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The G31.41+0.31 Unbiased ALMA sPectral Observational Survey (GUAPOS) project targets the hot molecular core (HMC) G31.41+0.31 (G31), to unveil the complex chemistry of one of the most chemically rich high-mass star-forming regions outside the Galactic Center (GC). In the third paper of the project, we present a study of nine O-bearing (CH$_3$OH, $^{13}$CH$_3$OH, CH$_3^{18}$OH, CH$_3$CHO, CH$_3$OCH$_3$, CH$_3$COCH$_3$ , C$_2$H$_5$OH, aGg'-(CH$_2$OH)$_2$, and gGg'-(CH$_2$OH)$_2$) and six N-bearing (CH$_3$CN, $^{13}$CH$_3$CN, CH$_3^{13}$CN, C$_2$H$_3$CN, C$_2$H$_5$CN, and C$_2$H$_5^{13}$CN) complex organic molecules toward G31. The aim of this work is to characterize the abundances in one of the most chemically-rich hot molecular cores outside the GC and to search for a possible chemical segregation between O-bearing and N-bearing species in G31, which hosts four compact sources as seen with higher angular resolution data. Observations were carried out with the interferometer ALMA and covered the entire Band 3 from 84 to 116 GHz ($\sim 32$ GHz bandwidth) with an angular resolution of $1.2''$ ($\sim4400\,\mathrm{au}$). The spectrum has been analyzed with the tool SLIM of MADCUBA to determine the physical parameters of the emitting gas. Moreover, we have analyzed the morphology of the emission of the molecular species. We have compared the abundances w.r.t methanol of COMs in G31 with other twenty-seven sources, including other hot molecular cores inside and outside the Galactic Center, hot corinos, shocked regions, envelopes around young stellar objects, and quiescent molecular clouds, and with chemical models. Different species peak at slightly different positions, and this, together with the different central velocities of the lines obtained from the spectral fitting, point to chemical differentiation of selected O-bearing species., Comment: accepted for publication in A&A, 39 pages

Early dust grain growth in protostellar envelopes infalling on young discs has been suggested in recent studies, supporting the hypothesis that dust particles start to agglomerate already during the Class 0/I phase of young stellar objects (YSOs). If this early evolution were confirmed, it would impact the usually assumed initial conditions of planet formation, where only particles with sizes $\lesssim 0.25 \mu$m are usually considered for protostellar envelopes. We aim to determine the maximum grain size of the dust population in the envelope of the Class 0/I protostar L1527 IRS, located in the Taurus star-forming region (140 pc). We use Atacama Large millimetre/sub-millimetre Array (ALMA) and Atacama Compact Array (ACA) archival data and present new observations, in an effort to both enhance the signal-to-noise ratio of the faint extended continuum emission and properly account for the compact emission from the inner disc. Using observations performed in four wavelength bands and extending the spatial range of previous studies, we aim to place tight constraints on the spectral ($\alpha$) and dust emissivity ($\beta$) indices in the envelope of L1527 IRS. We find a rather flat $\alpha \sim$ 3.0 profile in the range 50-2000 au. Accounting for the envelope temperature profile, we derive values for the dust emissivity index, 0.9 < $\beta$ < 1.6, and reveal a tentative, positive outward gradient. This could be interpreted as a distribution of mainly ISM-like grains at 2000 au, gradually progressing to (sub-)millimetre-sized dust grains in the inner envelope, where at R=300 au, $\beta$ = 1.1 +/- 0.1. Our study supports a variation of the dust properties in the envelope of L1527 IRS. We discuss how this can be the result of in-situ grain growth, dust differential collapse from the parent core, or upward transport of disc large grains., Comment: Accepted for publication in A&A. Contains 18 pages, 21 figures, 5 tables

Methanol is a ubiquitous species commonly found in the molecular interstellar medium. It is also a crucial seed species for the building-up of the chemical complexity in star forming regions. Thus, understanding how its abundance evolves during the star formation process and whether it enriches the emerging planetary system is of paramount importance. We used new data from the ALMA Large Program FAUST (Fifty AU STudy of the chemistry in the disk/envelope system of Solar-like protostars) to study the methanol line emission towards the [BHB2007] 11 protobinary system (sources A and B), where a complex structure of filaments connecting the two sources with a larger circumbinary disk has been previously detected. Twelve methanol lines have been detected with upper energies in the range [45-537] K along with one 13CH3OH transition. The methanol emission is compact and encompasses both protostars, separated by only 28 au and presents three velocity components, not spatially resolved by our observations, associated with three different spatial regions, with two of them close to 11B and the third one associated with 11A. A non-LTE radiative transfer analysis of the methanol lines concludes that the gas is hot and dense and highly enriched in methanol with an abundance as high as 1e-5. Using previous continuum data, we show that dust opacity can potentially completely absorb the methanol line emission from the two binary objects. Although we cannot firmly exclude other possibilities, we suggest that the detected hot methanol is resulting from the shocked gas from the incoming filaments streaming towards [BHB2007] 11 A and B, respectively. Higher spatial resolution observations are necessary to confirm this hypothesis., Comment: 17 pages, accepted in A&A

The outer Galaxy is an environment with metallicity lower than the Solar one. Because of this, the formation and survival of molecules in star-forming regions located in the inner and outer Galaxy is expected to be different. To gain understanding on how chemistry changes throughout the Milky Way, it is crucial to observe outer Galaxy star-forming regions to constrain models adapted for lower metallicity environments. In this paper we present a new observational project: chemical complexity in star-forming regions of the outer Galaxy (CHEMOUT). The goal is to unveil the chemical composition in 35 dense molecular clouds associated with star-forming regions of the outer Galaxy through observations obtained with the IRAM 30m telescope. In this first paper, we present the sample, and report the detection at 3~mm of simple organic species HCO+, H13CO+, HCN, c-C3H2, HCO, C4H, and HCS+, of the complex hydrocarbon CH3CCH, and of SiO, CCS and SO. From c-C3H2, we estimate new kinematic heliocentric and Galactocentric distances based on an updated rotation curve of the Galaxy. The detection of the molecular tracers does not seem to have a clear dependence on the Galactocentric distance. We also analyse the HCO+ line profiles. We find high velocity wings in ~71% of the targets, and their occurrence does not depend on the Galactocentric distance. Our results, confirmed by a statistical analysis, show that the presence of organic molecules and tracers of protostellar activity is ubiquitous in the low-metallicity environment of the outer Galaxy. Based on this, and on the additional evidence that small, terrestrial planets are omnipresent in the Galaxy, we support previous claims that the definition of Galactic Habitable Zone should be rediscussed in view of the ubiquitous capacity of the interstellar medium to form organic molecules., Comment: 11 pages, 5 figures, 3 appendices, accepted for publication in A&A

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, Accepted for publication on Astronomy & Astrophysics. 15 pages + appendix, language edited version

Class III stars are those in star forming regions without large non-photospheric infrared emission, suggesting recent dispersal of their protoplanetary discs. We observed 30 class III stars in the 1–3 Myr Lupus region with ALMA at ∼856μm, resulting in four detections that we attribute to circumstellar dust. Inferred dust masses are 0.036–0.093M⊕, ∼1 order of magnitude lower than any previous measurements; one disc is resolved with radius ∼80 au. Two class II sources in the field of view were also detected, and 11 other sources, consistent with sub-mm galaxy number counts. Stacking non-detections yields a marginal detection with mean dust mass ∼0.0048M⊕. We searched for gas emission from the CO J = 3–2 line, and present its detection to NO Lup inferring a gas mass (4.9 ± 1.1) × 10−5 M⊕ and gas-to-dust ratio 1.0 ± 0.4. Combining our survey with class II sources shows a gap in the disc mass distribution from 0.09–2M⊕ for ${\gt}0.7\, \mathrm{M}_\odot$ Lupus stars, evidence of rapid dispersal of mm-sized dust from protoplanetary discs. The class III disc mass distribution is consistent with a population model of planetesimal belts that go on to replenish the debris discs seen around main sequence stars. This suggests that planetesimal belt formation does not require long-lived protoplanetary discs, i.e. planetesimals form within ∼2 Myr. While all four class III discs are consistent with collisional replenishment, for two the gas and/or mid-IR emission could indicate primordial circumstellar material in the final stages of protoplanetary disc dispersal. Two class III stars without sub-mm detections exhibit hot emission that could arise from ongoing planet formation processes inside ∼1 au.

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., Accepted on Astronomy & Astrophysics. Language edited version

Very low-mass stars are known to have jets and outflows, which is indicative of a scaled-down version of low-mass star formation. However, only very few outflows in very low-mass sources are well characterized. We characterize the bipolar molecular outflow of the very low-mass star Par-Lup3-4, a 0.12 M$_{\odot}$ object known to power an optical jet. We observed Par-Lup3-4 with ALMA in Bands 6 and 7, detecting both the continuum and CO molecular gas. In particular, we studied three main emission lines: CO(2-1), CO(3-2), and $^{13}$CO(3-2). Our observations reveal for the first time the base of a bipolar molecular outflow in a very low-mass star, as well as a stream of material moving perpendicular to the primary outflow of this source. The primary outflow morphology is consistent with the previously determined jet orientation and disk inclination. The outflow mass is $9.5\times10^{-7}\mathrm{M}_{\odot}$ , with an outflow rate of $4.3\times10^{-9}\mathrm{M}_{\odot}\mathrm{yr}^{-1}$ A new fitting to the spectral energy distribution suggests that Par-Lup3-4 may be a binary system. We have characterized Par-Lup3-4 in detail, and its properties are consistent with those reported in other very low-mass sources. This source provides further evidence that very low-mass sources form as a scaled-down version of low-mass stars., Comment: 20 pages, 11 figures, 5 tables. Accepted in A&A

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We present the Forgotten Quadrant Survey (FQS), an ESO large project that used the 12m antenna of the Arizona Radio Observatory to map the Galactic Plane in the range 220��$, 16 pages, 17 figures, accepted for publication in Astronomy and Astrophysics

Context. A good constraint of when the growth of dust grains from sub-micrometer to millimeter sizes occurs, is crucial for planet formation models. This provides the first step towards the production of pebbles and planetesimals in protoplanetary disks. Currently, it is well established that Class II objects have large dust grains. However, it is not clear when in the star formation process this grain growth occurs. Aims. We use multi-wavelength millimeter observations of a Class I protostar to obtain the spectral index of the observed flux densities α mm of the unresolved disk and the surrounding envelope. Our goal is to compare our observational results with visibility modeling at both, 1.3 and 2.7mm simultaneously. Methods. We present data from NOEMA at 2.7mm and SMA at 1.3mm of the Class I protostar, Per-emb-50. We model the dust emission with a variety of parametric and radiative-transfer models to deduce the grain size from the observed emission spectral index. Results. We find a spectral index in the envelope of Per-emb-50 of α env = 3.3 ± 0.3, similar to the typical ISM values. The radiativetransfer modeling of the source confirms this value of α env with the presence of dust with a a max ≤ 100 μm. Additionally, we explore the backwarming effect, where we find that the envelope structure affects the millimeter emission of the disk. Conclusions. Our results reveal grains with a maximum size no larger than 100 μm in the inner envelope of the Class I protostar Per-emb-50, providing an interesting case to test the universality of millimeter grain growth expected in these sources., C.A.G. acknowledges support from CONICYT-Becas Chile (grant 72160297). P.C, J.P and L.S acknowledge the financial support of the European Research Council (ERC; project 320620). L.T. acknowledges the financial support of the Italian Ministero dell’Istruzione, Universitá e Ricerca through the grant Progetti Premiali 2012 – iALMA (CUP C52I13000140001), and by the Deutsche Forschungs-gemeinschaft (DFG, German Research Foundation) – Ref no. FOR 2634/1 TE 1024/1–1. M.T. has been supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG. A.M. acknowledges an ESO Fellowship.

ALMA surveys have shown that CO emission in protoplanetary disks is much fainter than expected. Accordingly, CO-based gas masses and gas/dust ratios are orders of magnitude lower than previously thought. This may be explained either as fast gas dispersal, or as chemical evolution and locking up of volatiles in larger bodies leading to the low observed CO fluxes. The latter processes lead to enhanced C/O ratios in the gas, which may be reflected in enhanced abundances of molecules like C2H. The goal of this work is to employ C2H observations to understand whether low CO fluxes are caused by volatile depletion, or by fast gas dissipation. We present ALMA Cycle 4 C2H observations of a subsample of nine sources in Lupus. The integrated C2H emission is determined and compared to previous CO observations and model predictions. Seven out of nine disks are detected in C2H, whose line emission is almost as bright as 13CO. All detections are significantly brighter than the typical sensitivity of the observations, hinting at a bimodal distribution of the C2H line intensities. When compared with DALI models, the observed C2H fluxes can be reproduced only if some level of volatile carbon and oxygen depletion is allowed and C/O>1 in the gas. Models with reduced gas/dust ratios fail instead to reproduce the observations. A steeper than linear correlation between C2H and CN emission line is found. This is linked to the fact that C2H emission lines are affected more strongly by C/O variations than CN lines. Ring-like structures are detected both in C2H and in continuum emission but, as for CN, they do not seem to be connected. Sz 71 shows ring shaped emission in both C2H and CN with the location of the peak intensity coinciding. Our new ALMA C2H observations favour volatile carbon and oxygen depletion rather than fast gas dispersal to explain the faint CO observations for most of the disks., 11 pages, 12 figures, accepted for publication on A&A

The origin of the tight correlations observed between the masses of supermassive black holes (SMBHs) and host galaxy properties is still debated. Negative feedback from AGN can provide a viable explanation for these correlations. According to the theoretical models, the ejective feedback resulting from radiatively-efficient episodes of gas accretion onto SMBHs may be the main responsible for the rapid shut-off of star formation and black hole growth in the early stages of the evolution of present-day massive galaxies, which must have taken place at z>2. Here we present near-IR (SINFONI) and millimetre (ALMA) observations of z~2.5 luminous (Lbol>1e47 Lsun) quasars showing fast and extended ionised outflows. These AGN-driven outflows appear to be able to expel a large fraction of molecular and ionised gas and suppress star formation in the outflow region. However, the detection of Halpha emission along the edges of the outflow cone indicates on-going star formation rates of at least 50 Msun/yr, suggesting either that AGN feedback does not affect the whole galaxy or that many feedback episodes are required before star formation is completely quenched. On the other hand, the detection also lead to a positive feedback interpretation: the AGN-driven outflow compress the surrounding gas inducing star formation. Our results highlight the possible double role of galaxy-wide outflows in host galaxy evolution. This is also supported by recent observations in the local Universe indicate that massive galactic outflows may ignite star formation within the outflow itself. We also present new ALMA observations of a sample of quasars at z∼6 optimised to investigate the extended emission associated with outflows as traced by the [CII]158μm line. Although strong and powerful AGN-driven outflows are expected at these redshifts, our analysis suggests that such outflows may not be as effective as expected in removing gas out of their host galaxies.

Outflows and SF in QSO

The origin and life-cycle of molecular clouds are still poorly constrained, despite their importance for understanding the evolution of the interstellar medium. We have carried out a systematic, homogeneous, spectroscopic survey of the inner Galactic plane, in order to complement the many continuum Galactic surveys available with crucial distance and gas-kinematic information. Our aim is to combine this data set with recent infrared to sub-millimetre surveys at similar angular resolutions. The SEDIGISM survey covers 78 deg^2 of the inner Galaxy (-60 deg < l < +18 deg, |b| < 0.5 deg) in the J=2-1 rotational transition of 13CO. This isotopologue of CO is less abundant than 12CO by factors up to 100. Therefore, its emission has low to moderate optical depths, and higher critical density, making it an ideal tracer of the cold, dense interstellar medium. The data have been observed with the SHFI single-pixel instrument at APEX. The observational setup covers the 13CO(2-1) and C18O(2-1) lines, plus several transitions from other molecules. The observations have been completed. Data reduction is in progress, and the final data products will be made available in the near future. Here we give a detailed description of the survey and the dedicated data reduction pipeline. Preliminary results based on a science demonstration field covering -20 deg < l < -18.5 deg are presented. Analysis of the 13CO(2-1) data in this field reveals compact clumps, diffuse clouds, and filamentary structures at a range of heliocentric distances. By combining our data with data in the (1-0) transition of CO isotopologues from the ThrUMMS survey, we are able to compute a 3D realization of the excitation temperature and optical depth in the interstellar medium. Ultimately, this survey will provide a detailed, global view of the inner Galactic interstellar medium at an unprecedented angular resolution of ~30"., 30 pages. Accepted for publication in A&A. Abstract slightly shortened due to arXiv requirements

Hi-GAL is a large-scale survey of the Galactic plane, performed with Herschel in five infrared continuum bands between 70 and 500 $��$m. We present a band-merged catalogue of spatially matched sources and their properties derived from fits to the spectral energy distributions (SEDs) and heliocentric distances, based on the photometric catalogs presented in Molinari et al. (2016a), covering the portion of Galactic plane $-71.0^{\circ}< \ell < 67.0^{\circ}$. The band-merged catalogue contains 100922 sources with a regular SED, 24584 of which show a 70 $��$m counterpart and are thus considered proto-stellar, while the remainder are considered starless. Thanks to this huge number of sources, we are able to carry out a preliminary analysis of early stages of star formation, identifying the conditions that characterise different evolutionary phases on a statistically significant basis. We calculate surface densities to investigate the gravitational stability of clumps and their potential to form massive stars. We also explore evolutionary status metrics such as the dust temperature, luminosity and bolometric temperature, finding that these are higher in proto-stellar sources compared to pre-stellar ones. The surface density of sources follows an increasing trend as they evolve from pre-stellar to proto-stellar, but then it is found to decrease again in the majority of the most evolved clumps. Finally, we study the physical parameters of sources with respect to Galactic longitude and the association with spiral arms, finding only minor or no differences between the average evolutionary status of sources in the fourth and first Galactic quadrants, or between "on-arm" and "inter-arm" positions., Accepted by MNRAS

The early evolution of massive cluster progenitors is poorly understood. We investigate the fragmentation properties from 0.3 pc to 0.06 pc scales of a homogenous sample of infrared-quiet massive clumps within 4.5 kpc selected from the ATLASGAL survey. Using the ALMA 7 m array we detect compact dust continuum emission towards all targets and find that fragmentation, at these scales, is limited. The mass distribution of the fragments uncovers a large fraction of cores above 40 M⊙, corresponding to massive dense cores (MDCs) with masses up to ~400 M⊙. Seventy-seven percent of the clumps contain at most 3 MDCs per clump, and we also reveal single clumps/MDCs. The most massive cores are formed within the more massive clumps and a high concentration of mass on small scales reveals a high core formation efficiency. The mass of MDCs highly exceeds the local thermal Jeans mass, and we lack the observational evidence of a sufficiently high level of turbulence or strong enough magnetic fields to keep the most massive MDCs in equilibrium. If already collapsing, the observed fragmentation properties with a high core formation efficiency are consistent with the collapse setting in at parsec scales.

We discuss the science drivers for ALMA Band 2 which spans the frequency range from 67 to 90 GHz. The key science in this frequency range are the study of the deuterated molecules in cold, dense, quiescent gas and the study of redshifted emission from galaxies in CO and other species. However, Band 2 has a range of other applications which are also presented. The science enabled by a single receiver system which would combine ALMA Bands 2 and 3 covering the frequency range 67 to 116 GHz, as well as the possible doubling of the IF bandwidth of ALMA to 16 GHz, are also considered., Comment: 27 pages, Report submitted to ESO; 3rd version includes updates to the Band 2+3 science, including adding a new section on observations of variable solar system objects

Theoretical models of grain growth predict dust properties to change as a function of protoplanetary disk radius, mass, age and other physical conditions. We lay down the methodology for a multi-wavelength analysis of (sub-)mm and cm continuum interferometric observations to constrain self-consistently the disk structure and the radial variation of the dust properties. The computational architecture is massively parallel and highly modular. The analysis is based on the simultaneous fit in the uv-plane of observations at several wavelengths with a model for the disk thermal emission and for the dust opacity. The observed flux density at the different wavelengths is fitted by posing constraints on the disk structure and on the radial variation of the grain size distribution. We apply the analysis to observations of three protoplanetary disks (AS 209, FT Tau, DR Tau) for which a combination of spatially resolved observations in the range ~0.88mm to ~10mm is available (from SMA, CARMA, and VLA), finding evidence of a decreasing maximum dust grain size (a_max) with radius. We derive large a_max values up to 1 cm in the inner disk between 15 and 30 AU and smaller grains with a_max~1 mm in the outer disk (R > 80AU). In this paper we develop a multi-wavelength analysis that will allow this missing quantity to be constrained for statistically relevant samples of disks and to investigate possible correlations with disk or stellar parameters.

(Abridged) We present the first public release of high-quality data products (DR1) from Hi-GAL, the {\em Herschel} infrared Galactic Plane Survey. Hi-GAL is the keystone of a suite of continuum Galactic Plane surveys from the near-IR to the radio, and covers five wavebands at 70, 160, 250, 350 and 500 micron, encompassing the peak of the spectral energy distribution of cold dust for 8 < T < 50K. This first Hi-GAL data release covers the inner Milky Way in the longitude range 68�� > l > -70�� in a |b, Astronomy & Astrophysics, accepted

The origin of massive stars is a fundamental open issue in modern astrophysics. Pre-ALMA interferometric studies reveal precursors to early B to late O type stars with collapsing envelopes of 15-20 M$_\odot$ on 1000-3000 AU size-scales. To search for more massive envelopes we selected the most massive nearby young clumps from the ATLASGAL survey to study their protostellar content with ALMA. Our first results using the intermediate scales revealed by the ALMA ACA array providing 3-5" angular resolution, corresponding to $\sim$0.05-0.1 pc size-scales, reveals a sample of compact objects. These massive dense cores are on average two-times more massive than previous studies of similar types of objects. We expect that once the full survey is completed, it will provide a comprehensive view on the origin of the most massive stars., Comment: 4 pages, 1 figure, to appear in proceedings of The 6th Zermatt ISM Symposium: Conditions and Impact of Star Formation From Lab to Space, eds. R. Simon, M. Rollig

We present new VLT/X-Shooter optical and NIR spectra of a sample of 17 candidate young low-mass stars and BDs in the rho-Ophiucus cluster. We derived SpT and Av for all the targets, and then we determined their physical parameters. All the objects but one have M*, accepted for publication in Astronomy & Astrophysics. Abstract shortened to fit arXiv constraints

The first steps toward planet formation involve the coagulation of small microscopic grains into larger and larger pebbles and rocks in gas-rich disks around young stars and brown dwarfs. Observations in the sub-millimeter can trace mm/cm-sized pebbles in the outer disks, and investigate the mechanisms of coagulation/fragmentation and radial migration of these solids. These represent key, yet not fully understood ingredients for our understanding of the formation of planetesimals, the building blocks of planets. Here we present the first results from an observational program using the ALMA and CARMA sub-mm/mm interferometers aimed at characterizing the dust properties and disk structure of young disks around brown dwarfs and very low mass stars. Given the physical conditions expected for these disks, they represent critical test beds for the models of the early stages of planet formation in proto-planetary disks., Comment: 5 pages, 3 figures, proceedings for the conference 'Brown dwarfs come of age', May 20-24 2013, to be published in Memorie della Societa Astronomica Italiana

Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin and evolution. In particular, the relationship between the mass distribution of these clumps (also known as the "clump mass function", or CMF) and the stellar initial mass function (IMF), is still poorly understood. In order to discern the "true" shape of the CMF and to better understand how the CMF may evolve toward the IMF, large samples of bona-fide pre- and proto-stellar clumps are required. The sensitive observations of the Herschel Space Observatory (HSO) are now allowing us to look at large clump populations in various clouds with different physical conditions. We analyse two fields in the Galactic plane mapped by HSO during its science demonstration phase, as part of the more complete and unbiased Herschel infrared GALactic Plane Survey (Hi-GAL). These fields undergo a source-extraction and flux-estimation pipeline, which allows us to obtain a sample with thousands of clumps. Starless and proto-stellar clumps are separated using both color and positional criteria to find those coincident with MIPS 24 micron sources. We describe the probability density functions of the power-law and lognormal models that are used to fit the CMFs, and we then find their best-fit parameters. For the lognormal model we apply several statistical techniques to the data and compare their results. The CMFs of the two SDP fields show very similar shapes, but very different mass scales. This similarity is confirmed by the values of the best-fit parameters of either the power-law or lognormal model. The power-law model leads to almost identical CMF slopes, whereas the lognormal model shows that the CMFs have similar widths. The similar CMF shape but different mass scale represents an evidence that the overall process of star formation in the two regions is very different., Comment: This article is composed of 14 pages, 5 figures and is based on Hi-GAL data. Submitted for publication to Astronomy & Astrophysics on 19 sept. 2012

Contains fulltext : 103694.pdf (Publisher’s version ) (Open Access)

We present Spitzer Space Telescope IRAC and MIPS observations toward a sample of nine high-mass star forming regions at a distance of around 2 kpc. Based on IRAC and MIPS 24 $\mu$m photometric results and 2MASS JHKs data, we carry out a census of young stellar objects (YSOs) in a 5' by 5' field toward each region. Toward seven out of the nine regions, we detect parsec sized clusters with around 20 YSOs surrounded by a more extended and sparse distribution of young stars and protostars. For the other two regions, IRAS 20126+4104 and IRAS 22172+5549, the former has the lowest number of YSOs in the sample and shows no obvious cluster, and the latter appears to be part of a larger, potentially more evolved cluster. The deep IRAC imaging reveals at least twelve outflows in eight out of the nine regions, with nine outflows prominent in the 4.5 $\mu$m band most probably attributed to shocked H$_2$ emission, two outflows dominated by scattered light in the 3.6 and 4.5 $\mu$m bands, and one outflow standing out from its hydrocarbon emission in the 8.0 $\mu$m band. In comparison with previous ground-based observations, our IRAC observations reveal new outflow structures in five regions. The dramatically different morphologies of detected outflows can be tentatively interpreted in terms of possible evolution of massive outflows. The driving sources of these outflows are deeply embedded in dense dusty cores revealed by previous millimeter interferometric observations. We detect infrared counterparts of these dusty cores in the IRAC or MIPS 24 $\mu$m bands. Reflection nebulae dominated by the emission from UV heated hydrocarbons in the 8 $\mu$m band can be found in most regions and they may imply the presence of young B stars., Comment: 76 pages, 25 figures and 5 tables, ApJ in press, a full resolution version available at http://www.cfa.harvard.edu/~kqiu/spitzer.pdf

We have carried out observations at millimeter and centimeter wavelengths towards VV Ser using the Plateau de Bure Interferometer and the Very Large Array. This allows us to compute the SED from near infrared to centimeter wavelengths. The modeling of the full SED has provided insight into the dust properties and a more accurate value of the disk mass. The mass of dust in the disk around VV Ser is found to be about 4 10^(-5) Msun, i.e. 400 times larger than previous estimates. Moreoever, the SED can only be accounted for assuming dust stratification in the vertical direction across the disk. The existence of small grains (0.25--1 micron) in the disk surface is required to explain the emission at near- and mid-infrared wavelengths. The fluxes measured at millimeter wavelengths imply that the dust grains in the midplane have grown up to very large sizes, at least to some centimeters., Comment: To appear in ApJ

We review the properties of dust in protoplanetary disks around optically visible pre-main-sequence stars obtained with a variety of observational techniques, from measurements of scattered light at visual and infrared wavelengths to mid-infrared spectroscopy and millimeter interferometry. A general result is that grains in disks are on average much larger than in the diffuse interstellar medium (ISM). In many disks, there is evidence that a large mass of dust is in grains with millimeter and centimeter sizes, more similar to "sand and pebbles" than to grains. Smaller grains (with micrometer sizes) exist closer to the disk surface, which also contains much smaller particles, e.g., polycyclic aromatic hydrocarbons. There is some evidence of a vertical stratification, with smaller grains closer to the surface. Another difference with ISM is the higher fraction of crystalline relative to amorphous silicates found in disk surfaces. There is a large scatter in dust properties among different sources, but no evidence of correlation with the stellar properties, for samples that include objects from intermediate to solar mass stars and brown dwarfs. There is also no apparent correlation with the age of the central object, over a range roughly between 1 and 10 m.y. This suggests a scenario in which significant grain processing may occur very early in the disk evolution, possibly when it is accreting matter from the parental molecular core. Further evolution may occur, but not necessarily rapidly, since we have evidence that large amounts of grains, from micrometer to centimeter size, can survive for periods as long as 10 m.y.

We review the properties of dust in protoplanetary disks around optically visible pre-main sequence stars obtained with a variety of observational techniques, from measurements of scattered light at visual and infrared wavelengths to mid-infrared spectroscopy and millimeter interferometry. A general result is that grains in disks are on average much larger than in the diffuse interstellar medium (ISM). In many disks, there is evidence that a large mass of dust is in grains with millimeter and centimeter sizes, more similar to "sand and pebbles" than to grains. Smaller grains (with micron-sizes) exist closer to the disk surface, which also contains much smaller particles, e.g., polycyclic aromatic hydrocarbons. There is some evidence of a vertical stratification, with smaller grains closer to the surface. Another difference with ISM is the higher fraction of crystalline relative to amorphous silicates found in disk surfaces. There is a large scatter in dust properties among different sources, but no evidence of correlation with the stellar properties, for samples that include objects from intermediate to solar mass stars and brown dwarfs. There is also no apparent correlation with the age of the central object, over a range roughly between 1 and 10 Myr. This suggests a scenario where significant grain processing may occur very early in the disk evolution, possibly when it is accreting matter from the parental molecular core. Further evolution may occur, but not necessarily rapidly, since we have evidence that large amounts of grains, from micron to centimeter size, can survive for periods as long as 10 Myr., Comment: Protostars and Planets V in press, 16 pages, 7 figures

The young stellar object MWC 297 has been observed with the VLT interferometer equipped with the AMBER instrument. MWC 297 has been spatially resolved in the continuum with a visibility of 0.50 as well as in the Br gamma emission line where the visibility decrease to a lower value of 0.33. This change in the visibility with the wavelength can be interpreted by the presence of an optically thick disk responsible for the visibility in the continuum and of a stellar wind traced by Br gamma and whose apparent size is 40% larger. We validate this interpretation by building a model of the stellar environment that combines a geometrically thin, optically thick accretion disk model consisting of gas and dust, and a latitude-dependent stellar wind outflowing above the disk surface. The continuum emission and visibilities obtained from this model are fully consistent with the interferometric AMBER data. They agree also with existing optical, near-infrared spectra and other broad-band near-infrared interferometric visibilities. A picture emerges in which MWC 297 is surrounded by an equatorial flat disk that is possibly still accreting and an outflowing wind which has a much higher velocity in the polar region than at the equator. [abridged], Comment: 13 pages; to be published in A&A; Acceptance day: 11/10/2005

A near- and mid-infrared study of the star formation complex G9.62+0.19 is presented. It includes photometrically calibrated images through wide-band JHK and narrow-band Brgamma , H2 and 12.5 mu m filters. These were taken at Las Campanas, La Silla and OAN-San Pedro Mártir. We found evidence of two embedded young clusters of O-B5 stars associated with the radio components B and C, one compact and one ultracompact HII region. The data suggest the presence of a third, more dispersed cluster of more luminous infrared stars at the southern edge of the cloud complex. A large fraction of the star members of each cluster exhibit significant infrared excess. We confirm the detection of a very red near- and mid-infrared source immersed in the molecular hot core (component F). An H2 shocked gas knot, probably an obscured Herbig-Haro object, was found associated to the blue-shifted lobe of the high-velocity molecular outflow in this core. The properties of the individual sources are discussed in detail. Partly based on observations collected at the European Southern Observatory, La Silla, at the Las Campanas Observatory, Chile and at the Observatorio Astronómico Nacional, San Pedro Mártir, Mexico

We used the Owens Valley Millimeter Array and the Very Large Array to obtain interferometric maps at millimeter and centimeter wavelengths in both the continuum and various lines [HCO+ (1-0), H13CO+ (1-0), SiO (v=0, J=2-1) and H13CN (1-0)] toward a sample of 11 high-mass protostellar candidates. These sources are known from a previous study to be associated with dense gas and dust and to not be associated with H II regions. All 11 sources were detected in HCO+ (1-0), nine in the millimeter continuum and five (of eight observed) in the centimeter continuum. The derived physical parameters confirm the high-mass nature of these molecular clumps and suggest they are gravitationally bound. Molecular outflows were detected toward six sources, with flow masses and momenta much higher than in low-mass young stellar objects. In many of the sources the molecular emission is organized in substructures, resolved both spatially and in velocity. We find that the sources may be characterized by their degree of fragmentation, turbulence, and outflow activity, with the sample dividing into two groups: group 1 cores have multiple peaks but with a clearly dominant component and larger line widths and are systematically associated with outflows, while group 2 cores have several comparable subentities, smaller line widths, and no association with outflows. We speculate that more massive cores may form from smaller cores via coalescence or competitive accretion. Even conservative estimates of outflow mass-loss rates, however, indicate that accretion is the dominant process in the later formation of massive protostars from such cores. We find a flattening of the outflow mass spectra with increasing flow velocities, at variance with previous studies that suggest a steepening with increasing flow velocities. In the light of this result we suggest a reevaluation of the wide-angle wind momentum-driven flow models to describe the acceleration of outflows in the earliest stages of massive star formation.

This paper discusses evidence for and properties of disks associated to brown dwarfs in the star-forming region rho Oph. We selected nine objects from the ISOCAM survey of Bontemps et al. (\cite{Bonea01}) that have detections in the two mid-infrared bands (6.7 and 14.3 mu m), relatively low extinction and low luminosity. We present low-resolution near-infrared spectra in the J, H and K bands, and determine for each source spectral type, extinction, effective temperature and luminosity by comparing the spectra to those of field dwarfs and to the most recent model stellar atmospheres. The results indicate that eight objects have spectral types M6-M7.5, effective temperature of 2600-2700 K, one has a later spectral type (M8.5) and lower temperature (about 2400 K). The derived extinctions range between AV ~ 2 and 8 mag. The location of the objects on the HR diagram, in spite of the uncertainties of the evolutionary tracks for young objects of substellar mass, indicates that all the objects are very young and have masses below about 0.08 Msun. The coolest object in our sample has mass in the range 8-12 MJ (0.008-0.012 Msun). In all cases, the mid-infrared excess is consistent with the predictions of models of disks irradiated by the central object, showing that circumstellar disks are commonly associated to young brown dwarfs and planetary-mass objects. Finally, we discuss possible variations of the disk geometry among different objects, as well as the possibility of using these data to discriminate between various formation scenarios. Partly based on observations collected at the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, and at the European Southern Observatory, La Silla and Paranal, Chile.

We present a complete low-resolution (R~100) near-IR spectrum of the substellar object GY11, a member of the ? Ophiuchi young association. The object is remarkable because of its low estimated mass and age and because it is associated with a mid-IR source, an indication of a surrounding dusty disk. Based on the comparison of our spectrum with similar spectra of field M dwarfs and atmospheric models, we obtain revised estimates of the spectral type, effective temperature, and luminosity of the central object. These parameters are used to place the object on a H-R diagram and to compare it with the predictions of pre-main-sequence evolutionary models. Our analysis suggests that the central object has a very low mass, probably below the deuterium-burning limit and in the range of 8-12 MJ, and a young age of less than 1 Myr. The IR excess is shown to be consistent with the emission of a flared, irradiated disk similar to those found in more massive brown dwarf and T Tauri systems. This result suggests that substellar objects, even the so-called isolated planetary mass objects, found in young stellar associations are produced in a similar fashion as stars, by core contraction and gravitational collapse.

This paper discusses evidence for and properties of disks associated to brown dwarfs in the star-forming region rho-Oph. We selected nine objects fr om the ISOCAM survey of Bontemps et al. (2001) that have detections in the two mid-infrared bands (6.7 and 14.3 um), relatively low extinction and low luminosity. We present low-resolution near-infrared spectra in the J, H and K bands, and determine for each source spectral type, extinction, effective temperature a nd luminosity by comparing the spectra to those of field dwarfs and to the most recent model stellar atmospheres. The results indicate that eight objects have spectral types M6-M7.5, effective temperature of 2600-2700 K, one has a later spectral type (M8.5) and lower temperature (about 2400 K). The derived extinctions range between Av~2 and 8 mag. The location of the objects on the HR diagram, in spite of the uncertainties of the evolutionary tracks for young objects of substellar mass, indicates that all the objects are very young and have masses below about 0.08 Msun. The coolest object in our sample has mass in the range 8-12 Mjup (0.008-0.012 Msun). In all cases, the mid-infrared excess is consistent with the predictions of mode ls of disks irradiated by the central object, showing that circumstellar disks are commonly associated to young brown dwarfs and plan etary-mass objects. Finally, we discuss possible variations of the disk geometry among different objects, as well as the possibility of using these data to discriminate between various f ormation scenarios., Comment: 15 pages, A&A in press, full resolution color figures for appendix A and B are available at http://www.arcetri.astro.it/~lt/preprints/preprints.html

We report J, H and K photometry of 86 stars in 40 fields in the northern hemisphere. The fields are smaller than or comparable to a 4x4 arcmin field-of-view, and are roughly uniformly distributed over the sky, making them suitable for a homogeneous broadband calibration network for near-infrared panoramic detectors. K magnitudes range from 8.5 to 14, and J-K colors from -0.1 to 1.2. The photometry is derived from a total of 3899 reduced images; each star has been measured, on average, 26.0 times per filter on 5.5 nights. Typical errors on the photometry are about 0.012., Comment: 10 pages including 3 figures, one separate figure on four pages. The finding chart of the AS-30 field and a few coordinates have been corrected. GIF finding charts can also be found at http://www.arcetri.astro.it/~hunt/std.html

We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2 . From our molecular hydrogen data, we conclude that densities are moderate (3-6 10^4 cm^-3) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicular to the ionization front which penetrates into the neutral gas. We have used the 1.317um OI line to estimate the FUV radiation field incident at the ionization front and find values of 1-3x10^4 greater than the average interstellar field. From [FeII] line measurements, we conclude that the electron density in the ionized layer associated with the ionization front is of order 10^4 cm^-3. Finally, our analysis of the helium and hydrogen recombination lines implies essential coincidence of the helium and hydrogen Stromgren spheres., Comment: 17 pages with 17 figures included. Accepted for publication by Astronomy and Astrophysics

Molecular complexity builds up at each step of the Sun-like star formation process, starting from simple molecules and ending up in large polyatomic species. Complex organic molecules (COMs; such as methyl formate, HCOOCH$_3$, dymethyl ether, CH$_3$OCH$_3$, formamide, NH$_2$CHO, or glycoaldehyde, HCOCH$_2$OH) are formed in all the components of the star formation recipe (e.g. pre-stellar cores, hot-corinos, circumstellar disks, shocks induced by fast jets), due to ice grain mantle sublimation or sputtering as well as gas-phase reactions. Understanding in great detail the involved processes is likely the only way to predict the ultimate molecular complexity reached in the ISM, as the detection of large molecules is increasingly more difficult with the increase of the number of atoms constituting them. Thanks to the recent spectacular progress of astronomical observations, due to the Herschel (sub-mm and IR), IRAM and SMA (mm and sub-mm), and NRAO (cm) telescopes, an enormous activity is being developed in the field of Astrochemistry, extending from astronomical observatories to chemical laboratories. We are involved in several observational projects providing unbiased spectral surveys (in the 80-300 and 500-2000 GHz ranges) with unprecedented sensitivity of templates of dense cores and protostars. Forests of COM lines have been detected. In this chapter we will focus on the chemistry of both cold prestellar cores and hot shocked regions, (i) reviewing results and open questions provided by mm-FIR observations, and (ii) showing the need of carrying on the observations of COMs at lower frequencies, where SKA will operate. We will also emphasize the importance of analysing the spectra by the light of the experimental studies performed by our team, who is investigating the chemical effects induced by ionising radiation bombarding astrophysically relevant ices., Comment: 18 pages, 8 figures

The Advanced Telescope for High ENergy Astrophysics (Athena) is the X-ray observatory mission selected by ESA within its Cosmic Vision 2015-2025 programme to address the Hot and Energetic Universe scientific theme. The ESO-Athena Synergy Team (EAST) has been tasked to single out the potential scientific synergies between Athena and optical/near-infrared (NIR) and sub/mm ground based facilities, in particular those of ESO (i.e., the VLT and ELT, ALMA and APEX), by producing a White Paper to identify and develop the: 1. needs to access ESO ground-based facilities to achieve the formulated Athena science objectives; 2. needs to access Athena to achieve the formulated science objectives of ESO facilities contemporary to Athena; 3. science areas where the synergetic use of Athena and ESO facilities in the late 2020s will result in scientific added value. Community input to the process happened primarily via a dedicated ESO - Athena Synergy Workshop that took place on Sept. 14 - 16, 2016 at ESO, Garching. This White Paper presents the results of the EAST's work, sorted by synergy area, and deals with the following topics: 1. the Hot Universe: Early groups and clusters and their evolution, Physics of the Intracluster medium, Missing baryons in cosmic filaments; 2. the Energetic Universe: Supermassive black hole (SMBH) history, SMBH accretion disks, Active Galactic Nuclei feedback - Molecular outflows, Ultra-fast outflows, Accretion Physics, Transient Science; 3. Observatory Science: Star Formation, Stars. It then discusses the optical-NIR-sub-mm perspective by providing details on VLT/MOONS, the E-ELT instruments, in particular the MOS, VISTA/4MOST, the ESO and ALMA archives, future ALMA and ESO developments, and finally the (likely) ESO - Athena astronomical scene in the 2020s. (abridged), Comment: 70 pages, 16 figures

International audience; Not Available

Using the Owens Valley and Nobeyama Radio Observatory interferometers, we carried out an unbiased search for hot molecular cores and ultracompact UC HII regions toward the high-mass star forming region G19.61--0.23. In addition, we performed 1.2 mm imaging with SIMBA, and retrieved 3.5 and 2 cm images from the VLA archive data base. The newly obtained 3 mm image brings information on a cluster of high-mass (proto)stars located in the innermost and densest part of the parsec scale clump detected in the 1.2 mm continuum. We identify a total of 10 high-mass young stellar objects: one hot core (HC) and 9 UC HII regions, whose physical parameters are obtained from model fits to their continuum spectra. The ratio between the current and expected final radii of the UC \HII regions ranges from 0.3 to 0.9, which leaves the possibility that all O-B stars formed simultaneously. Under the opposite assumption -- namely that star formation occurred randomly -- we estimate that HC lifetime is less than $\sim$1/3 of that of UCHII regions on the basis of the source number ratio between them., Comment: 13 pages, 2 figs, including a color fig

We utilize ALMA archival data to estimate the dust disk size of 152 protoplanetary disks in Lupus (1-3 Myr), Chamaeleon I (2-3 Myr), and Upper-Sco (5-11 Myr). We combine our sample with 47 disks from Tau/Aur and Oph whose dust disk radii were estimated, as here, through fitting radial profile models to visibility data. We use these 199 homogeneously derived disk sizes to identify empirical disk-disk and disk-host property relations as well as to search for evolutionary trends. In agreement with previous studies, we find that dust disk sizes and millimeter luminosities are correlated, but show for the first time that the relationship is not universal between regions. We find that disks in the 2-3 Myr-old Cha I are not smaller than disks in other regions of similar age, and confirm the Barenfeld et al. (2017) finding that the 5-10 Myr USco disks are smaller than disks belonging to younger regions. Finally, we find that the outer edge of the Solar System, as defined by the Kuiper Belt, is consistent with a population of dust disk sizes which have not experienced significant truncation.

We present the first high-resolution sub-mm survey of both dust and gas for a large population of protoplanetary disks. Characterizing fundamental properties of protoplanetary disks on a statistical level is critical to understanding how disks evolve into the diverse exoplanet population. We use ALMA to survey 89 protoplanetary disks around stars with $M_{\ast}>0.1~M_{\odot}$ in the young (1--3~Myr), nearby (150--200~pc) Lupus complex. Our observations cover the 890~$\mu$m continuum and the $^{13}$CO and C$^{18}$O 3--2 lines. We use the sub-mm continuum to constrain $M_{\rm dust}$ to a few Martian masses (0.2--0.4~$M_{\oplus}$) and the CO isotopologue lines to constrain $M_{\rm gas}$ to roughly a Jupiter mass (assuming ISM-like $\rm {[CO]/[H_2]}$ abundance). Of 89 sources, we detect 62 in continuum, 36 in $^{13}$CO, and 11 in C$^{18}$O at $>3\sigma$ significance. Stacking individually undetected sources limits their average dust mass to $\lesssim6$ Lunar masses (0.03~$M_{\oplus}$), indicating rapid evolution once disk clearing begins. We find a positive correlation between $M_{\rm dust}$ and $M_{\ast}$, and present the first evidence for a positive correlation between $M_{\rm gas}$ and $M_{\ast}$, which may explain the dependence of giant planet frequency on host star mass. The mean dust mass in Lupus is 3$\times$ higher than in Upper Sco, while the dust mass distributions in Lupus and Taurus are statistically indistinguishable. Most detected disks have $M_{\rm gas}\lesssim1~M_{\rm Jup}$ and gas-to-dust ratios $