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How have planets formed in the Solar System? And what chemical composition they inherited from their natal environment? Is the chemical composition passed unaltered from the earliest stages of the formation of the Sun to its disk and then to the planets which assembled in the disk? Or does it reflects chemical processes occurring in the disk and/or during the planet formation process? And what was the role of comets in the delivery of volatiles and prebiotic compounds to early Earth? A viable way to answer these questions is to observe protoplanetary disks around young Sun-like stars and compare their chemical composition with that of the early Solar System, which is imprinted in comets. The impacting images recently obtained by millimetre arrays of antennas such as ALMA provided the first observational evidence of ongoing planet formation in 0.1-1 million years old disks, through rings and gaps in their dust and gas distribution. The chemical composition of the forming planets and small bodies clearly depends on the location and timescale for their formation and is intimately connected to the spatial distribution and abundance of the various molecular species in the disk. The chemical characterisation of disks is therefore crucial. This field, however, is still in its infancy, because of the small sizes of disks (~100 au) and to the low gas-phase abundance of molecules (abundances with respect to H2 down to 10-12), which requires an unprecedented combination of angular resolution and sensitivity. I will show the first pioneering results obtained as part of the ALMA chemical survey of protoplanetary disks in the Taurus star forming region (ALMA-DOT program). Thanks to the ALMA images at ~20 au resolution, we recovered the radial distribution and abundance of diatomic molecules (CO and CN), S-bearing molecules (CS, SO, SO2, H2CS), as well as simple organics (H2CO and CH3OH) which are key for the formation of prebiotic compounds. Enhanced H2CO emission in the cold outer disk, outside the CO snowline, suggests that organic molecules may be efficiently formed in disks on the icy mantles of dust grain. This could be the dawn of ice chemistry in the disk, producing ices rich of complex organic molecules (COMs) which could be incorporated by the bodies forming in the outer disk region, such as comets. The next step is the comparison of the molecules radial distribution and abundance in disks with the chemical composition of comets, which are the leftover building blocks of giant planet cores and other planetary bodies. The first pioneering results in this direction have been obtained thanks to the ESA’s Rosetta mission, which allowed obtaining in situ measurements of the COMs abundance on the comet 67P/Churyumov-Gerasimenko. The comparison with three protostellar solar analogs observed on Solar System scales has shown comparable COMs abundance, implying that the volatile composition of comets and planetesimals may be partially inherited from the protostellar stage. The advent of new mission, devoted to sample return such as AMBITION will allow us to do a step ahead in this direction.

Whether high-mass stars (M > 7M⊙) emerge from a scaled-up version of the low-mass star formation scenario, i. e. through disk-mediated accretion, is still debated. We present the first results of an observational programme aimed to map the innermost regions of high-mass stellar objects by combining together high-spatial resolution maser and radio continuum observations, and near-infrared imaging.

We have carried out a kinematical, high angular resolution (~01) study of the optical blueshifted flow from DG Tau within 05 from the source (i.e., 110 AU when deprojected along this flow). We analyzed optical emission line profiles extracted from a set of seven long-slit spectra taken with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope, obtained by maintaining the slit parallel to the outflow axis while at the same time moving it transversely in steps of 007. For the spatially resolved flow of moderate velocity (peaking at -70 km s-1), we have found systematic differences in the radial velocities of lines from opposing slit positions, i.e., on alternate sides of the jet axis. The results, obtained using two independent techniques, are corrected for the spurious wavelength shift due to the uneven illumination of the STIS slit. Other instrumental effects are shown to be either absent or unimportant. The derived relative Doppler shifts range from 5 to 20 km s-1. Assuming that the flow is axially symmetric, the velocity shifts are consistent with the southeastern side of the flow moving toward the observer faster than the corresponding northwestern side. If this finding is interpreted as rotation, the flow is then rotating clockwise looking from the jet toward the source and the derived toroidal velocities are in the range 6-15 km s-1, depending on position. Combining these values with recent estimates of the mass-loss rate, one would obtain an angular momentum flux, for the low- to moderate-velocity regime of the flow, of w,lm ~ 3.8 × 10-5 M☉ yr-1 AU km s-1. Our findings may constitute the first detection of rotation in the initial channel of a jet flow. The derived values appear to be consistent with the predictions of popular magnetocentrifugal jet-launching models, although we cannot exclude the possibility that the observed velocity differences are due to some transverse outflow asymmetry other than rotation.

In this paper a comprehensive analysis of VLT / X-Shooter observations of two jet systems, namely ESO-H$\alpha$ 574 a K8 classical T Tauri star and Par-Lup 3-4 a very low mass (0.13~\Msun) M5 star, is presented. Both stars are known to have near-edge on accretion disks. A summary of these first X-shooter observations of jets was given in a 2011 letter. The new results outlined here include flux tables of identified emission lines, information on the morphology, kinematics and physical conditions of both jets and, updated estimates of $\dot{M}_{out}$ / $\dot{M}_{acc}$. Asymmetries in the \eso flow are investigated while the \para jet is much more symmetric. The density, temperature, and therefore origin of the gas traced by the Balmer lines are investigated from the Balmer decrements and results suggest an origin in a jet for \eso while for \para the temperature and density are consistent with an accretion flow. $\dot{M}_{acc}$ is estimated from the luminosity of various accretion tracers. For both targets, new luminosity relationships and a re-evaluation of the effect of reddening and grey extinction (due to the edge-on disks) allows for substantial improvements on previous estimates of $\dot{M}_{acc}$. It is found that log($\dot{M}_{acc}$) = -9.15 $\pm$ 0.45~\Msun yr$^{-1}$ and -9.30 $\pm$ 0.27~\Msun yr$^{-1}$ for \eso and \para respectively. Additionally, the physical conditions in the jets (electron density, electron temperature, and ionisation) are probed using various line ratios and compared with previous determinations from iron lines. The results are combined with the luminosity of the [SII]$\lambda$6731 line to derive $\dot{M}_{out}$ through a calculation of the gas emissivity based on a 5-level atom model., Comment: 22 pages, 13 figures, Accepted by A&A

We have carried out a spatio-kinematic study of the outflow from the classical T Tauri star DG Tau using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). A series of seven spatially offset long-slit spectra spaced by 0.07'' were obtained along the axis of the outflow to build up a 3-D intensity-velocity ``cube'' in various forbidden emission lines (FELs) and Ha. Here we present high spatial resolution synthetic line images close to the star in distinct radial velocity intervals (from ~ +50 km/s to ~ -450 km/s in four bins, each ~ 125 km/s wide). The lowest velocity emission is also examined in finer detail (from +60 km/s to -70 km/s in five bins ~ 25 km/s wide). We have found that the highest velocity and most highly collimated component, i.e. the jet, can be traced from DG Tau to a distance D ~ 0.7''. The jet is on the axis of a pear-shaped limb-brightened bubble which extends between 0.4'' and 1.5'' from the source and which we interpret as a bow shock. Other condensations are seen close to the star indicating ongoing temporal variations in the flow. The low-velocity component of the outflow is found to be spatially wide close to the source (~ 0.2'' at D=0.2''), in contrast to the high velocity jet (width

We propose a mechanism for the optical emission observed in the beam section of stellar jets based on the stability properties of circularly polarized Alfven waves propagating in the partially ionized medium filling the jet's channel. We first derive the relevant magnetohydrodynamic equations, which include the Hall term for such a partially ionized medium, a term which give rise to dispersive effects. Quasi-equipartition of thermal and magnetic energies is assumed, and the model is developed in the one-dimensional approximation but keeping the three components of the vectorial fields. Mild compressions or very weak shocks occur in the flow when instabilities develop, depending on the relative sign of the angular momentum of the underlying accretion disk and the external magnetic field. Simulations performed under quite general conditions show that the temperature/density perturbations associated with the instability are consistent with the average luminosity contrast observed in the jet's beam between bright knots and interknot regions.

In West Brae field, 4D seismic was used to identify late stage development targets. In the Flugga reservoir, the 4D seismic imaged the water movements that occurred over a decade of production and highlighted an area to the northwest of the field that remained un-drained or inefficiently swept. Close integration between the 4D interpretation and the understanding of the reservoir dynamic behaviour yielded an infill production target in a compartment of the Flugga reservoir sitting underneath a producing well. Multiple models were generated to explain this compartmentalisation and optimise the well placement. The results of the drilling campaign proved the 4D interpretation and the reservoir dynamic mechanisms.

We present the results of the analysis of LR optical-NIR spectra (0.6-2.4 um) of a sample 47 YSOs in the ChaI and II star-forming clouds. These data are part of the POISSON project (Protostellar Optical-Infrared Spectral Survey on NTT). The aim is to determine the accretion luminosity (Lacc) and mass accretion rate (Macc) of the sources through the analysis of the detected emission features. We also aim at verifying the reliability and consistency of the existing empirical relationships connecting emission line luminosity and Lacc. We employ five tracers (OI-6300A, Ha, CaII-8542A, Pab, and Brg) to derive the accretion luminosity. The tracers provide Lacc values showing different scatters when plotted as a function of L*. The Brg seems to be the most reliable, because it gives the minimum Lacc dispersion over the entire range of L*, whereas the other tracers provide much more scattered Lacc values, which are not expected for our homogeneous sample. The comparison between Lacc(Brg) and Lacc obtained from the other tracers also shows systematic differences among the empirical relationships. These may probably be ascribed to different excitation mechanisms contributing to the line emission, which may vary between our sample and those where the relationships were calibrated. Adopting the Lacc derived from Brg, we find Lacc=0.1L*-1L* for all sources, and Macc of the order of 10^-7-10^-9 Msun/yr. The Macc derived in ChaI are proportional to M*^2, as found in other low-mass star-forming regions. The discrepancies observed in the case of Lacc(Brg) and Lacc(Pab) can be related to different intrinsic Pab/Brg, ratios. The derived ratios show the existence of two different emission modalities, one that agrees with predictions of both wind and accretion models, the other suggesting optically thick emission from relatively small regions (10^21-10^22 cm^-3) with gas at low temperatures (, 22 pages, 8 figures, accepted for publication in A&A; institute affiliations and typos corrected

It is now apparent that classical T Tauri-like outflows commonly accompany the formation of young brown dwarfs. To date two optical outflows have been discovered and results presented in this paper increase this number to three. Using spectro-astrometry the origin of the LS-RCrA 1 forbidden emission lines in a blue-shifted outflow is confirmed. The non-detection of the red-shifted component of the outflow in forbidden lines, along with evidence for some separation between low and high velocity outflow components, do not support the hypothesis that LS-RCrA 1 has an edge-on accretion disk. The key result of this analysis is the discovery of an outflow component to the H-alpha line. The H-alpha line profile has blue and red-shifted features in the wings which spectro-astrometry reveals to also originate in the outflow. The discovery that H-alpha emission in BDs can have a significant contribution from an outflow suggests the use of H-alpha line widths as a proxy of mass accretion in BDs is not clear-cut. This method assumes that any contribution to the H-alpha line flux from a possible outflow is negligible. Finally the fact that the H-alpha line traces both lobes of the outflow while only the blue-shifted lobe is seen in forbidden emission points to the presence of a dust hole in the accretion disk of LS-RCrA 1. This is commonly seen in CTTSs and is assumed to signal the onset of planet formation., Comment: 13 pages, 2 figures

A well-collimated bipolar jet emanating from the classic T Tauri star RW Aur A (HH 229) has been traced out to 15″ in the redshifted [2] and over 100″ in the blueshifted lobe [3]. Long-slit spectra of the RW Aur jet were taken on 10. Dec. 2000 with the STIS spectrograph on board the HST. The spectrographslit of width 0″:1 and length 10″ was moved across the jet in seven positions from NW to SE, keeping it parallel to the jet axis. As a result, seven spectra covering the jet in both dimensions were obtained. The observations taken with the G750M grating cover the three prominent forbidden emission doublets – [O I] (λλ 6300,6363, [N II] λλ 6548,6583, and [S II] λλ 6716,6731. The current study presents a continuation of the analysis of the HST/STIS spectroscopy of the RW Aur jet started in Woitas et al. [5]. For extraction of the physical quantities we followed the well-established method described in Bacciotti and Eisloffel [1].

Here we discuss our work to date on the topic of outflows driven by young brown dwarfs. Soon after the discovery of large numbers of young brown dwarfs in star forming regions it became apparent that many of these sub‐stellar objects were accreting and had accretion disks, analogous to the T Tauri stars. As outflow activity in low mass protostars is strongly connected to accretion it was reasonable to expect these accreting brown dwarfs to also be driving outflows. In the last three years we have searched for brown dwarf outflows using high quality optical spectra obtained with UVES on the VLT and the technique of spectro‐astrometry. To date we have uncovered 5 brown dwarf outflows. Here we discuss our method and outline our results to date. The long‐term aim of this work is to make a comprehensive comparison between proto‐stellar outflows and those driven by sub‐stellar mass objects.

In this pilot study, we examine molecular jets from the embedded Class I sources, HH 26 and HH 72, to search, for the first time, for kinematic signatures of jet rotation from young embedded sources.High resolution long-slit spectroscopy of the H2 1-0 S(1) transition was obtained using VLT/ISAAC, position-velocity (PV) diagrams constructed and intensity-weighted radial velocities transverse to the jet flow measured. Mean intensity-weighted velocities vary between vLSR ~ -90 and -65 km/s for HH 26, and -60 and -10 km/s for HH 72; maxima occur close to the intensity peak and decrease toward the jet borders. Velocity dispersions are ~ 45 and ~ 80 km/s for HH 26 and HH 72, respectively, with gas motions as fast as -100 km/s present. Asymmetric PV diagrams are seen for both objects which a simple empirical model of a cylindrical jet section shows could in principle be reproduced by jet rotation alone. Assuming magneto-centrifugal launching, the observed HH 26 flow may originate at a disk radius of 2-4 AU from the star with the toroidal component of the magnetic field dominant at the observed location, in agreement with magnetic collimation models. We estimate that the kinetic angular momentum transported by the HH 26 jet is ~ 2E5 M_sun/yr AU km/s. This value (a lower limit to the total angular momentum transported by the flow) already amounts to 70% of the angular momentum that has to be extracted from the disk for the accretion to proceed at the observed rate. The results of this pilot study suggest that jet rotation may also be present at early evolutionary phases and supports the hypothesis that they carry away excess angular momentum, thus allowing the central protostar to increase its mass., 11 pages, 5 figures, accepted for publication in Astronomy & Astrophysics

We present VLT-ISAAC medium resolution spectroscopy of the HH34 and HH1 jets. Our aim is to derive the kinematics and the physical parameters and to study how they vary with jet velocity. We use several important diagnostic lines such as [FeII] 1.644um, 1.600um and H2 2.122um. In the inner jet region of HH34 we find that both the atomic and molecular gas present two components at high and low velocity. The [FeII] LVC in HH34 is detected up to large distances from the source (>1000 AU), at variance with TTauri jets. In H2 2.122um, the LVC and HVC are spatially separated. We detect, for the first time, the fainter red-shifted counterpart down to the central source. In HH1, we trace the jet down to ~1" from the VLA1 driving source: the kinematics of this inner region is again characterised by the presence of two velocity components, one blue-shifted and one red-shifted with respect to the source LSR velocity. In the inner HH34 jet region, ne increases with decreasing velocity. Up to ~10" from the driving source, and along the whole HH1 jet an opposite behaviour is observed instead, with ne increasing with velocity. In both jets the mass flux is carried mainly by the high-velocity gas. A comparison between the position velocity diagrams and derived electron densities with models for MHD jet launching mechanisms has been performed for HH34. While the kinematical characteristics of the line emission at the jet base can be, at least qualitatively, reproduced by both X-winds and disc-wind models, none of these models can explain the extent of the LVC and the dependence of electron density with velocity that we observe. It is possible that the LVC in HH34 represents gas not directly ejected in the jet but instead denser ambient gas entrained by the high velocity collimated jet., A&A accepted

In present days, high angular resolution is making the difference in our understanding of Herbig—Haro jets associated with forming stars. To support this statement, we illustrate very recent analyses of Hubble Space Telescope 0.″1 angular resolution data. For one object (the optical flow from DG Tau) 2D velocity channel maps at the base of the flow show for the first time that the jet is denser, more excited and more collimated as the velocity gets higher, in an overall onion-like structure. We also have tentative evidence for rotation in the same region. These results appear to confirm magneto-hydrodynamic (MHD) acceleration models. The excitation properties, however, still need to find a satisfactory description. We discuss how using VLT and VLTI we can further shed light on the aspects of the picture that are still unclear.

We present a non-standard, straightforward procedure for a model-independent determination of crucial physical parameters of the linear section of stellar jets, such as the hydrogen ionization fraction x and the temperature T e of the emitting gas. The method can be easily applied to every Herbig-Haro jet for which the brightest red lines have been measured, even if the lines are not calibrated and the ratios are not corrected for reddening. In the cases of HH 34 and HH 111 we find x∼0.1 and T e∼6000. The momentum rates evaluated with the derived total number densities (N∼104 cm−3) give strong support to the picture in which the luminous jet is only the fastest and most ionized component of a wider neutral flow that, in turn, has the capability of accelerating a molecular outflow. The ionization fraction cannot be explained in terms of equilibrium processes reflecting the local physical conditions of the medium, however the recombination length scales turn out to be comparable to the linear extension of the most luminous part of the jets: the observed degree of ionization is most likely the remnant of the heating and the excitation occurred in the initial accelerating region. This picture is supported by our diagnostics of RW Aur’s optical jet, for which spatially resolved spectra have been taken: in this case the ionization fraction (around 10% again) is found to decrease slowly with distance from the star.

A new set of exact analytical solutions of the axisymmetric Magneto Hydro-Dynamic equations for stationary and incompressible flows is presented. The proposed method of solution allows to find simply the explicit analytic expressions of the magnetic and flow surfaces. The most relevant solution can be thought of as a plasma flow within a channel of variable width, whose radius oscillates periodically between two limiting values fixed by the total pressure. As periodicity is retained in all physical quantities, the model could give explanation to the “knotty” structure observed in the jet phenomenon.

An enigmatic, small class of IR and X-ray luminous sources, named ``Composite'' starburst/Seyfert galaxies, has been defined from IRAS and RASS data. The objects have optical spectra dominated by the features of HII galaxies (plus, in some cases, weak Seyfert signatures) but X-ray luminosities higher than expected from starbursts and more typical of Seyfert nuclei. The true nature of this class of objects is still unknown. We present Chandra data of four of these galaxies that were obtained to investigate the nature of the X-ray source. The X-ray spectrum, the lack of any significant extended component, and the observed variability indicate that the AGN is the dominant component in the X-ray domain., Comment: 4 pages; 3 figure; proceedings of XLVIII Congresso della Societa' Astronomica Italiana, Milano, Italy 19-23 april 2004, to be published on MemSAIt; Eds. A. Wolter; G. Israel; F. Bacciotti