Search

Absorption features in stellar atmospheres are often used to calibrate photocentric velocities for kinematic analysis of further spectral lines. The Li feature at $\sim$ 6708 {\AA} is commonly used, especially in the case of young stellar objects for which it is one of the strongest absorption lines. However, this is a complex line comprising two isotope fine-structure doublets. We empirically measure the wavelength of this Li feature in a sample of young stars from the PENELLOPE/VLT programme (using X-Shooter, UVES and ESPRESSO data) as well as HARPS data. For 51 targets, we fit 314 individual spectra using the STAR-MELT package, resulting in 241 accurately fitted Li features, given the automated goodness-of-fit threshold. We find the mean air wavelength to be 6707.856 {\AA}, with a standard error of 0.002 {\AA} (0.09 km/s) and a weighted standard deviation of 0.026 {\AA} (1.16 km/s). The observed spread in measured positions spans 0.145 {\AA}, or 6.5 km/s, which is up to a factor of six higher than typically reported velocity errors for high-resolution studies. We also find a correlation between the effective temperature of the star and the wavelength of the central absorption. We discuss how exclusively using this Li feature as a reference for photocentric velocity in young stars could potentially be introducing a systematic positive offset in wavelength to measurements of further spectral lines. If outflow tracing forbidden lines, such as [O i] 6300 {\AA}, are actually more blueshifted than previously thought, this then favours a disk wind as the origin for such emission in young stars., Comment: Accepted for publication in A&A

Among all the detection of exoplanets, the esistence of giant planets on wide orbits (r > 100 au) is of major importance to test the planet formation mechanism. At such distance from the star, grain growth is inhibited primarily by the low dust density. Gravitational instability might be at work in (some) disks. And yet, according to the measurements of the total gas mass, disks do not appear to be gravitationally unstables. The occurence of such 'cold Jupiters' remains a puzzle. Interestingly, the recent ALMA high angular resolution campaigns do show the presence of dust gaps and rings in protoplanetary disks on wide orbits, on spatial scales similar to those of cold Jupiters. In this regard, HD 100546 is a remarkable system. The protoplanetary system HD 100546: HD 100546 is a 2.5 solar mass star surrounded by a large disk extending out to nearly 500 au. The disk show spiral arms at different spatial scales, an inner dust cavity of nearly 28 au radius, a wide dust gap between nearly 50 and 150 au and a faint and eccentric outer ring centered at 200 au. Figure 1 shows the distribution of the millimeter continuum as seen by ALMA. The peculiar disk structures can be explained with the presence of two giant protoplanets (orbiting at at nearly 15 au and 100 au) interacting with the surrounding gas and dust. Notably, HD 100546 is one of the only disk in which cold water emission has been detected. I will present some recent ALMA results along with hydrodynamical simulations and a new analysis of the water distribution in the disk.

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made., The goal of the Ariel space mission is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. The planetary bulk and atmospheric compositions bear the marks of the way the planets formed: Ariel’s observations will therefore provide an unprecedented wealth of data to advance our understanding of planet formation in our Galaxy. A number of environmental and evolutionary factors, however, can affect the final atmospheric composition. Here we provide a concise overview of which factors and effects of the star and planet formation processes can shape the atmospheric compositions that will be observed by Ariel, and highlight how Ariel’s characteristics make this mission optimally suited to address this very complex problem. © The Author(s) 2021., D.T., S.F., S.M., E.S., and A.N. acknowledge the support of the Italian Space Agency (ASI) through the ASI-INAF contract 2018-22-HH.0. D.T., C.C., D.F., and L.P. acknowledge the support of the PRIN-INAF 2016 “The Cradle of Life - GENESIS-SKA (General Conditions in Early Planetary Systems for the rise of life with SKA”. D.T., S.F., S.M. D.F, J.M., F.O., P.W. acknowledge the support of the Italian National Institute of Astrophysics (INAF) through the INAF Main Stream project “Ariel and the astrochemical link between circumstellar discs and planets” (CUP: C54I19000700005). S.M. acknowledges support from the European Research Council via the Horizon 2020 Framework Programme ERC Synergy “ECOGAL” Project GA-855130. M.K. acknowledges funding by the University of Tartu ASTRA project 2014-2020.4.01.16-0029 KOMEET “Benefits for Estonian Society from Space Research and Application”, financed by the EU European Regional Development Fund. J.M.D.K. gratefully acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through an Emmy Noether Research Group (grant number KR4801/1-1) and the DFG Sachbeihilfe (grant number KR4801/2-1), as well as from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme via the ERC Starting Grant MUSTANG (grant agreement number 714907). The research of O.P. is funded by the Royal Society, through Royal Society Dorothy Hodgkin Fellowship DH140243. M.P. thanks the support to NuGrid from STFC (through the University of Hull’s Consolidated Grant ST/R000840/1), and access to VIPER, the University of Hull High Performance Computing Facility. M.P. acknowledges the support from the ”Lendulet-2014” Program of the Hungarian Academy of Sciences (Hungary), from the ERC Consolidator Grant (Hungary) funding scheme (Project RADIOSTAR, G.A. n. 724560), by the National Science Foundation (NSF, USA) under grant No. PHY-1430152 (JINA Center for the Evolution of the Elements). M.P. also thanks the UK network BRIDGCE and the ChETEC COST Action (CA16117), supported by COST (European Cooperation in Science and Technology). M.I. thanks the support by JSPS KAKENHI 18H05439. C.D. acknowledges financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709), and the Group project Ref. PID2019-110689RB-I00/AEI/10.13039/501100011033.

Imai et al., The chemical diversity of low-mass protostellar sources has so far been recognized, and environmental effects are invoked as its origin. In this context, observations of isolated protostellar sources without the influence of nearby objects are of particular importance. Here, we report the chemical and physical structures of the low-mass Class 0 protostellar source IRAS 16544−1604 in the Bok globule CB 68, based on 1.3 mm Atacama Large Millimeter/submillimeter Array observations at a spatial resolution of ∼70 au that were conducted as part of the large program FAUST. Three interstellar saturated complex organic molecules (iCOMs), CH3OH, HCOOCH3, and CH3OCH3, are detected toward the protostar. The rotation temperature and the emitting region size for CH3OH are derived to be 131 ± 11 K and ∼10 au, respectively. The detection of iCOMs in close proximity to the protostar indicates that CB 68 harbors a hot corino. The kinematic structure of the C18O, CH3OH, and OCS lines is explained by an infalling–rotating envelope model, and the protostellar mass and the radius of the centrifugal barrier are estimated to be 0.08–0.30 M⊙ and, This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.01376.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The authors acknowledge financial support from JSPS and MAEE under the Japan–France Integrated Action Program (SAKURA: 25765VC). D.J. is supported by NRC Canada and by an NSERC Discovery Grant. E.B. and G.B. acknowledge funding from the European Research Council under the European Union's Horizon 2020 research and innovation program, for the project "The Dawn of Organic Chemistry," grant agreement No. 741002. G.B. acknowledges support from the PID2020-117710GB-I00 grant funded by MCIN/AEI/10.13039/501100011033 and from the Unit of Excellence María de Maeztu 2020–2023 award to the Institute of Cosmos Sciences (CEX2019-00918-M). I.J.-S. has received partial support from the Spanish State Research Agency (AEI) through project Nos. PID2019-105552RB-C41 and MDM-2017-0737 Unidad de Excelencia "Maria de Maeztu" - Centro de Astrobiologia (CSIC-INTA). This study is supported by grants-in-aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (18H05222, 18J11010, 19H05069, 19K14753, and 21K13954).

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution., Comment: Ariel Definition Study Report, 147 pages. Reviewed by ESA Science Advisory Structure in November 2020. Original document available at: https://www.cosmos.esa.int/documents/1783156/3267291/Ariel_RedBook_Nov2020.pdf/

Introduction: Millimeter and centimeter observations are discovering an increasing number of interstellar complex organic molecules (iCOMs) in a large variety of star-forming sites from the earliest stages of star formation to protoplanetary disks. To correctly interpret the distribution and abundances of iCOMs observed along the formation process of a Sun-like star (i.e. in pre-stellar dense cores1,2, hot corinos around protostars3,4, in the associated jets and outflows5,6, and protoplanetary disks7), we need to first comprehend their formation processes and the mechanism responsible for their release in gas-phase. In this context, it is pivotal to understand the influence of the solid phase interactions between iCOMs and grain surface in the thermal desorption process and the subsequent presence of molecular species in the gas phase. Thermal desorption can be characterized through laboratory experiments using interstellar ice analogs deposited on grains similar to interstellar ones deriving important parameters such as the desorption temperatures and energies. Up to now, temperature-programmed desorption (TPD) experiments have been carried out mainly from graphite and amorphous water ice surfaces8,9,10,11. As far as we know, TPD experiments from grain surfaces are lacking in the literature, although mineral matrices can selectively adsorb, protect, and allow the iCOMs concentration on their surface. Molecules can diffuse inside the grains and so, the presence of grains can influence the desorption and release of the iCOMs in the gas phase. Laboratory measurements: We report our new recently published laboratory results12 on TPD experiments of astrophysical relevant ice mixtures of water, acetonitrile (CH3CN), and acetaldehyde (CH3COH) from micrometric grains of silicate olivine ((Mg,Fe)2SiO4) used as interstellar dust analog on which the icy mixtures were condensed at 17 K inside the ultra-high vacuum (UHV) chamber (P~6.68 × 10-10 mbar). The ice mixtures condensed on olivine dust were heated at a constant rate, so the molecules diffused and desorbed from the dusty sample, and in situ TPD analysis was made. Results: We found that in the presence of grains, only a fraction of acetaldehyde and acetonitrile desorbs at about 100 K and 120 K respectively, while 40% of the molecules are retained by fluffy grains of the order of 100 μm up to temperatures of 200 K. In contrast with the typical assumption that all molecules are desorbed in regions with temperatures higher than 100 K, this result implies that about 40% of the molecules can survive on the grains enabling the delivery of volatiles towards regions with temperatures as high as 200 K. This may be important in protoplanetary disks where the submicrometric interstellar grains begin to agglomerate into fluffy grains of hundreds of microns. The diffusion of molecules on the silicate surface is a valuable process enabling the permanence of the ices in the inner part of the disk. This implies that O-rich and N-rich volatiles ice can survive up to ∼ 200 K, broadening the snowlines of O- and N-bearing molecules, such as CH3CN and CH3COH. The presence of dust grains in the protoplanetary disk can therefore determine the approach of the snowlines towards the star and allow the presence of water and volatile species in Earth-like planets forming region. These studies offer a necessary support to interpret observational data and may help our understanding of iCOMs formation providing an estimate of the fraction of molecules released at various temperatures. G. A. Blake, E. C. Sutton, C.R. Masson, T.G. Phillips, ApJ. 1987, 315 E. Herbst & E. F. van Dishoeck, ARA&A. 2009, 47 S. Cazaux, A. G. G. M. Tielens, C. Ceccarelli et al., ApJ. 2003, 593 C. Ceccarelli, P. Caselli, E. Herbst, A. G. G. M. Tielens & E. Caux, Protostars and Planets V. 2007, 47 R. Bachiller, & M. Pérez Gutiérrez, ApJ. 1997, 48 C. Codella, B. Lefloch, C. Ceccarelli et al., A&A. 2010, 518 J. Lee, S. Lee, G. Baek et al., Nature Astronomy. 2019, 3 M. P. Collings, M. A. Anderson, R. Chen et al., MNRAS. 2004, 354 T. Hama, N. Watanabe, A. Kouchi & M. Yokoyama, ApJL. 2011, 738 J. Shi, G. A. Grieves & T. M. Orlando, ApJ. 2015, 804 H. Chaabouni, S. Diana, T. Nguyen & F. Dulieu, A&A. 2018, 612 M. A. Corazzi, J. R. Brucato, G. Poggiali, L. Podio, D. Fedele & C. Codella, accepted on ApJ. 2021

The evolution of young stars and disks is driven by the interplay of several processes, notably accretion and ejection of material. Critical to correctly describe the conditions of planet formation, these processes are best probed spectroscopically. About five-hundred orbits of the Hubble Space Telescope (HST) are being devoted in 2020-2022 to the ULLYSES public survey of about 70 low-mass (M, Comment: Accepted for publication on Astronomy & Astrophysics. 15 pages + appendix, language edited version

Millimeter and centimeter observations are discovering an increasing number of interstellar complex organic molecules (iCOMs) in a large variety of star forming sites, from the earliest stages of star formation to protoplanetary disks and in comets. In this context it is pivotal to understand how the solid phase interactions between iCOMs and grain surfaces influence the thermal desorption process and, therefore, the presence of molecular species in the gas phase. In laboratory, it is possible to simulate the thermal desorption process deriving important parameters such as the desorption temperatures and energies. We report new laboratory results on temperature-programmed desorption (TPD) from olivine dust of astrophysical relevant ice mixtures of water, acetonitrile, and acetaldehyde. We found that in the presence of grains, only a fraction of acetaldehyde and acetonitrile desorbs at about 100 K and 120 K respectively, while 40% of the molecules are retained by fluffy grains of the order of 100 {\mu}m up to temperatures of 190-210 K. In contrast with the typical assumption that all molecules are desorbed in regions with temperatures higher than 100 K, this result implies that about 40% of the molecules can survive on the grains enabling the delivery of volatiles towards regions with temperatures as high as 200 K and shifting inwards the position of the snowlines in protoplanetary disks. These studies offer a necessary support to interpret observational data and may help our understanding of iCOMs formation providing an estimate of the fraction of molecules released at various temperatures., Comment: Accepted for Publication on Astrophysical Journal

Mid-infrared imaging traces the sub-micron and micron sized dust grains in protoplanetary disks and it offers constraints on the geometrical properties of the disks and potential companions, particularly if those companions have circumplanetary disks. We use the VISIR instrument and its upgrade NEAR on the VLT to take new mid-infrared images of five (pre-)transition disks and one circumstellar disk with proposed planets and obtain the deepest resolved mid-infrared observations to date in order to put new constraints on the sizes of the emitting regions of the disks and the presence of possible companions. We derotate and stack the data to find the disk properties. Where available we compare the data to ProDiMo (Protoplanetary Disk Model) radiation thermo-chemical models to achieve a deeper understanding of the underlying physical processes within the disks. We apply the circularised PSF subtraction method to find upper limits on the fluxes of possible companions and model companions with circumplanetary disks. We resolve three of the six disks and calculate position angles, inclinations and (upper limits to) sizes of emission regions in the disks, improving upper limits on two of the unresolved disks. In all cases the majority of the mid-IR emission comes from small inner disks or the hot inner rims of outer disks. We refine the existing ProDiMo HD 100546 model SED fit in the mid-IR by increasing the PAH abundance relative to the ISM, adopting coronene as the representative PAH, and increase the outer cavity radius to 22.3 AU. We produce flux estimates for putative planetary-mass companions and circumplanetary disks, ruling out the presence of planetary-mass companions with $L > 0.0028 L_{\odot}$ for $a > 180$ AU in the HD 100546 system. Upper limits of 0.5 mJy-30 mJy are obtained at 8 $��$m-12 $��$m for potential companions in the different disks., Accepted in A&A

The composition of giant planets is imprinted by their migration history and the compositional structure of their hosting disks. Studies in recent literature investigate how the abundances of C and O can constrain the formation pathways of giant planets forming within few tens of au from the star. New ALMA observations, however, suggest planet-forming regions possibly extending to hundreds of au. We explore the implications of these wider formation environments through n-body simulations of growing and migrating giant planets embedded in planetesimal disks, coupled with a compositional model of the protoplanetary disk where volatiles are inherited from the molecular cloud and refractories are calibrated against extrasolar and Solar System data. We find that the C/O ratio provides limited insight on the formation pathways of giant planets that undergo large-scale migration. This limitation can be overcome thanks to nitrogen and sulphur. Jointly using the C/N, N/O and C/O ratios breaks any degeneracy in the formation and migration tracks of giant planets. The use of elemental ratios normalized to the respective stellar ratios supplies additional information on the nature of giant planets, thanks to the relative volatility of O, C and N in disks. When the planetary metallicity is dominated by the accretion of solids C/N* $>$ C/O* $>$ N/O* (* denoting this normalized scale), otherwise N/O* $>$ C/O* $>$ C/N*. The S/N ratio provides an additional independent probe into the metallicity of giant planets and their accretion of solids., 27 pages, 10 figures and 7 tables. Accepted version of the article published on The Astrophysical Journal (includes 1 extra figure and additional text with respect to previous preprint)

Context. The mass accretion rate (Ṁacc) is the fundamental parameter to understand the process of mass assembly that results in the formation of a low-mass star. This parameter has been largely studied in Classical T Tauri stars in star-forming regions with ages of ∼1 − 10 Myr. However, little is known about the accretion properties of young stellar objects (YSOs) in younger regions and early stages of star formation, such as in the Class 0/I phases. Aims. We present new near-infrared spectra of 17 Class I/Flat and 35 Class II sources located in the young (< 1 Myr) NGC 1333 cluster, acquired with the KMOS instrument at the Very Large Telescope. Our goal is to study whether the mass accretion rate evolves with age, as suggested by the widely adopted viscous evolution model, by comparing the properties of the NGC 1333 members with samples of older regions. Methods. For the Class II sources in our sample, we measured the stellar parameters (SpT, AV, and L⋆) through a comparison of the IR spectra with a grid of non-accreting Class III stellar templates. We then computed the accretion luminosity by using the known correlation between Lacc and the luminosity of HI lines (Paβ and Brγ). For the Class I sample, where the presence of a large IR excess makes it impossible to use the same spectral typing method, we applied a procedure that allowed us to measure the stellar and accretion luminosity in a self-consistent way. Mass accretion rates Ṁacc were then measured once masses and radii were estimated adopting suitable evolutionary tracks. Results. The NGC 1333 Class II sources of our sample have Lacc ∼ 10−4 − 1 L⊙ and Ṁacc ∼ 10−11 − 10−7 M⊙ yr−1. We find a correlation between accretion and stellar luminosity in the form of log Lacc = (1.5 ± 0.2)log L⋆ + ( − 1.0 ± 0.1), and a correlation between the mass accretion rate and stellar mass in the form of log Ṁacc = (2.6 ± 0.9) log M⋆ + (−7.3 ± 0.7). Both correlations are compatible within the errors with the older Lupus star-forming region, while only the latter is consistent with results from Chamaeleon I. The Class I sample shows larger accretion luminosities (∼10−2 − 102 L⊙) and mass accretion rates (∼10−9 − 10−6 M⊙ yr−1) with respect to the Class II stars of the same cloud. However, the derived mass accretion rates are not sufficiently high to build up the inferred stellar masses, assuming steady accretion during the Class I lifetime. This suggests that the sources are not in their main accretion phase and that most of their mass has already been accumulated during a previous stage and/or that the accretion is an episodic phenomenon. We show that some of the targets originally classified as Class I through Spitzer photometry are in fact evolved or low accreting objects. This evidence can have implications for the estimated protostellar phase lifetimes. Conclusions. The accretion rates of our sample are larger in more embedded and early stage YSOs. Further observations of larger samples in young star-forming regions are needed to determine if this is a general result. In addition, we highlight the importance of spectroscopic surveys of YSOs to confirm their classification and perform a more correct estimate of their lifetime.

We have observed the very low-mass Class 0 protostar IRAS 15398−3359 at scales ranging from 50 to 1800 au, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST. We uncover a linear feature, visible in H2CO, SO, and C18O line emission, which extends from the source in a direction almost perpendicular to the known active outflow. Molecular line emission from H2CO, SO, SiO, and CH3OH further reveals an arc-like structure connected to the outer end of the linear feature and separated from the protostar, IRAS 15398−3359, by 1200 au. The arc-like structure is blueshifted with respect to the systemic velocity. A velocity gradient of 1.2 km s−1 over 1200 au along the linear feature seen in the H2CO emission connects the protostar and the arc-like structure kinematically. SO, SiO, and CH3OH are known to trace shocks, and we interpret the arc-like structure as a relic shock region produced by an outflow previously launched by IRAS 15398−3359. The velocity gradient along the linear structure can be explained as relic outflow motion. The origins of the newly observed arc-like structure and extended linear feature are discussed in relation to turbulent motions within the protostellar core and episodic accretion events during the earliest stage of protostellar evolution. The authors thank the anonymous reviewer for invaluable comments. They are also grateful to Hauyu Baobab Liu for useful discussions. This paper makes use of the following ALMA data set: ADS/JAO.ALMA#2018.1.01205.L (PI: Satoshi Yamamoto). ALMA is a partnership of the ESO (representing its member states), the NSF (USA) and NINS (Japan), together with the NRC (Canada) and the NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, the AUI/NRAO, and the NAOJ. The authors thank to the ALMA staff for their excellent support. This work is supported by the projects PRIN-INAF-MAIN-STREAM 2017 Protoplanetary disks seen through the eyes of new-generation instruments, ARIEL and the astrochemical link between circumstellar disks and planets, and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programmes: The Dawn of Organic Chemistry (DOC), grant agreement No. 741002, and Astro-Chemistry Origins (ACO), grant No. 811312. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. I.J.-S. has received partial support from the Spanish FEDER (project number ESP2017-86582-C4-1-R) and the State Research Agency (AEI; project number PID2019-105552RB-C41). D.J. is supported by NRC Canada and by an NSERC Discovery Grant. This project is also supported by a Grant-in-Aid from Japan Society for the Promotion of Science (KAKENHI: Nos. 18H05222, 19H05069, 19K14753). Yuki Okoda thanks the Advanced Leading Graduate Course for Photon Science (ALPS) and Japan Society for the Promotion of Science (JSPS) for financial support. Peerreview

Planets form in protoplanetary disks and inherit their chemical composition. It is therefore crucial to understand the disks molecular content. We aim to characterize the distribution and abundance of molecules in the disk of DG Tau. In the context of the ALMA chemical survey of Disk-Outflow sources in Taurus (ALMA-DOT) we analyse ALMA observations of the disk of DG Tau in H2CO 3(1,2)-2(1,1), CS 5-4, and CN 2-1 at ~0.15", i.e. ~18 au at 121 pc. H2CO and CS originate from a disk ring at the edge of the 1.3mm dust continuum, with CS probing an outer disk region with respect to H2CO (peaking at ~70 and ~60 au, respectively). CN originates from an outermost disk/envelope region peaking at ~80 au. H2CO is dominated by disk emission, while CS probes also two streams of material possibly accreting onto the disk with a peak of emission where the stream connects to the disk. The ring- and disk-height- averaged column densities are ~2.4-8.6e13 cm-2 (H2CO), ~1.7-2.5e13 cm-2 (CS), and ~1.9-4.7e13 cm-2 (CN). Unsharp masking reveals a ring of enhanced dust emission at ~40 au, i.e. just outside the CO snowline (~30 au). CS and H2CO emissions are co-spatial suggesting that they are chemically linked. The observed rings of molecular emission at the edge of the 1.3mm continuum may be due to dust opacity effects and/or continnum over-subtraction in the inner disk; as well as to increased UV penetration and/or temperature inversion at the edge of the mm-dust which would cause an enhanced gas-phase formation and desorption of these molecules. Moreover, H2CO and CS originate from outside the ring of enhanced dust emission, which also coincides with a change of the linear polarization at 0.87mm. This suggests that outside the CO snowline there could be a change of the dust properties which would reflect in the increase of the intensity (and change of polarization) of continuum, and of molecular emission., 13 pages, accepted for publication on A&A

Through laboratory analyses it is possible to study the physical and chemical processes involving prebiotic molecules, the building blocks of life. Today thanks to the advent of new generation of (sub-) millimeter and centimeter interferometers (ALMA, NOEMA, ngVLA), an increasing number of interstellar complex organic molecules (iCOMs) is observed in star forming regions, pre-stellar dense cores, hot corinos, jets and outflow ardound protostars [1, 2, 3]. Hot corinos are inner compact (100 K) regions of some protostars [4]. In these high-temperature regions, thermal desorption is the physical process responsible for the sublimation of frozen mantles into the gas phase and so for the presence of a rich chemistry [5] in the gas phase. On the other hand, iCOMs are difficult to observe in protoplanetary disks, where, for a solar-type star, the region where the temperature reaches the values for the desorption and release into the gaseous phase of water and iCOMs (water snow line) is too close to the star (≤5 au). This region is difficult to solve but a new perspective is provided by objects such as the FU Ori systems in which the young central star undergoes a sudden increase in brightness which leads to heating of the disk and quick expansion of the snow lines to large radii. This phenomenon has been observed in the protoplanetary disk around the protostar V883 Ori [6]. Thanks to the increase in temperature of the disk and the consequent thermal desorption of the molecules, five iCOMs were recently detected: methanol, acetone, acetonitrile, acetaldehyde, and methyl formate [7]. Moreover, outbursting young stars are good new targets for looking for organic complex molecules that thermally desorb from icy mantles. The interpretation of observations can benefit from laboratory activities, where it is possible to simulate the thermal desorption process and UV irradiation of complex molecules under simulated space conditions. Furthermore, laboratory studies on thermal desorption are fundamental to constrain parameters such as the thermal desorption temperature of a given molecule and its fragments, and the binding energies involved. Here we reported the results that we have recently published about temperature-programmed desorption (TPD) analysis of pure formamide (HCONH2) ice and in the presence of TiO2 dust, before and after UV irradiation. We found that pure formamide desorbed at 220 K in high vacuum regime and after UV irradiation it fragmented mainly into NH2, HCO and CH2NO. These fragments are more volatile and desorbed before formamide (~180 K) at the same desorption temperature of water. The presence of water was due to residual deposition in the high vacuum chamber. It is reasonable to think, therefore, that the sublimation of water ice was responsible for releasing more volatile species. The same phenomenon probably occurs in the space where water is the most abundant molecule. Going forward with our investigation, we reproduced the condensation, irradiation, and desorption experiments with a substrate of TiO2 dust. In presence of grains, we observed evidence for a change in desorption temperature. Formamide desorption from TiO2 dust occurred at higher temperatures, that is, around 30 K above the temperature at which desorption takes place for pure formamide. A higher desorption temperature is direct evidence of the interactions described by the Van der Waals forces that were occurring between the molecule and the grains. The molecule interacts and diffuses into the grains and this is confirmed by the values of the binding energy that we found. When formamide desorbed directly from the cold finger of the cryostat (copper chromate surface), the binding energy found was (5.9 ± 0.3)·103 K; while when it desorbed from TiO2 dust, the binding energy found was (1.35 ± 0.08)·104 K, a value two times higher [8]. Therefore, in the chemical models of sublimation, it is essential to take into account physisorption of iCOMs on grain surfaces and their diffusion to correctly describe the desorption process, that is, to constrain desorption temperatures and binding energies [8]. Furthermore, our experiments show something more than the desorption temperature and the binding energy of formamide. The molecular fragments observed in laboratory (NH2, HCO and CH2NO) can be used to indirectly measure the presence of formamide through detection of relative abundance (e.g., [NH2]/[HCO]∼4).We reported also preliminary results on laboratory studies about thermal desorption of ice mixtures of acetaldehyde and acetonitrile from crystalline olivine grains.These studies offer support to observational data and improve our understanding of the role of the grain surface in enriching the chemistry in space. References[1]Beltrán, M. T. et al. 2009, The Astrophysical Journal Letters, 690 [2] Rivilla, V. M. et al. 2017, Astronomy & Astrophysics, 598 [3] Codella, C. et al. 2015, Mon. Not. R. Astron. Soc., 449 [4]Ceccarelli, C. et al. 1999, Astronomy and Astrophysics, 342[5] López-Sepulcre, A. et al. 2015, MNRAS, 449[6] Cieza, L. A. et al. 2016, Nature, 535, Issue 7611[7] Lee, J. et al. 2019, Nature Astronomy,3, 314[8] Corazzi, M. A. et al. 2020, A&A, 636, A63

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.

New instruments such as the ALMA interferometer and SPHERE on VLT allowed to obtain a large number of high-resolution images of protoplanetary discs. In these images, substructures such as gaps and rings can be clearly resolved and appear to be very common (see eg. Andrews et al. 2018). A natural explanation for the origin of such structures is the dynamical interaction of the gas and dust in the disc with one or more planets embedded in the parental disc (e.g. Lin & Papaloizou 1979, Dipierro et al. 2015, Rosotti et al. 2017, ..). Detections of planets embedded in disks are rare (e.g. Quanz et al. 2013, Keppler et al. 2018) and are mostly related to giant planets at wide orbits. However, the observed structures can be due to the interaction between the disc and low-mass planets. Planet-disc interaction can be studied with a synergy between observational results, current theoretical model and numerical simulations. In particular, theoretical models can find “signatures” to spot the presence of planets in discs, such as dusty or gaseous features due to the presence of circumplanetary discs or accretion streams (Bae et al. 2019, Toci et al. 2020) to be compared with real observations (Isella et al. 2019). I will present an analysis of several 3D SPH numerical simulations devised to analyze planet-disc interaction in presence of two giant planets. I will then compare my results with two observed systems: (1) HD169142 (Fedele et al.2017, Perez et al. 2019), a well studied source with two prominent rings in dust and gas; (2) PDS 70, the first source where protoplanets have been directly observed (Keppler et al. 2018). We initialise the system containing two giant planets in the disc (hereafter planet b and planet c respectively), studying the initial conditions that lead to the formation of a cavity in the gas distribution and rings in the dust. I will present the results about the dynamics of these discs (gap width, ring size and shape, cavity shape) and the properties of the planets (Toci et al., ApJL 2020, Toci et al. 2020, in prep.). My results show that the presence of two giant planets in a 5:1 resonance can be responsible of a long-lived dust ring between them, while at the same time creating a large gas cavity. However, the dust ring is absent when the giant planets end up in a closer resonance (3:1 or 2:1). I will also show how important it is to consider the migration and the accretion of planets for modelling observational results. Indeed, the interaction between the planets and the disc can give signatures both in the dust and gas components, leading to detectable features. In particular, our results suggest that the spur in the observed 1.3 mm continuum images of Perez et al. 2019 can be due to the interaction between the inner giant and the inner dust ring (see Fig. 1 and Fig. 2). If so, the spur should move according to the orbital motion of the planet. This theoretical prediction will be testable in a few years with new ALMA observations. Similarly, in the case of PDS70, the structures observed in Keppler et al. 2018 and Isella et al. 2019 can be explained with an accretion stream from the disc to the planet and the presence of a dusty circumplanetary disc (see Fig. 3 and Fig. 4).

We performed a deep search for CCS, SO, SO2, OCS, H2S, H2CS and other molecules in the DM Tau protoplanetary disk at 2mm with PolyFiX@NOEMA. With a beam of ~2''x1'' and a spectral resolution of 0.3 km/s, a high sensitivity of ~3.8 mJy/beam was achieved. We detected o-H2S, o-H2CS, and DNC (first time in DM Tau) as well as H13CO+, N2D+, and, tentatively, HC3N. We have not detected SO2, our main target molecule. We used the non-LTE radiative transfer code RADEX to derive disk-averaged column densities and their upper limits. These values, together with our previous ALMA CS data were used for disk chemical modeling. The presence of CS and the lack of SO2 in the DM Tau disk molecular layer can only be reliably explained by the disk model with a non-solar gas-phase C/O ratio of ~1, supporting previous findings.

Bianchi, E. et al., The study of hot corinos in solar-like protostars has been so far mostly limited to the Class 0 phase, hampering our understanding of their origin and evolution. In addition, recent evidence suggests that planet formation starts already during Class I phase, which therefore represents a crucial step in the future planetary system chemical composition. Hence, the study of hot corinos in Class I protostars has become of paramount importance. Here, we report the discovery of a hot corino towards the prototypical Class I protostar L1551 IRS5, obtained within the ALMA (Atacama Large Millimeter/submillimeter Array) Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar-like protostars).We detected several lines from methanol and its isotopologues (13CH3OH and CH2DOH), methyl formate, and ethanol. Lines are bright towards the north component of the IRS5 binary system, and a possible second hot corino may be associated with the south component. The methanol lines' non-LTE analysis constrains the gas temperature (100 K), density (1.5 × 108 cm3), and emitting size (10 au in radius). All CH3OH and 13CH3OH lines are optically thick, preventing a reliable measure of the deuteration. The methyl formate and ethanol relative abundances are compatible with those measured in Class 0 hot corinos. Thus, based on this work, little chemical evolution from Class 0 to I hot corinos occurs., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Determining the mechanisms that drive the evolution of protoplanetary disks is a necessary step to understand how planets form. Here we measured the mass accretion rate for young stellar objects at age >5 Myr, a critical test for the current models of disk evolution. We present the analysis of the spectra of 36 targets in the ~5-10 Myr old Upper Scorpius region for which disk masses were measured with ALMA. We find that the mass accretion rates in this sample of old but still survived disks are similarly high as those of the younger (10^-9 Msun/yr while having low disk masses. Furthermore, the median values of the measured mass accretion rates in the disk mass ranges where our sample is complete at a level ~60-80% are compatible in these three regions. At the same time, the spread of mass accretion rates at any given disk mass is still >0.9 dex even at age>5 Myr. These results are in contrast with simple models of viscous evolution, which would predict that the values of the mass accretion rate diminish with time, and a tighter correlation with disk mass at age>5 Myr. Similarly, simple models of internal photoevaporation cannot reproduce the observed mass accretion rates, while external photoevaporation might explain the low disk masses and high accretion rates. A partial possible solution to the discrepancy with the viscous models is that the gas-to-dust ratio of the disks at >5 Myr is significantly different and higher than the canonical 100, as suggested by some dust and gas disk evolution models. The results shown here require the presence of several inter-playing processes, such as detailed dust evolution, external photoevaporation and possibly MHD winds, to explain the secular evolution of protoplanetary disks., Comment: Accepted on Astronomy & Astrophysics. Language edited version

During the million years of evolution, gas dust and ice in protoplanetary disks can be chemically reprocessed. There are evidences that the gas-phase carbon and oxygen abundances are sub-solar in disks belonging to nearby star forming regions. These findings have a major impact on the composition of the primary atmosphere of giant planets (but it may also be valid for super-Earths and sub-Neptunes) as they accrete their gaseous envelopes from the surrounding material in the disk. In this study, we performed a thermo-chemical modelling analysis with the aim at testing how reliable and robust are the estimates of elemental abundance ratios based on (sub-)millimeter observations of molecular lines. We created a grid of disk models for the following different elemental abundance ratios: C/O, N/O and S/O, and, we computed the line flux of a set of carbon-, nitrogen and sulphur-bearing species, namely CN, HCN, NO, C$_{2}$H, c--C$_{3}$H$_{2}$, H$_{2}$CO, HC$_{3}$N, CH$_{3}$CN, CS, SO, H$_{2}$S and H$_{2}$CS, that have been detected with present (sub-)millimeter facilities such as ALMA and NOEMA. We find that the line fluxes, once normalized to the flux of the $^{13}$CO $J=2-1$ line, are sensitive to the elemental abundance ratios. On the other hand, the stellar and disk physical parameters have only a minor effect of the line flux ratios. Our results demonstrate that a simultaneous analysis of multiple molecular transitions is a valid approach to constrain the elemental abundance ratio in protoplanetary disks., Accepted for publication to A&A

Aims. Formamide (HCONH2) is the simplest molecule containing the peptide bond first detected in the gas phase in Orion-KL and SgrB2. In recent years, it has been observed in high temperature regions such as hot corinos, where thermal desorption is responsible for the sublimation of frozen mantles into the gas phase. The interpretation of observations can benefit from information gathered in the laboratory, where it is possible to simulate the thermal desorption process and to study formamide under simulated space conditions such as UV irradiation. Methods. Here, two laboratory analyses are reported: we studied formamide photo-stability under UV irradiation when it is adsorbed by space relevant minerals at 63 K and in the vacuum regime. We also investigated temperature programmed desorption of pure formamide ice in the presence of TiO2 dust before and after UV irradiation. Results. Through these analyses, the effects of UV degradation and the interaction between formamide and different minerals are compared.We find that silicates, both hydrates and anhydrates, offer molecules a higher level of protection from UV degradation than mineral oxides. The desorption temperature found for pure formamide is 220 K. The desorption temperature increases to 250 K when the formamide desorbs from the surface of TiO2 grains. Conclusions. Through the experiments outlined here, it is possible to follow the desorption of formamide and its fragments, simulate the desorption process in star forming regions and hot corinos, and constrain parameters such as the thermal desorption temperature of formamide and its fragments and the binding energies involved. Our results offer support to observational data and improve our understanding of the role of the grain surface in enriching the chemistry in space., Comment: In press Astronomy and Astrophysics, 13 pages, 12 figures

We report on the discovery of periodic dips in the multiband lightcurve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one among the peculiar objects that display very low or negligible accretion both in their UV continuum and spectral lines, although they present a remarkable infrared excess emission characteristic of optically-thick circumstellar disks. We have analyzed a VLT/X-Shooter spectrum with the tool ROTFIT to determine the stellar parameters. The latter, along with photometry from our campaign with the REM telescope and from the literature, have allowed us to model the spectral energy distribution and to estimate the size and temperature of the inner and outer disk. From the rotational period of the star/disk system of 3.45 days we estimate a disk inclination of 36$^\circ$. The depth of the dips in different bands has been used to gain information about the occulting material. A single extinction law is not able to fit the observed behavior, while a two-component model of a disk warp composed of a dense region with a gray extinction and an upper layer with an ISM-type extinction provides a better fit of the data., 11 pages, 11 figures; accepted for publication in Astronomy & Astrophysics

The chemical composition of planets is inherited by the distribution of the various molecular species in the protoplanetary disk at thetime of their formation. As of today, only a handful of disks has been imaged in multiple spectral lines with high spatial resolution. As part of a small campaign devoted to the chemical characterization of disk-outflow sources in Taurus, we report on new ALMA Band 6 observations with 20 au resolution toward the embedded young star DG Tau B. Images of the continuum emission reveals a dust disk with rings and, putatively, a leading spiral arm. The disk, as well as the prominent outflow cavities, are detected in CO, H2CO, CS, and CN while they remain undetected in SO2, HDO, and CH3OH. From the absorption of the back-side outflow, we inferred that the disk emission is optically thick in the inner 50 au. This morphology explains why no line emission is detected from this inner region and poses some limitations toward the calculation of the dust mass and the characterization of the inner gaseous disk. The H2CO and CS emission from the inner 200 au is mostly from the disk and their morphology is very similar. The CN emission significantly differs from the other two molecules as it is observed only beyond 150 au. This ring-like morphology is consistent with previous observations and the predictions of thermochemical disk models. Finally, we constrained the disk-integrated column density of all molecules. In particular, we found that the CH3OH/H2CO ratio must be smaller than 2, making the methanol non-detection still consistent with the only such a ratio available from the literature (1.27 in TW Hya)., Comment: 13 pages, 6 figures, accepted by A&A

Recent ALMA observations of the protoplanetary disc around HD~169142 reveal a peculiar structure made of concentric dusty rings: a main ring at $\sim$20 au, a triple system of rings at $\sim 55-75$ au in millimetric continuum emission and a perturbed gas surface density from the $^{12}$CO,$^{13}$CO and C$^{18}$O$(J=2-1)$ surface brightness profile. In this Letter, we perform three-dimensional numerical simulations and radiative transfer modeling exploring the possibility that two giant planets interacting with the disc and orbiting in resonant locking can be responsible for the origin of the observed dust inner rings structure. We find that in this configuration the dust structure is actually long lived while the gas mass of the disc is accreted onto the star and the giant planets, emptying the inner region. In addition, we also find that the innermost planet is located at the inner edge of the dust ring, and can accrete mass from the disc, generating a signature in the dust ring shape that can be observed in mm ALMA observations., 8 pages, 5 figures, accepted Apj Letters

We report the discovery of a low-mass stellar companion around the young Herbig Be star MWC 297. We performed multi-epoch high-contrast imaging in the near infrared (NIR) with the Very Large Telescope (VLT)/Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. The companion is found at projected separation of 244.7$\pm$13.2 au and a position angle of 176.4$\pm$0.1 deg. The large separation supports formation via gravitational instability. From the spectrum, we estimate a mass of 0.1-0.5 M$_{\odot}$, the range conveying uncertainties in the extinction of the companion and in evolutionary models at young ages. The orbit coincides with a gap in the dust disk inferred from the Spectral Energy Distribution (SED). The young age ($\lesssim$ 1 Myr) and mass ratio with the central star ($\sim 0.01$) makes the companion comparable to PDS 70~b, suggesting a relation between formation scenarios and disk dynamics., Comment: 4 figures

The disc surrounding PDS 70, with two directly imaged embedded giant planets, is an ideal laboratory to study planet-disc interaction. We present three-dimensional smoothed particle hydrodynamics simulations of the system. In our simulations, planets, which are free to migrate and accrete mass, end up in a locked resonant configuration that is dynamically stable. We show that features observed at infrared (scattered light) and millimetre (thermal continuum) wavelengths are naturally explained by the accretion stream onto the outer planet, without requiring a circumplanetary disc around planet c. We post-processed our near-infrared synthetic images in order to account for observational biases known to affect high-contrast images. Our successful reproduction of the observations indicates that planet-disc dynamical interactions alone are sufficient to explain the observations of PDS 70., 15 pages, 11 figures

Direct imaging is a tried and tested method of detecting exoplanets in the near infrared, but has so far not been extended to longer wavelengths. New data at mid-IR wavelengths (8-20{\mu}m) canprovide additional constraints on planetary atmospheric models. We use the VISIR instrumenton the VLT to detect or set stringent limits on the 8.7{\mu}m flux of the four planets surrounding HR8799, and to search for additional companions. We use a novel circularised PSF subtractiontechnique to reduce the stellar signal and obtain instrument limited background levels andobtain optimal flux limits. The BT SETTL isochrones are then used to determine the resultingmass limits. We find flux limits between 0.7 and 3.3 mJy for the J8.9 flux of the differentplanets at better than5{\sigma}level and derive a new mass limit of 30 MJupfor any objects beyond40 AU. While this work has not detected planets in the HR 8799 system at 8.7{\mu}m, it has foundthat an instrument with the sensitivity of VISIR is sufficient to detect at least 4 known hotplanets around close stars, including\b{eta}Pictoris b (1700 K, 19 pc), with more than5{\sigma}certaintyin 10 hours of observing time in the mid-IR., Comment: Published in MNRAS, 5 pages, 5 figures

Planet-forming disks are not isolated systems. Their interaction with the surrounding medium affects their mass budget and chemical content. In the context of the ALMA-DOT program, we obtained high-resolution maps of assorted lines from six disks that are still partly embedded in their natal envelope. In this work, we examine the SO and SO$_2$ emission that is detected from four sources: DG Tau, HL Tau, IRAS 04302+2247, and T Tau. The comparison with CO, HCO$^+$, and CS maps reveals that the SO and SO$_2$ emission originates at the intersection between extended streamers and the planet-forming disk. Two targets, DG Tau and HL Tau, offers clear cases of inflowing material inducing an accretion shock on the disk material. The measured rotational temperatures and radial velocities are consistent with this view. In contrast to younger Class 0 sources, these shocks are confined to the specific disk region impacted by the streamer. In HL Tau, the known accreting streamer induces a shock in the disk outskirt, and the released SO and SO$_2$ molecules spiral toward the star in a few hundreds years. These results suggest that shocks induced by late accreting material may be common in the disks of young star-forming regions with possible consequences on the chemical composition and mass content of the disk. They also highlight the importance of SO and SO$_2$ line observations to probe accretion shocks from a larger sample., 18 pages, 13 figures, accepted by A$\&$A

This paper reports on a new analysis of archival ALMA $870\,\mu$m dust continuum observations. Along with the previously observed bright inner ring ($r \sim 20-40\,$au), two addition substructures are evident in the new continuum image: a wide dust gap, $r \sim 40-150\,$au, and a faint outer ring ranging from $r \sim 150\,$au to $r \sim 250\,$au and whose presence was formerly postulated in low-angular-resolution ALMA cycle 0 observations but never before observed. Notably, the dust emission of the outer ring is not homogeneous, and it shows two prominent azimuthal asymmetries that resemble an eccentric ring with eccentricity $e = 0.07 $. The characteristic double-ring dust structure of HD 100546 is likely produced by the interaction of the disk with multiple giant protoplanets. This paper includes new smoothed-particle-hydrodynamic simulations with two giant protoplanets, one inside of the inner dust cavity and one in the dust gap. The simulations qualitatively reproduce the observations, and the final masses and orbital distances of the two planets in the simulations are 3.1 $M_{J}$ at 15 au and 8.5 $M_{J}$ at 110 au, respectively. The massive outer protoplanet substantially perturbs the disk surface density distribution and gas dynamics, producing multiple spiral arms both inward and outward of its orbit. This can explain the observed perturbed gas dynamics inward of 100 au as revealed by ALMA observations of CO. Finally, the reduced dust surface density in the $\sim 40-150\,$au dust gap can nicely clarify the origin of the previously detected H$_2$O gas and ice emission., Comment: Accepted for publication

The role of bipolar jets in the formation of stars, and in particular how they are launched, is still not well understood. We probe the protostellar jet launching mechanism, via high resolution observations of the near-IR [FeII] 1.53,1.64 micron lines. We consider the bipolar jet from the Classical T Tauri star, DO Tau, & investigate jet morphology & kinematics close to the star, using AO-assisted IFU observations from GEMINI/NIFS. The brighter, blue-shifted jet is collimated quickly after launch. This early collimation requires the presence of magnetic fields. We confirm velocity asymmetries between the two jet lobes, & confirm no time variability in the asymmetry over a 20 year interval. This sustained asymmetry is in accordance with recent simulations of magnetised disk-winds. We examine the data for jet rotation. We report an upper limit on differences in radial velocity of 6.3 & 8.7 km/s for the blue & red-shifted jets, respectively. Interpreting this as an upper limit on jet rotation implies that any steady, axisymmetric magneto-centrifugal model of jet launching is constrained to a launch radius in the disk-plane of 0.5 & 0.3 au for the blue & red-shifted jets, respectively. This supports an X-wind or narrow disk-wind model. This pertains only to the observed high velocity [FeII] emission, & does not rule out a wider flow launched from a wider radius. We report detection of small amplitude jet axis wiggling in both lobes. We rule out orbital motion of the jet source as the cause. Precession can better account for the observations but requires double the precession angle, & a different phase for the counter-jet. Such non-solid body precession could arise from an inclined massive Jupiter companion, or a warping instability induced by launching a magnetic disk-wind. Overall, our observations are consistent with an origin of the DO Tau jets from the inner regions of the disk., Accepted for publication in A&A - 18 pages, 11 figures (incl. Appendix)

We investigate the deuteration of methanol towards the high-mass star forming region NGC 7538-IRS1. We have carried out a multi-transition study of CH$_3$OH, $^{13}$CH$_3$OH and of the deuterated fllavors, CH$_2$DOH and CH$_3$OD, between 1.0--1.4 mm with the IRAM-30~m antenna. In total, 34 $^{13}$CH$_3$OH, 13 CH$_2$DOH lines and 20 CH$_3$OD lines spanning a wide range of upper-state energies (E$_{up}$) were detected. From the detected transitions, we estimate that the measured D/H does not exceed 1$\%$, with a measured CH$_2$DOH/CH$_3$OH and CH$_3$OD/CH$_3$OH of about (32$\pm$8)$\times$10$^{-4}$ and (10$\pm$4)$\times$10$^{-4}$, respectively. This finding is consistent with the hypothesis of a short-time scale formation during the pre-stellar phase. We find a relative abundance ratio CH$_2$DOH/CH$_3$OD of 3.2 $\pm$ 1.5. This result is consistent with a statistical deuteration. We cannot exclude H/D exchanges between water and methanol if water deuteration is of the order 0.1$\%$, as suggested by recent Herschel observations., Comment: Accepted for publication in Astronomy & Astrophysics

Aims. R Coronae Australis (R CrA) is the brightest star of the Coronet nebula of the Corona Australis (CrA) star forming region. It has very red colors, probably due to dust absorption and it is strongly variable. High contrast instruments allow for an unprecedented direct exploration of the immediate circumstellar environment of this star. Methods. We observed R CrA with the near-IR channels (IFS and IRDIS) of SPHERE at VLT. In this paper, we used four different epochs, three of them from open time observations while one is from the SPHERE guaranteed time. The data were reduced using the DRH pipeline and the SPHERE Data Center. On the reduced data we implemented custom IDL routines with the aim to subtract the speckle halo.We have also obtained pupil-tracking H-band (1.45-1.85 micron) observations with the VLT/SINFONI near-infrared medium-resolution (R~3000) spectrograph. Results. A companion was found at a separation of 0.156" from the star in the first epoch and increasing to 0.18400 in the final one. Furthermore, several extended structures were found around the star, the most noteworthy of which is a very bright jet-like structure North-East from the star. The astrometric measurements of the companion in the four epochs confirm that it is gravitationally bound to the star. The SPHERE photometry and the SINFONI spectrum, once corrected for extinction, point toward an early M spectral type object with a mass between 0.3 and 0.55 M?. The astrometric analyis provides constraints on the orbit paramenters: e~0.4, semi-major axis at 27-28 au, inclination of ~ 70{\deg} and a period larger than 30 years. We were also able to put constraints of few MJup on the mass of possible other companions down to separations of few tens of au., Comment: 11 pages, 13 figures, accepted by A&A

The formation of planets occurs within protoplanetary disks surrounding young stars, resulting in perturbation of the gas and dust surface densities. Here we report the first evidence of spatially resolved gas surface density (Σ g ) perturbation toward the AS 209 protoplanetary disk from the optically thin C18O (J = 2-1) emission. The observations were carried out at 1.3 mm with Atacama Large Millimeter/submillimeter Array at a spatial resolution of about 0.″3 0.″2 (corresponding to ~38 25 au). The C18O emission shows a compact (≤60 au), centrally peaked emission and an outer ring peaking at 140 au, consistent with that observed in the continuum emission, and its azimuthally averaged radial intensity profile presents a deficit that is spatially coincident with the previously reported dust map. This deficit can only be reproduced with our physico-thermochemical disk model by lowering Σgas by nearly an order of magnitude in the dust gaps. Another salient result is that, contrary to C18O, the DCO+ (J = 3-2) emission peaks between the two dust gaps. We infer that the best scenario to explain our observations (C18O deficit and DCO+ enhancement) is a gas perturbation due to one or more forming planets, which is commensurate with previous continuum observations of the source along with hydrodynamical simulations. Our findings confirm that the previously observed dust gaps are very likely due to perturbation of the gas surface density that is induced by a planet of at least 0.2M J in formation. Finally, our observations also show the potential of using CO isotopologues to probe the presence of one or more Saturn-mass planets.

The combination of high-resolution and sensitivity offered by ALMA is revolutionizing our understanding of protoplanetary discs, as their bulk gas and dust distributions can be studied independently. In this paper we present resolved ALMA observations of the continuum emission (λ = 1.3 mm) and CO isotopologues (12CO, 13CO, C18O, J = 2 - 1) integrated intensity from the disc around the nearby (d = 162 pc), intermediate-mass (M_{\star }=1.67 M_{\odot }) pre-main-sequence star CQ Tau. The data show an inner depression in continuum and in both 13CO and C18O emission. We employ a thermo-chemical model of the disc reproducing both continuum and gas radial intensity profiles, together with the disc spectral energy distribution. The models show that a gas inner cavity with size between 15 and 25 au is needed to reproduce the data with a density depletion factor between ~10-1 and ~10-3. The radial profile of the distinct cavity in the dust continuum is described by a Gaussian ring centred at R_dust=53 au and with a width of σ =13 au. Three-dimensional gas and dust numerical simulations of a disc with an embedded planet at a separation from the central star of {~ }20 au and with a mass of {~ } 6 - 9 M_Jup reproduce qualitatively the gas and dust profiles of the CQ Tau disc. However, a one-planet model appears not to be able to reproduce the dust Gaussian density profile predicted using the thermo-chemical modeling.

We report the results of a survey on the [OI]6300A line emission in 131 T Tauri stars of the Lupus, Chamaeleon and σ Orionis star forming regions, observed with the X-shooter spectrograph at the Very Large Telescope (VLT). The line profile was deconvolved into a low velocity component (LVC, ∣Vr∣ 40 km s−1), originating from slow winds and high velocity jets, respectively. The LVC is by far the most frequent component, with a detection rate of 77%, while only 30% of sources have a HVC. The [OI]6300A luminosity of both the LVC and HVC, when detected, correlates with stellar and accretion parameters of the central sources with similar slopes for the two components. Mass ejection rates (\({\dot {M}_{jet}}\)) measured from the detected HVC [OI]6300A line luminosity span from ∼10−13 to ∼10−7 M⊙ yr−1 and the corresponding \({\dot {M}_{jet}}\)/\({\dot {M}_{acc}}\) ratio ranges from ∼0.01 to ∼0.5, with an average value of 0.07. However, considering the upper limits on the HVC, we infer a \({\dot {M}_{jet}}\)/\({\dot {M}_{acc}}\) ratio < 0.03 in more than 40% of sources. We argue that most of these sources might lack the physical conditions needed for an efficient magneto-centrifugal acceleration in the star-disc interaction region.

Planets form in protoplanetary disks and inherit their chemical compositions. It is thus crucial to map the distribution and investigate the formation of simple organics, such as formaldehyde and methanol, in protoplanetary disks. We analyze ALMA observations of the nearby disk-jet system around the T Tauri star DG Tau in the o-H$_2$CO $3_{1,2}-2_{1,1}$ and CH$_3$OH $3_{-2,2}-4_{-1,4}$ E, $5_{0,5}-4_{0,4}$ A transitions at an unprecedented resolution of $\sim0.15"$, i.e., $\sim18$ au at a distance of 121 pc. The H$_2$CO emission originates from a rotating ring extending from $\sim40$ au with a peak at $\sim62$ au, i.e., at the edge of the 1.3mm dust continuum. CH$_3$OH emission is not detected down to an r.m.s. of 3 mJy/beam in the 0.162 km/s channel. Assuming an ortho-to-para ratio of 1.8-2.8 the ring- and disk-height-averaged H$_2$CO column density is $\sim0.3-4\times10^{14}$ cm$^{-2}$, while that of CH$_3$OH is $, 8 pages, 6 figures, accepted for publication on A&A Letters

Hydrogen deuteride (HD) rotational line emission can provide reliable protoplanetary disk gas mass measurements, but it is difficult to observe and detections have been limited to three T-Tauri disks. No new data have been available since the \emph{Herschel} Space Observatory mission ended in 2013. We set out to obtain new disk gas mass constraints by analysing upper limits on HD 1-0 emission in \emph{Herschel}/PACS archival data from the DIGIT key programme. With a focus on the Herbig Ae/Be disks, whose stars are more luminous than T Tauris, we determine upper limits for HD in data previosly analysed for its line detections. Their significance is studied with a grid of models run with the DALI physical-chemical code, customised to include deuterium chemistry. Nearly all the disks are constrained to $M_{\rm gas}\leq0.1\,$M$_{\odot}$, ruling out global gravitational instability. A strong constraint is obtained for the HD 163296 disk mass, $M_{\rm gas} \leq 0.067\,$M$_{\odot}$, implying $\Delta_{\rm g/d}\leq100$. This HD-based mass limit is towards the low end of CO-based mass estimates for the disk, highlighting the large uncertainty in using only CO and suggesting that gas-phase CO depletion in HD 163296 is at most a factor of a few. The $M_{\rm gas}$ limits for HD 163296 and HD 100546, both bright disks with massive candidate protoplanetary systems, suggest disk-to-planet mass conversion efficiencies of $M_{\rm p}/(M_{\rm gas} + M_{\rm p})\approx10$ to $40\,$% for present-day values. Near-future observations with SOFIA/HIRMES will be able to detect HD in the brightest Herbig~Ae/Be disks within $150\,$pc with $\approx10\,$h integration time., Comment: Accepted for publication in A&A

The mechanism for jet formation in the disks of T Tauri stars is poorly understood. Observational benchmarks to launching models can be provided by tracing the physical properties of the kinematic components of the wind and jet in the inner 100 au of the disk surface. In the framework of the GHOsT (GIARPS High-resolution Observations of T Tauri stars) project, we aim to perform a multi-line analysis of the velocity components of the gas in the jet acceleration zone. We analyzed the GIARPS-TNG spectra of six objects in the Taurus-Auriga complex (RY Tau, DG Tau, DL Tau, HN Tau, DO Tau, RW Aur A). Thanks to the combined high-spectral resolution (R=50000-115000) and wide spectral coverage (~400-2400 nm) we observed several O, S+, N, N+, and Fe+ forbidden lines spanning a large range of excitation and ionization conditions. In four objects (DG Tau, HN Tau, DO Tau, RW Aur A), temperature (T_e), electron and total density (n_e, n_H), and fractional ionization (x_e) were derived as a function of velocity through an excitation and ionization model. The abundance of gaseous iron, X(Fe), a probe of the dust content in the jet, was derived in selected velocity channels. The physical parameters vary smoothly with velocity, suggesting a common origin for the different kinematic components. In DG Tau and HN Tau, T_e, x_e, and X(Fe) increase with velocity (roughly from 6000 K, 0.05, 10% X(Fe)_sun to 15000 K, 0.6, 90% X(Fe)_sun). This trend is in agreement with disk-wind models in which the jet is launched from regions of the disk at different radii. In DO Tau and RW Aur A, we infer x_e < 0.1, n_H ~10^6-7 cm^-3, and X(Fe), Comment: Accepted by A&A

We present an overview of the ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT), a campaign devoted to the characterization of the molecular emission from partly embedded, young stars. The project aims at better understanding the gaseous products that are delivered to planets by means of high-resolution maps of assorted lines probing disks at the time of the planet formation (less than 1 Myr). Nine different molecules are surveyed by our observations of six Class I/flat-spectrum sources. A series of accompanying articles analyze specific targets and molecules. Here we describe the sample and provide a general overview of the results, focusing on the spatial distribution, column densities, and abundance ratios of H$_2$CO, CS, and CN. The results of this work are a first step toward the characterization of the disk chemical evolution that need to be complemented by further observations of less exceptional disks and customized thermo-chemical modeling., Accepted for publication by A&A, 16 pages, 9 figures

Aims: To trace the radial and vertical spatial distribution of H2CS, a key species of the S-bearing chemistry, in protoplanetary disks. To analyse the observed distributions in light of the H2CS binding energy, in order to discuss the role of thermal desorption in enriching the gas disk component. Methods: In the context of the ALMA chemical survey of Disk-Outflow sources in the Taurus star forming region (ALMA-DOT), we observed five Class I or early Class II sources with the o-H2CS(7_1,6-6_1,5) line on a 40 au scale. We estimated the binding energy (BEs) of H2CS using quantum mechanical calculations, for the first time, for an extended, periodic, crystalline ice. Results: We imaged H2CS in two rotating molecular rings in the HL Tau and IRAS04302+2247 disks. The outer radii are about 140 au (HL Tau), and 115 au (IRAS 04302+2247). The edge-on geometry of IRAS 04302+2247 reveals that H2CS emission peaks, at radii of 60-115 au, at z = +- 50 au from the equatorial plane. The column densities are about 10^14 cm^-2. For HL Tau, we derive, for the first time, the [H2CS]/[H] abundance in a protoplanetary disk (about 10^-14). The BEs of H2CS computed for extended crystalline ice and amorphous ices is 4258 K and 3000-4600 K, respectively, implying a thermal evaporation where dust temperature is larger than 50-80 K. Conclusions: H2CS traces the so-called warm molecular layer, a region previously sampled using CS, and H2CO. Thioformaldehyde peaks closer to the protostar than H2CO and CS, plausibly due to the relatively high-excitation level of observed 7_1,6-6_1,5 line (60 K). The H2CS BEs implies that thermal desorption dominates in thin, au-sized, inner and/or upper disk layers, indicating that the observed H2CS emitting up to radii larger than 100 au is likely injected in the gas due to non-thermal processes., A&A, in press

The chemical composition of planets is inherited from that of the protoplanetary disk at the time of planet formation. Increasing observational evidence suggests that planet formation occurs in less than 1 Myr. This motivates the need for spatially resolved spectral observations of Class I disks, as carried out by the ALMA chemical survey of Disk-Outflow sources in Taurus (ALMA-DOT). In the context of ALMA-DOT, we observe the edge-on disk around the Class I source IRAS 04302+2247 (the butterfly star) in the 1.3mm continuum and five molecular lines. We report the first tentative detection of methanol (CH$_3$OH) in a Class I disk and resolve, for the first time, the vertical structure of a disk with multiple molecular tracers. The bulk of the emission in the CO 2-1, CS 5-4, and o-H$_2$CO 3(1,2)-2(1,1) lines originates from the warm molecular layer, with the line intensity peaking at increasing disk heights, $z$, for increasing radial distances, $r$. Molecular emission is vertically stratified, with CO observed at larger disk heights (aperture $z/r\sim0.41-0.45$) compared to both CS and H$_2$CO, which are nearly cospatial ($z/r\sim0.21-0.28$). In the outer midplane, the line emission decreases due to molecular freeze-out onto dust grains (freeze-out layer) by a factor of >100 (CO) and 15 (CS). The H$_2$CO emission decreases by a factor of only about 2, which is possibly due to H$_2$CO formation on icy grains, followed by a nonthermal release into the gas phase. The inferred [CH$_3$OH]/[H$_2$CO] abundance ratio is 0.5-0.6, which is 1-2 orders of magnitude lower than for Class 0 hot corinos, and a factor ~2.5 lower than the only other value inferred for a protoplanetary disk (in TW Hya, 1.3-1.7). Additionally, it is at the lower edge but still consistent with the values in comets. This may indicate that some chemical reprocessing occurs in disks before the formation of planets and comets., 8 pages, 4 figures, accepted for publication as a letter on A&A

We present polarimetric data of CW Tau and DG Tau, two well-known Class II disk/jet systems, obtained with the Atacama Large Millimeter/submillimeter Array at 870 $\mu$m and 0."2 average resolution. In CW Tau, the total and polarized emission are both smooth and symmetric, with polarization angles almost parallel to the minor axis of the projected disk. In contrast, DG Tau displays a structured polarized emission, with an elongated brighter region in the disk's near side and a belt-like feature beyond about 0."3 from the source. At the same time the total intensity is spatially smooth, with no features. The polarization pattern, almost parallel to the minor axis in the inner region, becomes azimuthal in the outer belt, possibly because of a drop in optical depth. The polarization fraction has average values of 1.2% in CW Tau and 0.4% in DG Tau. Our results are consistent with polarization from self-scattering of the dust thermal emission. Under this hypothesis, the maximum size of the grains contributing to polarization is in the range 100 - 150 $\mu$m for CW Tau and 50 - 70 $\mu$m for DG Tau. The polarization maps combined with dust opacity estimates indicate that these grains are distributed in a geometrically thin layer in CW Tau, representing a settling in the disk midplane. Meanwhile, such settling is not yet apparent for DG Tau. These results advocate polarization studies as a fundamental complement to total emission observations, in investigations of the structure and the evolution of protoplanetary disks., Comment: 8 pages, 5 figures. Accepted for publication in ApJ Letters

The formation of asteroids, comets and planets occurs in the interior of protoplanetary disks during the early phase of star formation. Consequently, the chemical composition of the disk might shape the properties of the emerging planetary system. In this context, it is crucial to understand whether and what organic molecules are synthesized in the disk. In this Letter, we report the first detection of formic acid (HCOOH) towards the TW Hydrae protoplanetary disk. The observations of the trans-HCOOH 6$_{(1,6)-5(1,5)}$ transition were carried out at 129~GHz with ALMA. We measured a disk-averaged gas-phase t-HCOOH column density of $\sim$ (2-4)$\times$10$^{12}$~cm$^{-2}$, namely as large as that of methanol. HCOOH is the first organic molecules containing two oxygen atoms detected in a protoplanetary disk, a proof that organic chemistry is very active even though difficult to observe in these objects. Specifically, this simplest acid stands as the basis for synthesis of more complex carboxylic acids used by life on Earth., Comment: 9 pages, 4 figures, 1 table, published online in ApJL on 16th July 2018

This work aims to understand which midplane conditions are probed by the DCO$^+$ emission in the disk around the Herbig Ae star HD 169142. We explore the sensitivity of the DCO$^+$ formation pathways to the gas temperature and the CO abundance. The DCO$^+$ $J$=3-2 transition was observed with ALMA at a spatial resolution of 0.3". The HD 169142 DCO$^+$ radial intensity profile reveals a warm, inner component at radii 120 AU. The warm deuterium fractionation pathway is implemented as a constant DCO$^+$ abundance of 2.0$\times$10$^{-12}$ between 30-70 K. The DCO$^+$ emission probes a reservoir of cold material in the HD 169142 outer disk that is not revealed by the millimeter continuum, the SED, nor the emission from the 12CO, 13CO, or C18O $J$=2-1 lines., Accepted to Astronomy & Astrophysics

Extensive surveys of star-forming regions with Spitzer have revealed populations of disk-bearing young stellar objects. These have provided crucial constraints, such as the timescale of dispersal of protoplanetary disks, obtained by carefully combining infrared data with spectroscopic or X-ray data. While observations in various regions agree with the general trend of decreasing disk fraction with age, the Lupus V and VI regions appeared to have been at odds, having an extremely low disk fraction. Here we show, using the recent Gaia data release 2 (DR2), that these extremely low disk fractions are actually due to a very high contamination by background giants. Out of the 83 candidate young stellar objects (YSOs) in these clouds observed by Gaia, only five have distances of 150 pc, similar to YSOs in the other Lupus clouds, and have similar proper motions to other members in this star-forming complex. Of these five targets, four have optically thick (Class II) disks. On the one hand, this result resolves the conundrum of the puzzling low disk fraction in these clouds, while, on the other hand, it further clarifies the need to confirm the Spitzer selected diskless population with other tracers, especially in regions at low galactic latitude like Lupus V and VI. The use of Gaia astrometry is now an independent and reliable way to further assess the membership of candidate YSOs in these, and potentially other, star-forming regions., Accepted for publication on Astronomy&Astrophysics Letters

Context. Several sulfur-bearing molecules are observed in the interstellar medium and in comets, in strong contrast to protoplanetary disks where only CS, H$_2$CS and SO have been detected so far. Aims. We combine observations and chemical models to constrain the sulfur abundances and their sensitivity to physical and chemical conditions in the DM Tau protoplanetary disk. Methods. We obtained $0.5^{"}$ ALMA observations of DM Tau in Bands 4 and 6 in lines of CS, SO, SO$_2$, OCS, CCS, H$_2$CS and H$_2$S, achieving a $\sim 5$ mJy sensitivity. Using the non-LTE radiative transfer code RADEX and the forward-modeling tool DiskFit, disk-averaged CS column densities and upper limits for the other species were derived. Results. Only CS was detected with a derived column density of $\sim 2-6 \times 10^{12}$ cm$^{-2}$. We report a first tentative detection of SO$_2$ in DM Tau. The upper limits range between $\sim 10^{11}$ and $10^{14}$ cm$^{-2}$ for the other S-bearing species. The best-fit chemical model matching these values requires a gas-phase C/O ratio of > 1 at $r \sim 50-100$ au. With chemical modeling we demonstrate that sulfur-bearing species could be robust tracers of the gas-phase C/O ratio, surface reaction rates, grain size and UV intensities. Conclusions. The lack of detections of a variety of sulfur-bearing molecules in DM Tau other than CS implies a dearth of reactive sulfur in the gas phase, either through efficient freeze-out or because most of the elemental sulfur is in other large species, as found in comets. The inferred high CS/SO and CS/SO$_2$ ratios require a non-solar C/O gas-phase ratio of > 1, consistent with the recent observations of hydrocarbon rings in DM Tau. The stronger depletion of oxygen-bearing S-species compared to CS is likely linked to the low observed abundances of gaseous water in DM Tau and points to a removal mechanism of oxygen from the gas., Accepted by Astronomy & Astrophysics (15 pages, 15 figures, 8 tables)

We have analysed the [OI]6300 A line in a sample of 131 young stars with discs in the Lupus, Chamaeleon and signa Orionis star forming regions, observed with the X-shooter spectrograph at VLT. The stars have mass accretion rates spanning from 10^{-12} to 10^{-7} Mo/yr. The line profile was deconvolved into a low velocity component (LVC, < 40 km/s) and a high velocity component (HVC, > 40 km/s ), originating from slow winds and high velocity jets, respectively. The LVC is by far the most frequent component, with a detection rate of 77%, while only 30% of sources have a HVC. The [OI]6300 luminosity of both the LVC and HVC, when detected, correlates with stellar and accretion parameters of the central sources (i.e. Lstar , Mstar , Lacc , Macc), with similar slopes for the two components. The line luminosity correlates better with the accretion luminosity than with the stellar luminosity or stellar mass. We suggest that accretion is the main drivers for the line excitation and that MHD disc-winds are at the origin of both components. In the sub-sample of Lupus sources observed with ALMA a relationship is found between the HVC peak velocity and the outer disc inclination angle, as expected if the HVC traces jets ejected perpendicularly to the disc plane. Mass loss rates measured from the HVC span from ~ 10^{-13} to ~10^{-7} Mo/yr. The corresponding Mloss/Macc ratio ranges from ~0.01 to ~0.5, with an average value of 0.07. However, considering the upper limits on the HVC, we infer a ratio < 0.03 in more than 40% of sources. We argue that most of these sources might lack the physical conditions needed for an efficient magneto-centrifugal acceleration in the star-disc interaction region. Systematic observations of populations of younger stars, that is, class 0/I, are needed to explore how the frequency and role of jets evolve during the pre-main sequence phase., 15 pages, 14 figures, Accepted for publication in A&A

The nearby Eta Chamaeleontis association is a collection of 4-10 Myr old stars with a disk fraction of 35-45%. In this study, the broad wavelength coverage of VLT/X-Shooter is used to measure the stellar and mass accretion properties of 15 low mass stars in the Eta Chamaeleontis association. For each star, the observed spectrum is fitted with a non-accreting stellar template and an accretion spectrum obtained from assuming a plane-parallel hydrogen slab. Five of the eight stars with an IR disk excess show excess UV emission, indicating ongoing accretion. The accretion rates measured here are similar to those obtained from previous measurements of excess UV emission, but tend to be higher than past measurements from H-alpha modeling. The mass accretion rates are consistent with those of other young star forming regions., Accepted for publication in Astronomy & Astrophysics