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Context. In spite of decades of theoretical efforts, the physical origin of the stellar initial mass function (IMF) is still a subject of debate. Aims. We aim to gain an understanding of the influence of various physical processes such as radiative stellar feedback, magnetic field, and non-ideal magneto-hydrodynamics on the IMF. Methods. We present a series of numerical simulations of collapsing 1000 M⊙ clumps, taking into account the radiative feedback and magnetic field with spatial resolution down to 1 AU. We performed both ideal and non-ideal MHD runs, and various radiative feedback efficiencies are considered. We also developed analytical models that we confront with the numerical results. Results. We computed the sum of the luminosities produced by the stars in the calculations and it shows a good comparison with the bolometric luminosities reported in observations of massive star-forming clumps. The temperatures, velocities, and densities are also found to be in good agreement with recent observations. The stellar mass spectrum inferred for the simulations is, generally speaking, not strictly universal and it varies, in particular, with magnetic intensity. It is also influenced by the choice of the radiative feedback efficiency. In all simulations, a sharp drop in the stellar distribution is found at about Mmin ≃ 0.1 M⊙, which is likely a consequence of the adiabatic behaviour induced by dust opacities at high densities. As a consequence, when the combination of magnetic and thermal support is not too high, the mass distribution presents a peak located at 0.3–0.5 M⊙. When the magnetic and thermal support are high, the mass distribution is better described by a plateau, that is, dN/dlog M ∝ M−Γ, Γ ≃ 0. At higher masses, the mass distributions drop following power-law behaviours until a maximum mass, Mmax, whose value increases with field intensity and radiative feedback efficiency. Between Mmin and Mmax, the distributions inferred from the simulations are in good agreement with an analytical model inferred from gravo-turbulent theory. Due to the density PDF ∝ρ−3/2 relevant for collapsing clouds, values on the order of Γ ≃ 3/4 are inferred both analytically and numerically. More precisely, after 150 M⊙ of gas have been accreted, the most massive star has a mass of about 8 M⊙ when magnetic field is significant, and 3 M⊙ only when both the radiative feedback efficiency and magnetic field are low, respectively. Conclusions. When both the magnetic field and radiative feedback are taken into account, they are found to have a significant influence on the stellar mass spectrum. In particular, both of these effects effectively reduce fragmentation and lead to the formation of more massive stars.

G351.776-0.527 is among the most massive, closest, and youngest filaments in the inner Galactic plane and therefore it is an ideal laboratory to study the kinematics of dense gas and mass replenishment on a large scale. In this paper, we present far-infrared (FIR) and submillimetre wavelength continuum observations combined with spectroscopic C$^{18}$O (2-1) data of the entire region to study its temperature, mass distribution, and kinematics. The structure is composed of a main elongated region with an aspect ratio of $\sim 23$, which is associated with a network of filamentary structures. The main filament has a remarkably constant width of 0.2 pc. The total mass of the network (including the main filament) is $\geq 2600$ M$_\odot$, while we estimate a mass of $\sim 2000$ M$_\odot$ for the main structure. Therefore, the network harbours a large reservoir of gas and dust that could still be accreted onto the main structure. From the analysis of the gas kinematics, we detect two velocity components in the northern part of the main filament. The data also reveal velocity oscillations in C$^{18}$O along the spine in the main filament and in at least one of the branches. Considering the region as a single structure, we find that it is globally close to virial equilibrium indicating that the entire structure is approximately in a stable state., 18 pages, 19 figures, accepted for publication in A&A

(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{\deg} > l > -70{\deg} in a |b, Comment: Astronomy & Astrophysics, accepted

The aims are to investigate the clustering of the far-infrared sources from the Herschel infrared Galactic Plane Survey (Hi-GAL) in the Galactic longitude range of -71 to 67 deg. These clumps, and their spatial distribution, are an imprint of the original conditions within a molecular cloud. This will produce a catalogue of over-densities. The minimum spanning tree (MST) method was used to identify the over-densities in two dimensions. The catalogue was further refined by folding in heliocentric distances, resulting in more reliable over-densities, which are cluster candidates. We found 1,633 over-densities with more than ten members. Of these, 496 are defined as cluster candidates because of the reliability of the distances, with a further 1,137 potential cluster candidates. The spatial distributions of the cluster candidates are different in the first and fourth quadrants, with all clusters following the spiral structure of the Milky Way. The cluster candidates are fractal. The clump mass functions of the clustered and isolated are statistically indistinguishable from each other and are consistent with Kroupa's initial mass function., Comment: 24 pages, 27 figures