scholarly journals On the Methanol masers in G9.62+0.20E: Preliminary colliding-wind binary (CWB) calculations

2012 ◽  
Vol 8 (S287) ◽  
pp. 112-113
Author(s):  
S. P. van den Heever ◽  
D. J. van der Walt ◽  
J. M. Pittard ◽  
M. G. Hoare
Keyword(s):  
Light Curves ◽  
Continuum Emission ◽  
Hii Region ◽  
Star Forming ◽  
Methanol Maser ◽  
Methanol Masers ◽  
Maser Sources ◽  
The Continuum

AbstractA comparison between the observed periodic flaring of methanol maser sources in the star forming region G9.62+0.20E and the continuum emission from parts of a background HII region is made. Using a colliding wind binary (CWB) model preliminary calculations show that the CWB model results fit the maser light curves very well.

scholarly journals Millimetre wavelength methanol masers survey towards massive star forming regions

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.

scholarly journals Methanol masers: Evolutionary and kinematic tracers of massive star formation

2002 ◽  
Vol 206 ◽  
pp. 147-150
Author(s):  
Vincent Minier ◽  
Roy Booth ◽  
John Conway ◽  
Michele Pestalozzi
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Vlbi Observations ◽  
Methanol Masers ◽  
Maser Sources

We summarise our recent VLBI observations of a large sample of methanol maser sources associated with high-mass star-forming regions.

scholarly journals Distribution of the H2O Masers in the Sagittarius B2 Core

1989 ◽  
Vol 136 ◽  
pp. 181-187
Author(s):  
H. Kobayashi ◽  
M. Ishiguro ◽  
Y. Chikada ◽  
N. Ukita ◽  
K-I Morita ◽  
...  
Keyword(s):  
The Other ◽  
Velocity Spread ◽  
Wide Field ◽  
Positional Accuracy ◽  
Hii Region ◽  
Star Forming ◽  
The Face ◽  
Maser Sources ◽  
Total Velocity ◽  
The Continuum

The distribution of H2O masers in the Sgr B2 core was observed with a 2.5′×2.5′ wide field and with 540 km s−1 total velocity coverage by the Nobeyama Millimeter Array. Thirty-nine resolved maser spots were detected with a relative positional accuracy of 0.3″, which are clustered into four separate regions. In Sgr B2 north, the cluster lies at the edge of the continuum ridge. One of the maser spots shows strong and wide velocity-spread emission, suggesting it may correspond to a center of star forming activity. In Sgr B2 main, the strong maser spots are projected just on the face of a compact HII region, and are red-shifted relative to the central velocity of the HII region. There are two possibilities to interpret our results in Sgr B2 (M). One is that the H2O maser spots are distributed around the HII region and are infailing to the HII region. The other is that the H2O maser sources are associated with the cloud in the foreground of the HII region.

scholarly journals Masers in G34.3+0.2: What more can 6.7-GHz methanol masers tell us?

2002 ◽  
Vol 206 ◽  
pp. 159-162 ◽  
Author(s):  
Jiyune Yi ◽  
Chris J. Phillips ◽  
Roy S. Booth
Keyword(s):  
Massive Star ◽  
Continuum Emission ◽  
Evolutionary Stage ◽  
Hii Region ◽  
Methanol Maser ◽  
Methanol Masers ◽  
Water Masers

We present results of 6.7 GHz methanol maser observations using the European VLBI Network (EVN) toward the G34.3+0.2 complex, which contains a prototypical cometary HII region and a dust enshrouded, probably emerging massive star, G34.24+0.13. We have investigated the methanol maser distribution in both objects and compared it with the OH and water masers in the main HII region. The masers in G34.24+0.13 lie on top of the 1.3 mm continuum emission showing that methanol masers are present, even at this early evolutionary stage.

Exploring the Nature of MMB sources: A Search for Class I Methanol Masers and their Outflows

2017 ◽  
Vol 13 (S336) ◽  
pp. 317-318
Author(s):  
Nichol Cunningham ◽  
Gary Fuller ◽  
Adam Avison ◽  
Shari Breen
Keyword(s):  
Massive Star ◽  
Class Ii ◽  
Class I ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Initial Results ◽  
Maser Sources

AbstractWe present the initial results from a class I 44-GHz methanol maser follow-up survey, observed with the MOPRA telescope, towards 272 sources from the Methanol Multi-beam survey (MMB). Over half (∼60%) of the 6.7 GHz class II MMB maser sources are associated with a class I 44-GHz methanol maser at a greater than 5σ detection level. We find that class II MMB masers sources with an associated class I methanol maser have stronger peak fluxes compared to regions without an associated class I maser. Furthermore, as part of the MOPRA follow-up observations we simultaneously observed SiO emission which is a known tracer of shocks and outflows in massive star forming regions. The presence of SiO emission, and potentially outflows, is found to be strongly associated with the detection of class I maser emission in these regions.

scholarly journals The molecular environment of massive star forming cores associated with Class II methanol maser emission

2007 ◽  
Vol 3 (S242) ◽  
pp. 125-129
Author(s):  
S. N. Longmore ◽  
M. G. Burton ◽  
P. J. Barnes ◽  
T. Wong ◽  
C. R. Purcell ◽  
...  
Keyword(s):  
Massive Star ◽  
Class Ii ◽  
Dynamic State ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Maser Emission ◽  
Star Forming ◽  
Methanol Maser ◽  
Methanol Masers

AbstractMethanol maser emission has proven to be an excellent signpost of regions undergoing massive star formation (MSF). To investigate their role as an evolutionary tracer, we have recently completed a large observing program with the ATCA to derive the dynamical and physical properties of molecular/ionised gas towards a sample of MSF regions traced by 6.7GHz methanol maser emission. We find that the molecular gas in many of these regions breaks up into multiple sub-clumps which we separate into groups based on their association with/without methanol maser and cm continuum emission. The temperature and dynamic state of the molecular gas is markedly different between the groups. Based on these differences, we attempt to assess the evolutionary state of the cores in the groups and thus investigate the role of class II methanol masers as a tracer of MSF.

Long term 6.7 GHz methanol maser monitoring program

2017 ◽  
Vol 13 (S336) ◽  
pp. 277-278
Author(s):  
Artis Aberfelds ◽  
Ivar Shmeld ◽  
Karlis Berzins
Keyword(s):  
Radio Astronomy ◽  
Monitoring Program ◽  
Radio Telescopes ◽  
Methanol Maser ◽  
Data Registration ◽  
Methanol Masers ◽  
Maser Sources

AbstractThe first long-term maser (mainly methanol) monitoring program is under way with the radio telescopes of Ventspils International Radio Astronomy Center. The first activity of this program was to develop an observations methodology and data registration and reduction software for the Ventspils telescopes. The developed routines are to be used for maser variability monitoring, investigating short bursts of intensity and a search for new, previously unknown, maser sources. Currently the program consists of 41 methanol masers observed at 6.7 GHz, while new ones are periodically added. The maser sources are observed at 3 – 5 day intervals. It was found that most the sources display a significant level of variability with time, ranging from a few days, up to several months and, perhaps, years. In addition to non-varying masers, several types of maser variability behavior were observed, including: monotonic increases or decreases, un-periodical, quasi-periodic and periodic variations.

Sub-mm observations of periodic methanol masers

2017 ◽  
Vol 13 (S336) ◽  
pp. 301-302
Author(s):  
D. J. van der Walt ◽  
J.-M. Morgan ◽  
J. O. Chibueze ◽  
Q. Zhang
Keyword(s):  
Methanol Maser ◽  
Methanol Masers ◽  
Maser Sources

AbstractWe present the results of sub-millimetre observations on three periodic methanol maser sources. Our results indicate that there are geometric differences between some periodic methanol masers which have different variability profiles.

Zeeman Effect Observations in Class I Methanol Masers

2018 ◽  
Vol 14 (A30) ◽  
pp. 140-140
Author(s):  
Emmanuel Momjian ◽  
Anuj P. Sarma
Keyword(s):  
Zeeman Effect ◽  
Linear Structure ◽  
Class I ◽  
Star Forming ◽  
Methanol Maser ◽  
Star Forming Regions ◽  
Splitting Factor ◽  
Maser Line ◽  
Methanol Masers ◽  
Expected Values

AbstractWe report the detection of the Zeeman effect in the 44 GHz Class I methanol maser line toward the star forming region DR21W. The 44 GHz methanol masers in this source occur in a ∼3” linear structure that runs from northwest to southeast, with the two dominant components at each end, and several weaker maser components in between. Toward a 93 Jy maser in the dominant northwestern component, we find a significant Zeeman detection of −23.4 ± 3.2 Hz. If we use the recently published result of Lankhaar et al. (2018) that the F=5-4 hyperfine transition is responsible for the 44 GHz methanol maser line, then their value of z = −0.92 Hz mG−1 yields a line-of-sight magnetic field of Blos =25.4 ± 3.5 mG. If Class I methanol masers are pumped in high density regions with n∼107–8 cm−3, then magnetic fields in these maser regions should be a few to several tens of mG. Therefore, our result in DR21W is certainly consistent with the expected values.Using the above noted splitting factor in past Zeeman effect detections in Class I methanol masers reported by Sarma & Momjian (2011) and Momjian & Sarma (2017) in the star forming regions OMC-2 and DR21(OH) result in Blos values of 20.0 ± 1.2 mG and 58.2 ± 2.9 mG, respectively. These are also consistent with the expected values.

scholarly journals Imaging of selected sources from the Methanol Multibeam Survey

2007 ◽  
Vol 3 (S242) ◽  
pp. 184-185
Author(s):  
D. Wong-McSweeney ◽  
G. A. Fuller ◽  
S. Etoka
Keyword(s):  
Angular Resolution ◽  
Galactic Plane ◽  
High Angular Resolution ◽  
Maser Emission ◽  
Methanol Maser ◽  
Preliminary Results ◽  
Methanol Masers ◽  
Maser Sources

AbstractHigh angular resolution observations are essential for understanding the nature of maser emission and the sources which excite it. Here we present preliminary results from MERLIN observations of three methanol masers from the Toruń survey. These MERLIN observations are being analysed as part of the interferometric component of the Methanol Multibeam (MMB) Survey which is surveying the Galactic plane at |b|≤2° for 6.67 GHz methanol maser sources.

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