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Aims. Filamentary structures of early type stars are found to be a common feature of the Magellanic Clouds formed at an age of about 0.9-2*10^8 yr. As we go to younger ages these large structures appear fragmented and sooner or later form…

We present ATCA observations of the H2O maser line and radio continuum at 18.0GHz and 22.8GHz, toward a sample of 192 massive star forming regions containing several clumps already imaged at 1.2mm. The main aim of this study is to…

Astrophysics of Galaxies · Physics 2015-06-12 A. Sanchez-Monge , M. T. Beltran , R. Cesaroni , F. Fontani , J. Brand , S. Molinari , L. Testi , M. Burton

We report new results on outflow and infall in the star forming cores W3-SE SMA-1 and SMA-2 based on analysis of $\sim2.5\arcsec$ resolution observations of the molecular lines HCN(3-2), HCO$^+$(3-2), N$_2$H$^+$(3-2) and…

Solar and Stellar Astrophysics · Physics 2015-05-30 Lei Zhu , Jun-Hui Zhao , M. C. H. Wright

Investigating the physical and chemical structures of massive star-forming regions is critical for understanding the formation and the early evolution of massive stars. We performed a detailed line survey toward six dense cores named as…

The formation of hypercompact (HC) HII regions is an important stage in massive star formation. Spectral line and continuum observations can explore its dynamic conditions. We present high angular resolution observations carried out with…

Astrophysics of Galaxies · Physics 2014-09-29 Chuan-Peng Zhang , Jun-Jie Wang , Jin-Long Xu , Friedrich Wyrowski , Karl M. Menten

Rich in HII regions, giant molecular clouds are natural laboratories to study massive stars and sequential star formation. The Galactic star forming complex W33 is located at l=~12.8deg and at a distance of 2.4 kpc, has a size of ~10 pc and…

It is well known that most of the stars form in rich clusters. However, recent $Spitzer$ observations have shown that a significant number of stars also form in distributed mode, origin of which is not well understood. In this work, we aim…

Solar and Stellar Astrophysics · Physics 2019-02-20 Neelam Panwar , Manash R. Samal , A. K. Pandey , H. P . Singh , Saurabh Sharma

We present new high-sensitivity high-resolution mm-wave observations of the Onsala 1 ultra-compact HII region that bring to light the internal structure of this massive star forming cloud. The 1.2 mm continuum map obtained with the IRAM…

Astrophysics · Physics 2009-11-10 M. S. N. Kumar , M. Tafalla , R. Bachiller

We present the first detailed study of the large, ~30 pc diameter, inner-Galaxy HII region W 39. Radio recombination line observations combined with HI absorption spectra and Galactic rotation models show that the region lies at V(LSR) =…

Astrophysics of Galaxies · Physics 2015-06-12 C. R. Kerton , K. Arvidsson , M. J. Alexander

The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary…

Fragmentation and evolution for the molecular shells of the compact HII regions are less explored compared to their evolved counterparts. We map nine compact HII regions with a typical diameter of 0.4 pc that are surrounded by molecular…

We present wide-field near-infrared images of the DR21/W75 high-mass star forming region, obtained with the Wide Field Camera, WFCAM, on the United Kingdom Infrared Telescope. Broad-band JHK and narrow-band H2 1-0S(1) images are compared to…

Astrophysics · Physics 2008-11-26 C. J. Davis , M. S. N. Kumar , G. Sandell , D. Froebrich , M. D. Smith , M. J. Currie

As a work in progress, results from a chemical and physical analysis of molecular cores in early evolutionary stages concerning star formation are presented. Using archival data from the Atacama Large Millimeter Array (ALMA), a sample of 37…

Astrophysics of Galaxies · Physics 2026-03-06 R. D. Taboada , S. Paron , M. E. Ortega , H. Saldaño

In this study, we examine three cluster-forming hub-filament systems (HFS) - W3(OH), W3 Main, and S 106 - spanning evolutionary stages from early to advanced, with a focus on their magnetic field (B-field) structures and filament line-mass…

Astrophysics of Galaxies · Physics 2025-11-12 M. S. N. Kumar , D. Arzoumanian , S. Inutsuka , R. Furuya , N. K. Bhadari

We present an analysis of the molecular and atomic gas emission in the rest-frame far-infrared and sub-millimetre, from the lensed z=2.3 sub-millimetre galaxy SMM J2135-0102. We obtain very high signal-to-noise detections of 11 transitions…

We report molecular line and dust continuum observations, made with the SEST telescope, towards four young high-mass star forming regions associated with highly luminous (L> 6x10^5 Lsun) IRAS sources (15290-5546, 15502-5302, 15567-5236 and…

Astrophysics of Galaxies · Physics 2014-11-20 Guido Garay , Diego Mardones , Leonardo Bronfman , Jorge May , Luis Chavarria , Lars-Ake Nyman

We observed the W51 high-mass star-forming complex with ALMA's longest-baseline configurations, achieving an angular resolution of $\sim$20 milliarcseconds, corresponding to a linear resolution of $\sim$100 au at $D_{\mathrm{W51}}=5.4$ kpc.…

Astrophysics of Galaxies · Physics 2020-12-23 Ciriaco Goddi , Adam Ginsburg , Luke Maud , Qizhou Zhang , Luis Zapata

We present the first high-angular resolution study of the MonR2 star-forming complex carried out with the Submillimeter Array at (sub-)millimeter wavelengths. We image the continuum and molecular line emission toward the young stellar…

Solar and Stellar Astrophysics · Physics 2015-06-24 Marion Dierickx , Izaskun Jimenez-Serra , Victor Rivilla , Qizhou Zhang

We present wide area radio (12 mm) Mopra Telescope observations of the complex and rich massive star forming region G305. Our goals are to determine the reservoir for star formation within G305 using NH3 to trace the dense molecular…

Astrophysics of Galaxies · Physics 2015-05-19 L. Hindson , M. A. Thompson , J. S. Urquhart , J. S. Clark , B. Davies

High-mass stars have generally been assumed to accrete most of their mass while already contracted onto the main sequence, but this hypothesis has not been observationally tested. We present ALMA observations of a 3 x 1.5 pc area in the W51…

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