the main sequence. In comparison with other DSFGs in overdensities at z similar to 2-7, we observe that our objects present similar SFRs, depletion times, and projected separations. Nevertheless, the sizes computed for GN20 and GN20.2a are up to two times larger than those of isolated galaxies observed in CEERS and ALMA-HUDF at similar redshifts. We interpret this difference in size as an effect of rapid growth induced by the dense environment.

We use the James Webb Space Telescope (JWST) and its Mid-Infrared Instrument (MIRI) (5-28 um), to study the embedded HH 211 flow. We map a 0.95'x0.22' region, covering the full extent of the blue-shifted lobe, the central protostellar region, and a small portion of the red-shifted lobe. The jet driving source is not detected even at the longest mid-IR wavelengths. The overall morphology of the flow consists of a highly collimated jet, mostly molecular (H2, HD) with an inner atomic ([FeI], [FeII], [SI], [NiII]) structure. The jet shocks the ambient medium, producing several large bow-shocks, rich in forbidden atomic and molecular lines, and is driving an H2 molecular outflow, mostly traced by low-J, v=0 transitions. Moreover, 0-0 S(1) uncollimated emission is also detected down to 2"-3" ( 650-1000 au) from the source, tracing a cold (T=200-400 K), less dense and poorly collimated molecular wind. The atomic jet ([FeII] at 26 um) is detected down to 130 au from source, whereas the lack of H2 emission close to the source is likely due to the large visual extinction. Dust continuum-emission is detected at the terminal bow-shocks, and in the blue- and red-shifted jet, being likely dust lifted from the disk. The jet shows an onion-like structure, with layers of different size, velocity, temperature, and chemical composition. Moreover, moving from the inner jet to the outer bow-shocks, different physical, kinematic and excitation conditions for both molecular and atomic gas are observed. The jet mass-flux rate, momentum, and momentum flux of the warm H2 component are up to one order of magnitude higher than those inferred from the atomic jet component. Our findings indicate that the warm H2 component is the primary mover of the outflow, namely it is the most significant dynamical component of the jet, in contrast to jets from more evolved YSOs, where the atomic component is dominant.

With a temperature of ∼ 285 K WISE0855 is the coldest brown dwarf observed so far. Using the James Webb Space Telescope (JWST) we obtained observations that allow us to characterize WISE0855s atmosphere focusing on vertical variation in the water steam abundance, measuring trace gas abundances and receiving bulk parameters for this cold object. We observed the ultra cool dwarf WISE0855 using the Mid-Infrared Instrument Medium Resolution Spectrometer (MIRI/MRS) onboard JWST at a spectral resolution of up to 3750. We combined the observation with published data from the Near Infrared Spectrograph (NIRSpec) G395M and PRISM modes yielding a spectrum ranging from 0.8 to 22 um. We apply atmospheric retrievals using petitRADTRANS to measure atmospheric abundances, the pressure-temperature structure, radius and gravity of the brown dwarf. We also employ publicly available clear and cloudy self-consistent grid models to estimate bulk properties of the atmosphere such as the effective temperature, radius, gravity and metallicity. Atmospheric retrievals constrain a variable water abundance profile in the atmosphere, as predicted by equilibrium chemistry. We detect the 15NH3 isotopologue and infer a ratio of mass fraction of 14NH3/15NH3 = 332+63-43 for the clear retrieval. We measure the bolometric luminosity by integrating the presented spectrum and obtain a value of log(L/L_⊙) = -7.291+/-0.008. The detected water depletion indicates that water condenses out in the upper atmosphere due to the very low effective temperature of WISE0855. The height in the atmosphere where this occurs is covered by the MIRI/MRS data, and thus demonstrates the potential of MIRI to characterize cold gas giants atmospheres. Comparing the data to retrievals and self-consistent grid models, we do not detect signs for water ice clouds, although their spectral features have been predicted in previous studies.

We present MIRI/JWST medium-resolution spectroscopy (MRS) and imaging (MIRIM) of the lensed galaxy MACS1149-JD1 at a redshift of $z$\,=\,9.1092pm 0.0002, when the Universe was about 530 Myr old. We detect, for the first time, spatially resolved Halpha emission in a galaxy at a redshift above nine. The structure of the Halpha emitting gas consists of two clumps, S and N, carrying about $60$ and $40$ of the total flux, respectively. The total Halpha luminosity implies an instantaneous star-formation rate in the range of 3.2\,pm \,0.3 and 5.3\,pm odot $ for sub-solar and solar metallicities. The ionizing photon production efficiency, $ ion )$, shows a spatially resolved structure with values of 25.55\,pm \,0.03; 25.47\,pm \,0.03; and 25.91\,pm $ for the integrated galaxy and clumps S and N, respectively. The Halpha rest-frame equivalent width, EW$_ $\,(Halpha ), is $\,AA for the integrated galaxy, but it presents extreme values of and geq 1951\,AA for clumps S and N, respectively. The spatially resolved ionizing photon production efficiency is within the range of values measured in galaxies at a redshift above six and well above the canonical value (25.2\,pm $). The EW$_ $\,(Halpha ) is a factor of two lower than the predicted value at $z$\,=\,9.11 based on the extrapolation of the evolution of the $\,(Halpha ) with redshifts, propto $, including galaxies detected with JWST. The extreme difference of the EW$_ $\,(Halpha ) for clumps S and N indicates the presence of a recent (<5 Myr) stellar burst in clump N and a star formation over a larger period of time (e.g., sim 50 Myr) in clump S. The different ages of the stellar population place MACS1149-JD1 and clumps N and S at different locations in the log($ ion $) to EW$_ $\,(Halpha ) plane and above the main relation defined from intermediate- and high-redshift (z=3-7) galaxies detected with JWST. Finally, clump S and N show very different Halpha kinematics, with velocity dispersions of 56\,pm $ and 113\,pm $, likely indicating the presence of outflows or increased turbulence in clump N. The dynamical mass $M_ dyn $= (2.4\,pm \,0.5)\,times odot $, obtained from the size of the integrated Halpha ionized nebulae and its velocity dispersion, is within the range previously measured with the spatially resolved OIII 88mu m line.

Dusty star-forming galaxies emit most of their light at far-infrared to millimeter wavelengths as their star formation is highly obscured. Far-infrared and millimeter observations have revealed their dust, neutral and molecular gas properties. The sensitivity of JWST at rest-frame optical and near-infrared wavelengths now allows the study of the stellar and ionized gas content. We investigate the spatially resolved distribution and kinematics of the ionized gas in GN20, a dusty star-forming galaxy at z = 4.0548. We present deep MIRI/MRS integral field spectroscopy of the near-infrared rest-frame emission of GN20. We detect spatially resolved Paα, out to a radius of 6 kpc, distributed in a clumpy morphology. The star formation rate derived from Paα (144 ± 9 M⊙ yr−1) is only 7.7 ± 0.5% of the infrared star formation rate (1860 ± 90 M⊙ yr−1). We attribute this to very high extinction (AV = 17.2 ± 0.4 mag, or AV, mixed = 44 ± 3 mag), especially in the nucleus of GN20, where only faint Paα is detected, suggesting a deeply buried starburst. We identify four, spatially unresolved, clumps in the Paα emission. Based on the double peaked Paα profile, we find that each clump consists of at least two sub-clumps. We find mass upper limits consistent with them being formed in a gravitationally unstable gaseous disk. The ultraviolet bright region of GN20 does not have any detected Paα emission, suggesting an age of more than 10 Myr for this region of the galaxy. From the rotation profile of Paα, we conclude that the gas kinematics are rotationally dominated and the vrot/σm = 3.8 ± 1.4 is similar to low-redshift luminous infrared galaxies. From the Paα kinematics, we cannot distinguish between a rotational profile of a large disk and a late stage merger mimicking a disk. We speculate that GN20 is in the late stage of a major merger, where the clumps in a large gas-rich disk are created by the major merger, while the central starburst is driven by the merger event.

Context. Due to the high visual extinction and lack of sensitive mid-infrared (MIR) telescopes, the origin and properties of outflows and jets from embedded Class 0 protostars are still poorly constrained. Aims. We aim to characterise the physical, kinematic, and dynamical properties of the HH 211 jet and outflow, one of the youngest protostellar flows. Methods. We used the James Webb Space Telescope (JWST) and its Mid-InfraRed Instrument (MIRI) in the 5-28 mu m range to study the embedded HH 211 flow. We mapped a 0 '.95 x 0 '.22 region, covering the full extent of the blueshifted lobe, the central protostellar region, and a small portion of the redshifted lobe. We extracted spectra along the jet and outflow and constructed line and excitation maps of both atomic and molecular lines. Additional JWST NIRCam H-2 narrow-band images (at 2.122 and 3.235 mu m) provide a visualextinction map of the whole flow, and are used to deredden our data. Results. The jet-driving source is not detected even at the longest MIR wavelengths. The overall morphology of the flow consists of a highly collimated jet, which is mostly molecular (H-2, HD) with an inner atomic ([Fe I], [Fe II], [S I], [Ni II]) structure. The jet shocks the ambient medium, producing several large bow shocks (BSs) that are rich in forbidden atomic ([Fe II], [S I], [Ni II], [Cl I], [Cl II], [Ar II], [Co II], [Ne II], [S III]) and molecular lines (H-2, HD, CO, OH, H2O, CO2, HCO+), and is driving an H-2 molecular outflow that is mostly traced by low- J, v = 0 transitions. Moreover, H-2 0-0 S(1) uncollimated emission is also detected down to 2 ''-3 '' (similar to 650-1000 au) from the source, tracing a cold (T=200-400 K), less dense, and poorly collimated molecular wind. Two H-2 components (warm, T =300-1000 K, and hot, T =1000-3500 K) are detected along the jet and outflow. The atomic jet ([Fe II] at 26 mu m) is detected down to similar to 130 au from the source, whereas the lack of H-2 emission (at 17 mu m) close to the source is likely due to the large visual extinction (A(V) > 80 mag). Dust-continuum emission is detected at the terminal BSs and in the blue- and redshifted jet, and is likely attributable to dust lifted from the disc. Conclusions. The jet shows an onion-like structure, with layers of different size, velocity, temperature, and chemical composition. Moreover, moving from the inner jet to the outer BSs, different physical, kinematic, and excitation conditions for both molecular and atomic gas are observed. The mass-flux rate and momentum of the jet, as well as the momentum flux of the warm H-2 component, are up to one order of magnitude higher than those inferred from the atomic jet component. Our findings indicate that the warm H-2 red component is the main driver of the outflow, that is to say it is the most significant dynamical component of the jet, in contrast to jets from more evolved YSOs, where the atomic component is dominant.

Context . Complex organic molecules (COMs) are ubiquitously detected in the gas phase and thought to be mostly formed on icy grains. Nevertheless, there have not been any unambiguous detections of COMs larger than CH 3 OH in ices reported thus far. Exploring this matter in greater detail has now become possible with the unprecedented possibilities offered by the James Webb Space Telescope (JWST) within the infrared (IR) spectral range with its very high sensitivity and spectral resolution in the critical 5–10 µm range, the fingerprint region of oxygen-bearing COMs. Aims . In the JWST Observations of Young protoStars (JOYS+) program, more than 30 protostars are undergoing observation with the Medium Resolution Spectrograph (MRS) of the Mid-IR Instrument (MIRI). The goal of this study is to comprehensively explore the COMs ice signatures in one low- and one high-mass protostar: NGC 1333 IRAS 2A and IRAS 23385+6053, respectively. Methods . We performed global continuum and silicate subtractions of the MIRI-MRS spectra, followed by a local continuum subtraction in optical depth scale in the range around 6.8 and 8.6 µm, the ice COM fingerprint region. We explored different choices for the local continuum and silicate subtraction. Next, we fit the observational data with a large sample of available IR laboratory ice spectra. We used the ENIIGMA fitting tool, a genetic algorithm-based code that not only finds the best fit between the lab data and the observations, but also performs a statistical analysis of the solutions, such as deriving the confidence intervals and quantifying fit degeneracy. Results . We report the best fits for the spectral ranges between 6.8 and 8.6 µm in NGC 1333 IRAS 2A and IRAS 23385+6053, originating from simple molecules and COMs, as well as negative ions. Overall, we find that ten chemical species are needed to reproduce the astronomical data. The strongest feature in this range (7.7 µm) is dominated by CH 4 , with contributions from SO 2 and OCN − . Our results indicate that the 7.2 and 7.4 µm bands are mostly dominated by HCOO − . We also find statistically robust detections of COMs based on multiple bands, most notably, CH 3 CHO, CH 3 CH 2 OH, and CH 3 OCHO. We also report a likely detection of CH 3 COOH. Based on the ice column density ratios between CH 3 CH 2 OH and CH 3 CHO of NGC 1333 IRAS 2A and IRAS 23385+6053, we find compelling evidence that these COMs are formed on icy grains. Finally, the derived ice abundances for NGC 1333 IRAS 2A correlate well with those in comet 67P/GC within a factor of 5. Conclusions . Based on the high-quality JWST (MIRI-MRS) spectra, we conclude that COMs are present in interstellar ices, thus providing additional proof for the solid-state origin of these species in star-forming regions. In addition, the good correlation between the ice abundances in comet 67P and NGC 1333 IRAS 2A is fully in line with the idea that cometary COMs may be inherited from the early protostellar phases to a significant extent.

The MIRI-MRS instrument onboard JWST allows for probing the molecular gas composition at mid-IR wavelengths at unprecedented resolution and sensitivity. It is important to study these features in low-mass embedded protostellar systems since the formation of planets is thought to start in this phase. We present JWST/MIRI-MRS data of 18 low-mass protostellar systems in the JOYS program, focusing on gas-phase molecular lines in spectra extracted from the central protostellar positions. Besides H2, the most commonly detected molecules are H2O, CO2, CO, and OH. Other molecules such as 13CO2, C2H2, 13CCH, HCN, C4H2, CH4, and SO2 are detected only toward at most three of the sources. The JOYS data also yield the surprising detection of SiO gas toward two sources (BHR71-IRS1, L1448-mm) and for the first time CS and NH3 at mid-IR wavelengths toward a low-mass protostar (B1-c). The temperatures derived for the majority of the molecules are 100-300 K, much lower than what is typically derived toward more evolved Class II sources (>500 K). Toward three sources (e.g., TMC1-W), hot ( 1000 K) H2O is detected, indicative of the presence of hot molecular gas in the embedded disks, but such warm emission from other molecules is absent. The agreement in abundance ratios with respect to H2O between ice and gas point toward ice sublimation in a hot core for a few sources (e.g., B1-c) whereas their disagreement and velocity offsets hint at high-temperature (shocked) conditions toward other sources (e.g., L1448-mm, BHR71-IRS1). The typical temperatures of the gas-phase molecules of 100-300 K are consistent with both ice sublimation in hot cores as well as high-temperature gas phase chemistry. Molecular features originating from the inner embedded disks are not commonly detected, likely because they are too extincted even at mid-IR wavelengths by small not-settled dust grains in upper layers of the disk.

Context. Due to the high visual extinction and lack of sensitive mid-infrared (MIR) telescopes, the origin and properties of outflows and jets from embedded Class 0 protostars are still poorly constrained. Aims. We aim to characterise the physical, kinematic, and dynamical properties of the HH 211 jet and outflow, one of the youngest protostellar flows. Methods. We used the James Webb Space Telescope (JWST) and its Mid-InfraRed Instrument (MIRI) in the 5–28 µm range to study the embedded HH 211 flow. We mapped a 0′.95 × 0′.22 region, covering the full extent of the blueshifted lobe, the central protostellar region, and a small portion of the redshifted lobe. We extracted spectra along the jet and outflow and constructed line and excitation maps of both atomic and molecular lines. Additional JWST NIRCam H2 narrow-band images (at 2.122 and 3.235 µm) provide a visualextinction map of the whole flow, and are used to deredden our data. Results. The jet-driving source is not detected even at the longest MIR wavelengths. The overall morphology of the flow consists of a highly collimated jet, which is mostly molecular (H2, HD) with an inner atomic ([Fe I], [Fe II], [S I], [Ni II]) structure. The jet shocks the ambient medium, producing several large bow shocks (BSs) that are rich in forbidden atomic ([Fe II], [S I], [Ni II], [Cl I], [Cl II], [Ar II], [Co II], [Ne II], [S III]) and molecular lines (H2, HD, CO, OH, H2O, CO2, HCO+), and is driving an H2 molecular outflow that is mostly traced by low- J, v = 0 transitions. Moreover, H2 0-0 S(1) uncollimated emission is also detected down to 2″-3″ (~650–1000 au) from the source, tracing a cold (T=200–400 K), less dense, and poorly collimated molecular wind. Two H2 components (warm, T =300–1000 K, and hot, T =1000–3500 K) are detected along the jet and outflow. The atomic jet ([Fe II] at 26 µm) is detected down to ~130 au from the source, whereas the lack of H2 emission (at 17 µm) close to the source is likely due to the large visual extinction (AV > 80 mag). Dust-continuum emission is detected at the terminal BSs and in the blue- and redshifted jet, and is likely attributable to dust lifted from the disc. Conclusions. The jet shows an onion-like structure, with layers of different size, velocity, temperature, and chemical composition. Moreover, moving from the inner jet to the outer BSs, different physical, kinematic, and excitation conditions for both molecular and atomic gas are observed. The mass-flux rate and momentum of the jet, as well as the momentum flux of the warm H2 component, are up to one order of magnitude higher than those inferred from the atomic jet component. Our findings indicate that the warm H2 red component is the main driver of the outflow, that is to say it is the most significant dynamical component of the jet, in contrast to jets from more evolved YSOs, where the atomic component is dominant.

Very-low-mass stars (those less than 0.3 solar masses) host orbiting terrestrial planets more frequently than other types of stars. The compositions of those planets are largely unknown but are expected to relate to the protoplanetary disk in which they form. We used James Webb Space Telescope mid-infrared spectroscopy to investigate the chemical composition of the planet-forming disk around ISO-ChaI 147, a 0.11-solar-mass star. The inner disk has a carbon-rich chemistry; we identified emission from 13 carbon-bearing molecules, including ethane and benzene. The high column densities of hydrocarbons indicate that the observations probe deep into the disk. The high carbon-to-oxygen ratio indicates radial transport of material within the disk, which we predict would affect the bulk composition of any planets forming in the disk.

The increasing complexity and scope of thoracic surgery warrants tools to monitor and improve the quality of care provided to patients. Unlike in cardiac surgery, little data on the volume or outcome of thoracic surgical procedures are currently collected. The Australia and Aotearoa New Zealand Thoracic Registry (ANZTHOR) steering group has sought to rectify this by designing a thoracic clinical quality registry, with improved patient care as its central goal.

The formation of stars and planets is accompanied not only by the build-up of matter, namely accretion, but also by its expulsion in the form of highly supersonic jets that can stretch for several parsecs 1 , 2 . As accretion and jet activity are correlated and because young stars acquire most of their mass rapidly early on, the most powerful jets are associated with the youngest protostars 3 . This period, however, coincides with the time when the protostar and its surroundings are hidden behind many magnitudes of visual extinction. Millimetre interferometers can probe this stage but only for the coolest components 3 . No information is provided on the hottest (greater than 1,000 K) constituents of the jet, that is, the atomic, ionized and high-temperature molecular gases that are thought to make up the jet’s backbone. Detecting such a spine relies on observing in the infrared that can penetrate through the shroud of dust. Here we report near-infrared observations of Herbig-Haro 211 from the James Webb Space Telescope, an outflow from an analogue of our Sun when it was, at most, a few times 10 4 years old. These observations reveal copious emission from hot molecules, explaining the origin of the ‘green fuzzies’ 4 – 7 discovered nearly two decades ago by the Spitzer Space Telescope 8 . This outflow is found to be propagating slowly in comparison to its more evolved counterparts and, surprisingly, almost no trace of atomic or ionized emission is seen, suggesting its spine is almost purely molecular.

Using MIRI on-board JWST we present mid-infrared sub-arcsec imaging (MIRIM) and spectroscopy (MRS) of the hyperluminous infrared system SPT0311-58 at z=6.9. MIRI observations are compared with existing ALMA far-infrared continuum and [CII]158$\mu$m imaging. Even though the ALMA observations suggests very high star formation rates (SFR) in the eastern (E) and western (W) galaxies of the system, the H$\alpha$ line is not detected. This, together with the detection of the Pa$\alpha$ line, implies very high optical nebular extinction with lower limits of 4.2 (E) and 3.9 mag (W), and even larger 5.6 (E) and 10.0 (W) for SED derived values. The extinction-corrected Pa$\alpha$ SFRs are 383 and 230M$_{\odot}$yr$^{-1}$ for the E and W galaxies, respectively. This represents 50% of the SFRs derived from the [CII]158$\mu$m line and infrared light for the E galaxy and as low as 6% for the W galaxy. The MIRI observations reveal a clumpy stellar structure, with each clump having 3 to 5 $\times$10$^{9}$M$_\mathrm{\odot}$, leading to a total stellar mass of 2.0 and 1.5$\times$10$^{10}$M$_\mathrm{\odot}$ for the E and W galaxies, respectively. The specific SFR in the stellar clumps ranges from 25 to 59Gyr$^{-1}$, which are 3 to 10 times larger than the values measured in galaxies of similar mass at redshifts 6 to 8. The overall gas mass fraction is $M_\mathrm{gas}$/$M_*\sim3$, similar to that of z=4.5-6 star-forming galaxies. The observed properties of SPT0311-58 such as the clumpy distribution at sub(kpc) scales and the very high average extinction are similar to those observed in low- and intermediate-z LIRGs and ULIRGs, even though SPT0311-58 is observed only 800 Myr after the Big Bang. Massive, heavily obscured, clumpy starburst systems like SPT0311-58 likely represent the early phases in the formation of massive high-z bulge/spheroids and luminous quasars.