Physical Conditions and Heating/Cooling Processes in High Mass Star Formation Regions

1991 ◽  
pp. 155-220 ◽  
Author(s):  
Reinhard Genzel
Keyword(s):  
Star Formation ◽  
High Mass ◽  
Mass Star ◽  
Physical Conditions ◽  
Star Formation Regions

A golden age for maser surveys

2017 ◽  
Vol 13 (S336) ◽  
pp. 219-224
Author(s):  
Shari L. Breen
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
High Mass ◽  
Mass Star ◽  
Physical Conditions ◽  
Multi Wavelength ◽  
The Subject ◽  
To Come ◽  
Star Formation Regions ◽  
Made In

AbstractMasers are becoming increasingly important probes of high-mass star formation, revealing details about the kinematics and physical conditions at the elusive, early stages of formation. Over the last decade significant investment has been made in a number of large-scale, sensitive maser surveys targeting transitions found in the vicinity of young, high-mass stars. Individually, these searches have led to valuable insights into maser populations, their associated star formation regions, and often revealed further details such as Galactic structure. In combination, they become even more powerful, especially when considered together with complementary multi-wavelength data. Another consequence of large maser surveys has been the identification of a number of especially interesting sources that have been the subject of subsequent detailed studies. I summarize the recent plethora of maser surveys, their results, and how they are contributing to our understanding of star formation. Ongoing searches will ensure a bright future of maser surveys in the decade to come.

scholarly journals High Resolution Radio Continuum Observations of High Mass Star Formation Regions

2001 ◽  
Vol 205 ◽  
pp. 280-281
Author(s):  
S. Kurtz ◽  
P. Hofner ◽  
C. Vargas ◽  
W. Díaz-Merced
Keyword(s):  
Star Formation ◽  
Radio Continuum ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
High Quality ◽  
Very Large Array ◽  
Adverse Conditions ◽  
Star Formation Regions ◽  
Calibration Techniques

We present high angular resolution centimeter and millimeter continuum observations of several galactic massive star formation regions. Using calibration techniques pioneered at the Very Large Array, we are able to obtain high quality images even under adverse conditions of phase stability. Techniques such as these will be essential if future millimeter arrays are to obtain high quality and high precision images. We provide a current summary of our on-going survey, and present images and a brief discussion of several of the more intriguing sources.

scholarly journals Masers as evolutionary tracers of high-mass star formation

2012 ◽  
Vol 8 (S287) ◽  
pp. 156-160 ◽  
Author(s):  
Shari L. Breen ◽  
Simon P. Ellingsen
Keyword(s):  
Star Formation ◽  
Point Sources ◽  
Radio Continuum ◽  
High Mass ◽  
Mass Star ◽  
Evolutionary Scheme ◽  
Evolutionary Clock ◽  
The Common ◽  
Star Formation Regions ◽  
Made In

AbstractDetermining an evolutionary clock for high-mass star formation is an important step towards realising a unified theory of star formation, as it will enable qualitative studies of the associated high-mass stars to be executed. We have carried out detailed studies of a large number of sources suspected of undergoing high-mass star formation and have found that common maser transitions offer the best opportunity to determine an evolutionary scheme for these objects. We have investigated the relative evolutionary phases of massive star formation associated with the presence or absence of combinations of water, methanol and main-line hydroxyl masers. The locations of the different maser species have been compared with the positions of 1.2 mm dust clumps, radio continuum, GLIMPSE point sources and Extended Green Objects. Comparison between the characteristics of coincident sources has revealed strong evidence for an evolutionary sequence for the different maser species in high-mass star formation regions. We present our proposed sequence for the presence of the common maser species associated with young high-mass stars and highlight recent advances. We discuss future investigations that will be made in this area by comparing data from the Methanol Multibeam (MMB) Survey with chemical clocks from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) Survey.

scholarly journals Ammonia towards dust clumps in the giant molecular cloud associated with RCW 106

2012 ◽  
Vol 8 (S292) ◽  
pp. 50-50
Author(s):  
Vicki Lowe ◽  
Maria R. Cunningham ◽  
James S. Urquhart ◽  
Shinji Horiuchi
Keyword(s):  
Star Formation ◽  
Radio Telescope ◽  
Molecular Cloud ◽  
Galactic Plane ◽  
High Mass ◽  
Mass Star ◽  
Giant Molecular Clouds ◽  
Molecular Line ◽  
Star Forming ◽  
Star Formation Regions

AbstractHigh-mass stars are known to be born within giant molecular clouds (GMCs); However, the exact processes involved in forming a high-mass star are still not well understood. It is clear that high-mass stars do not form in isolation, and that the processes surrounding high-mass star formation may affect the environment of the entire molecular cloud. We are studying the GMC associated with RCW 106 (G333), which is one of the most active massive-star formation regions in the Galactic plane. This GMC, located at l = 333° b = − 0.5°, has been mapped in over 20 molecular line transitions with the Mopra radio telescope (83-110 GHz), in Australia, and with the Swedish-ESO Submillimeter Telescope (SEST) in the 1.2 mm cool dust continuum. The region is also within the Spitzer GLIMPSE infrared survey (3.6, 4.5, 5.8, and 8.0 μm) area. We have decomposed the dust continuum using a clump-finding algorithm (CLUMPFIND), and are using the multiple molecular line traditions from the Mopra radio telescope to classify the type and stage of star formation taking place therein. Having accurate physical temperatures of the star forming clumps is essential to constrain other parameters to within useful limits. To achieve this, we have obtained pointed NH3 observations from the Tidbinbilla 70-m radio telescope, in Australia, towards these clumps.

scholarly journals A Sensitive Search for Predicted Methanol Maser Transitions with the Australia Telescope Compact Array

2016 ◽  
Vol 33 ◽  
Author(s):  
A. Chipman ◽  
S. P. Ellingsen ◽  
A. M. Sobolev ◽  
D. M. Cragg
Keyword(s):  
Star Formation ◽  
Class Ii ◽  
High Mass ◽  
Mass Star ◽  
Radio Telescopes ◽  
Methanol Maser ◽  
Upper Limit ◽  
Methanol Masers ◽  
Star Formation Regions ◽  
Compact Array

AbstractWe have used the Australia Telescope Compact Array to search for a number of centimetre wavelength methanol transitions which are predicted to show weak maser emission towards star formation regions. Sensitive, high spatial, and spectral resolution observations towards four high-mass star formation regions which show emission in a large number of class II methanol maser transitions did not result in any detections. From these observations, we are able to place an upper limit of ≲ 1300 K on the brightness temperature of any emission from the 31A+–31A−, 17−2–18−3 E (vt = 1), 124–133 A−, 124–133 A+, and 41A+–41A− transitions of methanol in these sources on angular scales of 2 arcsec. This upper limit is consistent with current models for class II methanol masers in high-mass star formation regions and better constraints than those provided here will likely require observations with next-generation radio telescopes.

scholarly journals Confirmation of the exclusive association between 6.7-GHz methanol masers and high-mass star formation regions

2013 ◽  
Vol 435 (1) ◽  
pp. 524-530 ◽  
Author(s):  
S. L. Breen ◽  
S. P. Ellingsen ◽  
Y. Contreras ◽  
J. A. Green ◽  
J. L. Caswell ◽  
...  
Keyword(s):  
Star Formation ◽  
High Mass ◽  
Mass Star ◽  
Methanol Masers ◽  
Star Formation Regions

scholarly journals VERY LARGE ARRAY OBSERVATIONS OF AMMONIA IN HIGH-MASS STAR FORMATION REGIONS

2014 ◽  
Vol 790 (2) ◽  
pp. 84 ◽  
Author(s):  
Xing Lu ◽  
Qizhou Zhang ◽  
Hauyu Baobab Liu ◽  
Junzhi Wang ◽  
Qiusheng Gu
Keyword(s):  
Star Formation ◽  
High Mass ◽  
Mass Star ◽  
Large Array ◽  
Very Large Array ◽  
Star Formation Regions

scholarly journals Class I methanol masers in low-mass star formation regions

2012 ◽  
Vol 8 (S287) ◽  
pp. 161-165
Author(s):  
S. V. Kalenskii ◽  
V. I. Slysh ◽  
L. E. B. Johansson ◽  
P. Bergman ◽  
S. Kurtz ◽  
...  
Keyword(s):  
Star Formation ◽  
Class I ◽  
High Mass ◽  
Mass Star ◽  
Brightness Temperatures ◽  
Low Mass ◽  
Methanol Masers ◽  
Star Formation Regions ◽  
Diagram Analysis ◽  
Maser Sources

AbstractFour Class I maser sources were detected at 44, 84, and 95 GHz toward chemically rich outflows in the regions of low-mass star formation NGC 1333I4A, NGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a similar outflow, NGC 2023. Flux densities of the newly detected masers are no more than 18 Jy, being much lower than those of strong masers in regions of high-mass star formation. The brightness temperatures of the strongest peaks in NGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of the peak in NGC 1333I2A is only 176 K. However, a rotational diagram analysis showed that the latter source is also a maser. The main properties of the newly detected masers are similar to those of Class I methanol masers in regions of massive star formation. The former masers are likely to be an extension of the latter maser population toward low luminosities of both the masers and the corresponding YSOs.

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