scholarly journals The Arecibo Methanol Maser Galactic Plane Survey

2007 ◽  
Vol 3 (S242) ◽  
pp. 208-212
Author(s):  
Jagadheep D. Pandian ◽  
Paul. F. Goldsmith ◽  
Avinash A. Deshpande
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Galactic Plane ◽  
Density Level ◽  
Massive Star Formation ◽  
Methanol Maser ◽  
Methanol Masers ◽  
Galactic Longitude ◽  
Early Phases ◽  
Spiral Arm

AbstractThe Arecibo Methanol Maser Galactic Plane Survey (AMGPS) is a blind survey for 6.7 GHz methanol masers in a section of the Galactic plane visible from the Arecibo radio telescope. The survey for these signposts of massive star formation is complete at a flux density level of 0.27 Jy making it the most sensitive blind survey for methanol masers carried out to date, and resulted in the detection of 86 methanol masers, 48 of which are new discoveries. The properties of methanol masers discovered in the survey are consistent with their being associated with early phases of massive star formation. The data also show the tangent point of the Carina-Sagittarius spiral arm to be around a Galactic longitude of 49.6°.

scholarly journals Methanol masers and massive star formation

2006 ◽  
Vol 2 (S237) ◽  
pp. 395-395
Author(s):  
Anna Bartkiewicz ◽  
Marian Szymczak ◽  
Huib Jan van Langevelde
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Galactic Plane ◽  
Spatial Scales ◽  
High Mass ◽  
Massive Star Formation ◽  
Infrared Surveys ◽  
Evolution Stage ◽  
Methanol Masers ◽  
Motion Studies

AbstractIt has been established that massive stars form in dense clusters, when large molecular clouds collapse. However, the high obscuration and small spatial scales make it difficult to investigate the earliest stage of high–mass protostellar objects (HMPOs). Therefore methanol masers are of special interests as they are closely associated with HMPOs and offer high spatial resolution; they probe the massive star formation environment at the unique scale of a few AU (1 mas corresponds to 5 AU at 5 kpc).We present VLBI observations of methanol masers discovered in an unbiased survey along the Galactic plane. We compare their positions with infrared surveys. In general, the masers do not coincide with infrared objects. That implies they are already present at a very early evolution stage of HMPOs when the dense surroundings still absorb other radiation. In addition we present maps of five methanol masers towards HMPOs with milliarcsecond resolution taken with the recently extended European VLBI Network. These sources show a wide variety of morphologies, indicating they arise in different events going on in close surroundings of HMPOs, i.e. outflows, discs or shocks. One source G23.657−00.127 displays a regularly shaped ring which appears as a great laboratory for further research of a single HMPO. Proper motion studies should reveal an expansion or rotation of the maser components in 2–3 years.

scholarly journals Probing the early phases of high-mass star formation with 6.7 GHz methanol masers

2019 ◽  
Vol 492 (1) ◽  
pp. 1335-1347
Author(s):  
Sonu Tabitha Paulson ◽  
Jagadheep D Pandian
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
High Mass ◽  
Spectral Energy ◽  
Mass Star ◽  
Spectral Energy Distributions ◽  
Massive Star Formation ◽  
Energy Distributions ◽  
Methanol Masers ◽  
Early Phases

ABSTRACT Methanol masers at 6.7 GHz are the brightest of class II methanol masers and have been found exclusively towards massive star-forming regions. These masers can thus be used as a unique tool to probe the early phases of massive star formation. We present here a study of the spectral energy distributions of 320 6.7 GHz methanol masers chosen from the Methanol Multibeam catalogue, which fall in the Hi-GAL range (|l| ≤ 60°, |b| ≤ 1°). The spectral energy distributions are constructed from 870 to 70 µm using data from the ATLASGAL and Hi-GAL surveys. The emission from cold dust is modelled by a single grey body component fit. We estimate the clump properties such as mass, far-infrared luminosity, and column density using the best-fitting parameters of the SED fits. Considering the Kauffman criteria for massive star formation, we find that all but a few maser hosts have the potential to harbour at least one high-mass star. The physical properties of the methanol maser hosts are also discussed. The evolutionary stages of 6.7 GHz maser sources, explored using the mass luminosity diagram, suggest that they are predominantly associated with high-mass stars with the majority being in the accretion phase. However, we observe a small number of sources that could possibly be related to intermediate- or low-mass stars.

scholarly journals VLBA Imaging of 12.2 GHz Methanol Masers

1998 ◽  
Vol 164 ◽  
pp. 375-376
Author(s):  
S. P. Ellingsen ◽  
P.M. McCulloch ◽  
P. J. Diamond ◽  
R. P. Norris
Keyword(s):  
Star Formation ◽  
Velocity Distribution ◽  
Massive Star ◽  
Star Formation Region ◽  
Formation Region ◽  
Maser Emission ◽  
Methanol Maser ◽  
Upper Limit ◽  
Methanol Masers ◽  
Right Ascension

AbstractWe have used the VLBA to image the 12.2 GHz (20-3−1 E) masing transition of methanol toward the massive star formation region G345.01+1.79. The maser spots are distributed in a curved structure with a near monotonic velocity distribution along the curve. The cluster of maser emission covers an area of approximately 200 milli-arcseconds in right ascension and 70 milli-arcseconds in declination.Comparison of the positions of the 12.2 GHz methanol maser spots in G345.01+1.79 as determined from the 1995 VLBA observations with 1988 Parkes-Tidbinbilla Interferometer observations shows that the relative positions of the maser spots detected in both epochs has changed by less than 5 milli-arcseconds during that interval. Assuming a distance of 2.3 kpc to G345.01+1.79 implies an upper limit on the relative tangential velocities of the maser spots of 7 km s−1.

scholarly journals The Spectral Energy Distribution of the Earliest Phases of Massive Star Formation

2015 ◽  
Vol 12 (S316) ◽  
pp. 151-152
Author(s):  
Randolf Klein ◽  
Jennifer Cooper ◽  
Leslie Looney ◽  
Thomas Henning ◽  
Sukanya Chakrabarti ◽  
...  
Keyword(s):  
Star Formation ◽  
Energy Distribution ◽  
Massive Star ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Status Report ◽  
Massive Star Formation ◽  
Data Set ◽  
Good Spatial Resolution ◽  
Early Phases

AbstractWe have selected cold and massive (M > 100M⊙) cores as candidates for early phases of star formation from millimeter continuum surveys without associations at short wavelengths. We compared the millimeter continuum peak positions with IR and radio catalogs and excluded cores that had sources associated with the cores’ peaks. We compiled a list of 173 cores in over 117 regions that are candidates for very early phases of Massive Star Formation (MSF). Now with the Spitzer and Herschel archives, these cores can be characterized further. We are compiling this data set to construct the complete spectral energy distribution (SED) in the mid- and far-infrared with good spatial resolution and broad spectral coverage. This allow us to disentangle the complex regions and model the SED of the deeply embedded protostars/clusters. We present a status report of our efforts: a preview of the IR properties of all cores and their embedded source inferred from a grey body fit to the compiled SEDs.

scholarly journals Chemical evolution in the early phases of massive star formation

2015 ◽  
Vol 579 ◽  
pp. A80 ◽  
Author(s):  
T. Gerner ◽  
Y. L. Shirley ◽  
H. Beuther ◽  
D. Semenov ◽  
H. Linz ◽  
...  
Keyword(s):  
Star Formation ◽  
Chemical Evolution ◽  
Massive Star ◽  
Massive Star Formation ◽  
Early Phases

scholarly journals A MERLIN study of 6 GHz excited OH & 6.7 GHz methanol masers in ON1

2007 ◽  
Vol 3 (S242) ◽  
pp. 188-189
Author(s):  
James A. Green ◽  
A. M. S. Richards ◽  
H. Flood ◽  
W. H. T. Vlemmings ◽  
R. J. Cohen
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Cross Correlation ◽  
Massive Star ◽  
Zeeman Splitting ◽  
Massive Star Formation ◽  
Star Formation Region ◽  
Formation Region ◽  
Methanol Masers ◽  
Field Strengths

AbstractMERLIN observations of 6.668-GHz Methanol and 6.035-GHz OH emission from the known massive star-formation region ON1 are presented. Maser components are found to lie at the southern edge of the UCHII with consistent polarization angles across the strongest features. Zeeman splitting of OH shows magnetic field strengths between +0.4 to −5.3 mG and from cross-correlation a tentative methanol magnetic field of −18mG is detected.

scholarly journals Ks-band, 2.14-µm Imaging of Southern Massive Star Formation Regions Traced by Methanol Masers

2009 ◽  
Vol 26 (4) ◽  
pp. 439-447 ◽  
Author(s):  
S. N. Longmore ◽  
M. G. Burton
Keyword(s):  
Star Formation ◽  
Point Source ◽  
Massive Star ◽  
Wide Field ◽  
Stellar Content ◽  
Massive Star Formation ◽  
Function Fitting ◽  
Spread Function ◽  
Methanol Masers ◽  
Star Formation Regions

AbstractWe present deep, wide-field, Ks-band (2.14-μm) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14-μm point source catalogues (PSCs) towards each of the regions. For the regions between 10° < l < 350° and |b| < 1, we match the 2.14-μm sources with the GLIMPSE point source catalogue to generate a combined 2.14- to 8.0-μm point source catalogue. We provide this data for the astronomical community to utilise in studies of the stellar content of embedded clusters.

Linear polarisation of Class I methanol masers in massive star formation regions

2017 ◽  
Vol 13 (S336) ◽  
pp. 243-246
Author(s):  
Ji-hyun Kang ◽  
Do-Young Byun ◽  
Kee-Tae Kim ◽  
Aran Lyo ◽  
Jongsoo Kim ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Star Forming ◽  
Methanol Maser ◽  
Follow Up Study ◽  
Star Forming Regions ◽  
Methanol Masers ◽  
Star Formation Regions ◽  
Linear Polarisation

AbstractWe present the results of the linear polarisation observations of methanol masers at 44 and 95 GHz towards 39 massive star forming regions (Kanget al.2016). These two lines are observed simultaneously with the 21-m Korean VLBI Network (KVN) telescope in single dish mode. About 60% of the observed showed fractional polarisation of a few percents at least at one of the two transition lines. We note that the linear polarisation of the 44 GHz methanol maser is first detected in this study including single dish and interferometer observations. We find the polarisation properties of these two lines are similar as expected, since they trace similar regions. As a follow-up study, we have carried out the VLBI polarisation observations toward some 44 GHz maser targets using the KVN telescope. We present preliminary VLBI polarisation results of G10.34-0.14, which show consistent polarisation properties in multiple epoch observations.

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 Methanol masers in the Herschel era Putting them in the star formation context

2012 ◽  
Vol 8 (S287) ◽  
pp. 492-496
Author(s):  
Michele Pestalozzi
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Galactic Plane ◽  
High Mass ◽  
Space Observatory ◽  
Methanol Maser ◽  
Open Time ◽  
The Galaxy ◽  
Methanol Masers ◽  
Using Data

AbstractMethanol masers are known to be among the most reliable tracers of high-mass stars in early stages of evolution. A number of searches across the Galaxy has yielded to date, a complete census of those masers in two thirds of the Milky Way, providing a catalogue of some 800 sources to be studied in depth. In particular, it is important to characterise the physical properties of the objects hosting methanol masers, and this is possible today using data from the Herschel Space Observatory (HSO). The exceptional spatial resolution of HSO and its wavelength coverage are perfectly tuned to put the methanol maser phase into its star formation context. This paper presents results on the characterisation of methanol maser hosts using Herschel data from the Hi-GAL project, an Open Time Key Project to survey the inner Galactic plane at 5 wavelengths between 70 and 500 μm.

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