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We have recently completed an observing program with the Australia Telescope Compact Array towards massive star formation regions traced by 6.7 GHz methanol maser emission. We found the molecular cores could be separated into groups based…

Astrophysics · Physics 2007-11-29 S. N. Longmore , M. G. Burton , C. R. Purcell , P. Barnes , J. Ott

We present results from a study of two luminous IRAS sources thought to be young massive star-forming regions and which have no previously detected radio continuum emission: IRAS 15596-5301 and IRAS 16272-4837. Our study incorporates…

Astrophysics · Physics 2007-05-23 K. J. Brooks , G. Garay , D. Mardones , R. P. Norris , M. G. Burton

Massive star-forming regions exhibit an extremely rich and diverse chemistry, which in principle provides a wealth of molecular probes, as well as laboratories for interstellar prebiotic chemistry. Since the chemical structure of these…

Sometimes the early star formation can be found in cold and dense molecular clouds, such as infrared dark cloud (IRDC). Considering star formation often occurs in clustered condition, HII regions may be triggering a new generation of star…

Astrophysics of Galaxies · Physics 2017-06-07 Chuan-Peng Zhang , Jing-Hua Yuan , Jin-Long Xu , Xiao-Lan Liu , Nai-Ping Yu , Nan Li , Li-Ping He , Guo-Yin Zhang , Jun-Jie Wang

NGC 2903 is a nearby barred spiral with an active starburst in the center and Hii regions distributed along its bar. We aim to analyse the star formation properties in the bar region of NGC 2903 and study the links with the typical bar…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 G. Popping , I. Perez , A. Zurita

Theoretical models suggest that massive stars form via disk-mediated accretion, with bipolar outflows playing a fundamental role. A recent study toward massive molecular outflows has revealed a decrease of the SiO line intensity as the…

Astrophysics of Galaxies · Physics 2015-06-15 A. Sanchez-Monge , A. Lopez-Sepulcre , R. Cesaroni , C. M. Walmsley , C. Codella , M. T. Beltran , M. Pestalozzi , S. Molinari

We report interferometric observations of the high-mass star-forming object IRAS 23033+5951. Our observations reveal two massive molecular cloud cores, designated IRAS 23033+5951-MMS1 and IRAS 23033+5951-MMS2. MMS1 has already formed a…

Astrophysics · Physics 2009-11-13 Michael A. Reid , Brenda C. Matthews

Aims. Studying protostellar objects in their earliest stages, particularly during the Class 0 phase, provides key insight into the beginnings of planet formation and dust evolution. Disentangling the various components, however, is…

Among the tracers of the earliest phases in the massive star formation process, methanol masers have gained increasing importance. The phenomenological distinction between Class I and II methanol masers is based on their spatial association…

Astrophysics of Galaxies · Physics 2015-05-18 F. Fontani , R. Cesaroni , R. S. Furuya

The transition between the proto-star, Class I, and the pre-main sequence star, Class II, phases is still one of the most uncertain, and important, stages in the knowledge of the process of formation of an individual star, because it is the…

Astrophysics of Galaxies · Physics 2015-06-16 O. Morata , Y. J. Kuan , P. T. P. Ho , H. C. Huang , E. A. Magnier , R. Zhao-Geisler

We have searched for massive molecular outflows in a sample of high-mass star forming regions, and we have characterised both the outflow properties and those of their associated molecular clumps. With a sample composed largely of more…

Astrophysics of Galaxies · Physics 2015-05-13 A. Lopez-Sepulcre , C. Codella , R. Cesaroni , N. Marcelino , C. M. Walmsley

We present molecular line observations of the massive star forming region IRAS 17233-3606 aimed at studying the molecular core associated with the source. The observations were made using the Atacama Pathfinder Experiment telescope in the…

Astrophysics · Physics 2009-11-13 S. Leurini , C. Hieret , S. Thorwirth , F. Wyrowski , P. Schilke , K. M. Menten , R. Guesten , L. Zapata

Hot molecular cores (HMCs) are intermediate stages of high-mass star formation and are also known for their rich emission line spectra at (sub-)mm wavebands. The observed spectral feature of HMCs such as total number of emission lines and…

Using the IRAM 30 m telescope, a mapping survey in optically thick and thin lines was performed towards 46 high mass star-forming regions. The sample includes UC H{\sc ii} precursors and UC H{\sc ii} regions. Seventeen sources are found to…

Astrophysics · Physics 2009-11-13 Yuefang Wu , Christian Henkel , Rui Xue , Xin Guan , Martin Miller

We present the results of NH3 (1,1), (2,2) and (3,3) and H2O maser simultaneous mapping observations toward the high-mass star-forming region W33 with the Nobeyama 45-m radio telescope. W33 has six dust clumps and one of which, W33 Main, is…

Embedded clusters like W3 Main are complex and dynamically evolving systems that represent an important phase of the star formation process. We aim at the characterization of the entire stellar content of W3 Main in a statistical sense to…

Astrophysics of Galaxies · Physics 2015-06-17 A. Bik , A. Stolte , M. Gennaro , W. Brandner , D. Gouliermis , B. Hußmann , E. Tognelli , B. Rochau , Th. Henning , A. Adamo , H. Beuther , A. Pasquali , Y. Wang

The evolutionary sequence for high-mass star formation starts with massive starless clumps that go on to form protostellar, young stellar objects and then compact HII regions. While there are many examples of the three later stages, the…

Astrophysics of Galaxies · Physics 2023-05-09 T. G. S. Pillai , J. S. Urquhart , S. Leurini , Q. Zhang , A. Traficante , D. Colombo , K. Wang , L. Gomez , F. Wyrowski

We present new observations of C-band continuum emission and masers to assess high-mass ($>$8 $M_\odot$) star formation at early evolutionary phases in the inner 200 pc of the Central Molecular Zone (CMZ) of the Galaxy. The continuum…

Increasing evidence shows that most stars in the Milky Way, including the Sun, are born in star-forming regions containing also high-mass stars, but due to both observational and theoretical challenges, our comprehension of their chemical…

We analyse C$^{18}$O ($J=3-$2) data from a sample of 99 infrared-bright massive young stellar objects (MYSOs) and compact HII regions that were identified as potential molecular-outflow sources in the Red MSX source (RMS) survey. We extract…

Solar and Stellar Astrophysics · Physics 2015-09-02 L. T. Maud , S. L. Lumsden , T. J. T. Moore , J. C. Mottram , J. S. Urquhart , A. Cicchini