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A search for clustering around Herbig Ae/Be stars - II. Atlas of the observed sources

We present large field infrared images of a sample of 45 Herbig Ae/Be stars. Stellar parameters, such as age and luminosity, have been derived for all of them in a consistent way. The images have been used to identify stellar groups or clusters associated with the Herbig Ae/Be star. The results presented in this paper form the database for a study of clustering around...

Near-infrared images of star forming regions containing masers - Las Campanas observations of 31 southern sources

We present sensitive high resolution near infrared (NIR) broad band (J, H, and K) observations of a sample of 31 Star Forming Regions (SFRs) which contain H2O and OH maser sources. The observations are aimed at the detection and characterization of Young Stellar Objects (YSOs) which may be the source of excitation of the maser emission. In spite of the large number of sources...

Near-infrared images of star forming regions containing masers - Las Campanas observations of 31 southern sources

We present sensitive high resolution near infrared (NIR) broad band (J, H, and K) observations of a sample of 31 Star Forming Regions (SFRs) which contain H2O and OH maser sources. The observations are aimed at the detection and characterization of Young Stellar Objects (YSOs) which may be the source of excitation of the maser emission. In spite of the large number of sources...

ALMA continuum observations of the protoplanetary disk AS 209 - Evidence of multiple gaps opened by a single planet

This paper presents new high angular resolution ALMA 1.3 mm dust continuum observations of the protoplanetary system AS 209 in the Ophiuchus star forming region. The dust continuum emission is characterized by a main central core and two prominent rings at r = 75 au and r = 130 au intervaled by two gaps at r = 62 au and r = 103 au. The two gaps have different widths and depths...

Dust and gas environment of the young embedded cluster IRAS 18511+0146

Context. Since massive and intermediate mass stars form in clusters, a comparative investigation of the environments of the young embedded cluster members can reveal significant information about the conditions under which stars form and evolve.Aims. IRAS 18511+0146 is a young embedded (proto)cluster located at 3.5 kpc surrounding what appears to be an intermediate mass protostar...

ALMA survey of massive cluster progenitors from ATLASGAL - Limited fragmentation at the early evolutionary stage of massive clumps

S. Leurini S. Longmore A. Palau N. Peretto F. Schuller J. C. Tan L. Testi A. Traficante J. S. Urquhart The early evolution of massive cluster progenitors is poorly understood. We investigate the

The Pillars of Creation revisited with MUSE: gas kinematics and high-mass stellar feedback traced by optical spectroscopy

Integral field unit (IFU) data of the iconic Pillars of Creation in M16 are presented. The ionization structure of the pillars was studied in great detail over almost the entire visible wavelength range, and maps of the relevant physical parameters, e.g. extinction, electron density, electron temperature, line-of-sight velocity of the ionized and neutral gas are shown. In...

Old pre-main-sequence stars - Disc reformation by Bondi-Hoyle accretion

Young stars show evidence of accretion discs which evolve quickly and disperse with an e-folding time of ~3 Myr. This is in striking contrast with recent observations that suggest evidence of numerous >30 Myr old stars with an accretion disc in large star-forming complexes. We consider whether these observations of apparently old accretors could be explained by invoking Bondi...

Old pre-main-sequence stars - Disc reformation by Bondi-Hoyle accretion

Young stars show evidence of accretion discs which evolve quickly and disperse with an e-folding time of ~3 Myr. This is in striking contrast with recent observations that suggest evidence of numerous >30 Myr old stars with an accretion disc in large star-forming complexes. We consider whether these observations of apparently old accretors could be explained by invoking Bondi...

Chasing discs around O-type (proto)stars: Evidence from ALMA observations

R. Galván-Madrid C. Goddi T. Henning M. G. Hoare P. D. Klaassen R. Kuiper M. S. N. Kumar S. Lumsden T. Peters V. M. Rivilla P. Schilke L. Testi F. van der Tak S. Vig C. M. Walmsley H. Zinnecker

The sulfur depletion problem: upper limits on the H2S2, HS·2, and S2 gas-phase abundances toward the low-mass warm core IRAS 16293-2422

Context. A fraction of the missing sulfur in dense clouds and circumstellar regions could be in the form of three species not yet detected in the interstellar medium: H2S2, HS.2, and S2 according to experimental simulations performed under astrophysically relevant conditions. These S-S bonded molecules can be formed by the energetic processing of H2S-bearing ice mantles on dust...

Evidence for a correlation between mass accretion rates onto young stars and the mass of their protoplanetary disks

A&A Astronomy & Astrophysics Letter to the Editor C. F. Manara 3 G. Rosotti 1 L. Testi 0 6 7 A. Natta 5 7 J. M. Alcalá 4 J. P. Williams 9 M. Ansdell 9 A. Miotello 8 N. van der Marel 8 9 M. Tazzari

Evidence for a correlation between mass accretion rates onto young stars and the mass of their protoplanetary disks

A&A Astronomy & Astrophysics Letter to the Editor C. F. Manara 3 G. Rosotti 1 L. Testi 0 6 7 A. Natta 5 7 J. M. Alcalá 4 J. P. Williams 9 M. Ansdell 9 A. Miotello 8 N. van der Marel 8 9 M. Tazzari

Constraints on the radial distribution of the dust properties in the CQ Tauri protoplanetary disk

Edition (New York: Cambridge University Press) Ricci , L. , Testi , L. , Natta , A. , et al. 2010a, A &A, 512 , 15 Ricci , L. , Testi , L. , Natta , A. , & Brooks , K. J. 2010b , A &A, 521 , 66 Ricci , L

Looking for outflow and infall signatures in high-mass star-forming regions

Context. Many physical parameters change with time in star-forming regions. Here we attempt to correlate changes in the infall and outflow motions in high-mass star-forming regions with evolutionary stage using JCMT observations. Aims. From a sample of 45 high-mass star-forming regions in three phases of evolution, we investigate the presence of established infall and outflow...

On the shape of the mass-function of dense clumps in the Hi-GAL fields - II. Using Bayesian inference to study the clump mass function

Context. Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin, their evolution, and their detailed physical properties. 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.Aims. To better...

On the shape of the mass-function of dense clumps in the Hi-GAL fields - II. Using Bayesian inference to study the clump mass function

Context. Stars form in dense, dusty clumps of molecular clouds, but little is known about their origin, their evolution, and their detailed physical properties. 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.Aims. To better...

Accurate determination of accretion and photospheric parameters in young stellar objects: The case of two candidate old disks in the Orion Nebula Cluster

Context. Current planet formation models are largely based on the observational constraint that protoplanetary disks have a lifetime of ~3 Myr. Recent studies, however, report the existence of pre-main-sequence stars with signatures of accretion (strictly connected with the presence of circumstellar disks) and photometrically determined ages of 30 Myr or more. Aims. Here, we...

Accurate determination of accretion and photospheric parameters in young stellar objects: The case of two candidate old disks in the Orion Nebula Cluster

Context. Current planet formation models are largely based on the observational constraint that protoplanetary disks have a lifetime of ~3 Myr. Recent studies, however, report the existence of pre-main-sequence stars with signatures of accretion (strictly connected with the presence of circumstellar disks) and photometrically determined ages of 30 Myr or more. Aims. Here, we...