Outflow and Infall in a Sample of Massive Star Forming Regions. II. Large‐Scale Kinematics

AbstractThe newly discovered Massive Molecular Filament (MMF) G32.02+0.05 (~ 70 pc long, 105 M⊙) has been shaped and compressed by older generations of massive stars. The similarity of this filament in physical structure (density profile, temperature) to much smaller star-forming filaments, suggests that the mechanism to form such filaments may be a universal process. The densest portion of the filament, apparent as an Infrared Dark Cloud (IRDC) shows a range of massive star formation signatures throughout. We investigate the kinematics in this filament and find widespread inverse P cygni asymmetric line profiles. These line asymmetries are interpreted as a signature of large-scale radial collapse. Using line asymmetries observed with optically thick HCO+ (1-0) and optically thin H13CO+ (1-0) across a range of massive star forming regions in the filament, we estimate the global radial infall rate of the filament to range from a few 100 to a few 1000 M⊙ Myr−1 pc−1. At its current infall rate the densest portions of the cloud will more than double their current mass within a Myr.

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The large-scale distribution and physical properties of massive star forming regions in the Milky Way

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307013026 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 228-229

Author(s):

Jarken Esimbek ◽

Zhou Jianjun ◽

Zheng Xingwu

Keyword(s):

Physical Properties ◽

Large Scale ◽

Massive Star ◽

Milky Way ◽

Spectral Lines ◽

Recombination Line ◽

Star Forming ◽

Star Forming Regions ◽

Hydrogen Recombination ◽

Large Survey

AbstractWe are conducting a large survey with the Urumqi 25 m radio telescope to study the distribution and physical properties of massive star forming regions in the Milky Way. We will accomplish this by observing the H110α hydrogen recombination line at 4.874 GHz and the H2CO absorption line at 4830 GHz. These lines are associated with compact HII regions and dense molecular clouds. As a test of the 6 cm spectral line receiving system, we observed the two spectral lines toward massive star forming regions. We plan to study the large scale distribution and physical properties of massive star forming regions in the Milky way.

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Maser Astrometry: from Galactic Structure to Local Group Cosmology

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312007314 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 359-367 ◽

Cited By ~ 2

Author(s):

Mark J. Reid

Keyword(s):

Large Scale ◽

Massive Star ◽

Milky Way ◽

Local Group ◽

Galactic Structure ◽

Proper Motions ◽

Star Forming ◽

Fundamental Parameters ◽

3 Dimensional ◽

Star Forming Regions

AbstractThis review summarizes current advances in astrometry of masers as they pertain to large-scale Galactic structure and dynamics and Local Group cosmology. Parallaxes and proper motions have now been measured for more than 60 massive star forming regions using the Japanese VERA array, the EVN and the VLBA. These results provide “gold standard” distances and 3-dimensional velocities for sources across the Milky Way, revealing its spiral structure. Modeling these data tightly constrains the fundamental parameters of the Milky Way: R0 and Θ0. Proper motions of Local Group galaxies have been measured, improving our understanding of the history and fate of the Group.

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LARGE-SCALE KINEMATICS, ASTROCHEMISTRY, AND MAGNETIC FIELD STUDIES OF MASSIVE STAR-FORMING REGIONS THROUGH HC3N, HNC, AND C2H MAPPINGS

The Astrophysical Journal ◽

10.1088/0004-637x/745/1/47 ◽

2011 ◽

Vol 745 (1) ◽

pp. 47 ◽

Cited By ~ 33

Author(s):

Juan Li ◽

Junzhi Wang ◽

Qiusheng Gu ◽

Zhi-yu Zhang ◽

Xingwu Zheng

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Massive Star ◽

Field Studies ◽

Star Forming ◽

Star Forming Regions

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OH masers and magnetic fields in massive star-forming regions: ON1

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002402 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 452-452

Author(s):

S. Nammahachak ◽

K. Asanok ◽

B. Hutawarakorn Kramer ◽

R. J. Cohen ◽

O. Muanwong ◽

...

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Massive Star ◽

Zeeman Splitting ◽

Young Stars ◽

Star Forming ◽

Physical Conditions ◽

Bipolar Outflow ◽

Star Forming Regions ◽

The Magnetic Field

AbstractOH masers are sensitive probes of the kinematics and physical conditions, and give unique information on the magnetic field through their polarization. Zeeman splitting of the OH lines can give the magnetic field strength and direction. Observing OH masers with MERLIN we studied the bipolar outflow in the star-forming region ON1, which hosts one of the earliest known ultra-compact (UC) HII regions. The strongest masers lie near the southern edge of the UCHII region in an elongated distribution. The maser distribution is orthogonal to the bipolar outflow seen in HCO+, suggesting that the OH masers may be embedded in a molecular disk or torus around a young B0.3 star, most likely tracing a shock front. An isolated group of 1720-MHz masers is also seen to the East. The magnetic field deduced from Zeeman splitting of the OH maser lines shows a large-scale order, with field values ranging from -0.4 to -4.6 mG. These results add to the growing body of evidence for OH masers associated with molecular disks or tori at the centre of bipolar outflow from massive young stars, and for a significant role played by the magnetic field in generating or channeling the bipolar outflow. Further details are presented by Nammahachak et al. 2006.

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AKARI OBSERVATIONS OF MASSIVE STAR-FORMING REGIONS INDICATIVE OF LARGE-SCALE CLOUD-CLOUD COLLISIONS

Publications of The Korean Astronomical Society ◽

10.5303/pkas.2017.32.1.123 ◽

2017 ◽

Vol 32 (1) ◽

pp. 123-125

Author(s):

Yasuki Hattori ◽

Hidehiro Kaneda ◽

Daisuke Ishihara ◽

Mitsuyoshi Yamagishi ◽

Toru Kondo ◽

...

Keyword(s):

Large Scale ◽

Massive Star ◽

Star Forming ◽

Star Forming Regions

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Different Evolutionary Stages in the Massive Star-forming Complex W3 Main

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313000768 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 116-116

Author(s):

Yuan Wang ◽

Henrik Beuther ◽

Qizhou Zhang ◽

Arjan Bik ◽

Javier A. Rodón ◽

...

Keyword(s):

Star Formation ◽

Large Scale ◽

Massive Star ◽

Chemical Properties ◽

Hii Regions ◽

High Mass ◽

Mass Star ◽

Star Forming ◽

Star Forming Regions ◽

And Chemical Properties

AbstractWe observed with the Submillimeter Array and IRAM 30 m telescope three high-mass star-forming regions in different evolutionary stages in the W3 high-mass star formation complex. These regions, i.e. W3 SMS1 (W3 IRS5), SMS2 (W3 IRS4) and SMS3, are located within the same large-scale environment, which allows us to study rotation and outflows as well as chemical properties in an evolutionary sense. While we find multiple mm continuum sources toward all regions, these three subregions exhibit different dynamical and chemical properties, which indicates that they are in different evolutionary stages. Even within each sub-region, massive cores of different ages are found, e.g. in SMS2, sub-sources from the most evolved UCHii region to potential starless cores exist within 30 000 AU (left panel, Fig. 1). Outflows and rotational structures are found in SMS1 and SMS2. Evidence for interactions between the molecular cloud and the HII regions is found in the 13CO channel maps (right panel, Fig. 1), which may indicate triggered star formation.

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The Circumstellar Environment of Embedded Massive Stars

Highlights of Astronomy ◽

10.1017/s1539299600013083 ◽

2002 ◽

Vol 12 ◽

pp. 143-145 ◽

Cited By ~ 1

Author(s):

Lee G. Mundy ◽

Friedrich Wyrowski ◽

Sarah Watt

Keyword(s):

Massive Star ◽

Massive Stars ◽

Low Mass Stars ◽

Submillimeter Wavelength ◽

Star Forming ◽

Star Forming Regions ◽

Low Mass ◽

Circumstellar Environments ◽

Near Future

Millimeter and submillimeter wavelength images of massive star-forming regions are uncovering the natal material distribution and revealing the complexities of their circumstellar environments on size scales from parsecs to 100’s of AU. Progress in these areas has been slower than for low-mass stars because massive stars are more distant, and because they are gregarious siblings with different evolutionary stages that can co-exist even within a core. Nevertheless, observational goals for the near future include the characterization of an early evolutionary sequence for massive stars, determination if the accretion process and formation sequence for massive stars is similar to that of low-mass stars, and understanding of the role of triggering events in massive star formation.

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Millimetre wavelength methanol masers survey towards massive star forming regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307013051 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 234-235

Author(s):

T. Umemoto ◽

N. Mochizuki ◽

K. M. Shibata ◽

D.-G. Roh ◽

H.-S. Chung

Keyword(s):

Detection Rate ◽

Massive Star ◽

Molecular Line ◽

Maser Emission ◽

Star Forming ◽

Methanol Maser ◽

Physical Conditions ◽

Star Forming Regions ◽

Methanol Masers ◽

Maser Sources

AbstractWe present the results of a mm wavelength methanol maser survey towards massive star forming regions. We have carried out Class II methanol maser observations at 86.6 GHz, 86.9 GHz and 107.0 GHz, simultaneously, using the Nobeyama 45 m telescope. We selected 108 6.7 GHz methanol maser sources with declinations above −25 degrees and fluxes above 20 Jy. The detection limit of maser observations was ~3 Jy. Of the 93 sources surveyed so far, we detected methanol emission in 25 sources (27%) and “maser” emission in nine sources (10%), of which thre “maser” sources are new detections. The detection rate for maser emission is about half that of a survey of the southern sky (Caswell et al. 2000). There is a correlation between the maser flux of 107 GHz and 6.7 GHz/12 GHz emission, but no correlation with the “thermal” (non maser) emission. From results of other molecular line observations, we found that the sources with methanol emission show higher gas temperatures and twice the detection rate of SiO emission. This may suggest that dust evaporation and destruction by shock are responsible for the high abundance of methanol molecules, one of the required physical conditions for maser emission.

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