SIMULTANEOUS OBSERVATION OF WATER AND CLASS I METHANOL MASERS TOWARD CLASS II METHANOL 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.

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44 GHz Methanol Maser Surveys

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312006795 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 133-140

Author(s):

S. E. Kurtz

Keyword(s):

Star Formation ◽

Formation Process ◽

Class Ii ◽

Class I ◽

High Mass ◽

Mass Star ◽

Star Forming ◽

Methanol Maser ◽

Star Forming Regions ◽

Methanol Masers

AbstractClass I 44 GHz methanol masers are not as well-known, as common, or as bright as their more famous Class II cousins at 6.7 and 12.2 GHz. Nevertheless, the 44 GHz masers are commonly found in high-mass star forming regions. At times they appear to trace dynamically important phenomena; at other times they show no obvious link to the star formation process. Here, we summarize the major observational efforts to date, including both dedicated surveys and collateral observations. The principal results are presented, some that were expected, and others that were unexpected.

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44-GHz class I methanol maser survey towards 6.7-GHz class II methanol masers

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312007156 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 284-285 ◽

Cited By ~ 2

Author(s):

Do-Young Byun ◽

Kee-Tae Kim ◽

Jae-Han Bae

Keyword(s):

Class Ii ◽

Class I ◽

Young Stellar Objects ◽

High Mass ◽

Radio Telescopes ◽

Stellar Objects ◽

Methanol Maser ◽

Peak Flux ◽

Methanol Masers ◽

Water Maser

AbstractThe Class II 6.7-GHz methanol maser is a tracer of high mass young stellar objects. We present results of a 44-GHz class I methanol maser and 22-GHz water maser survey using the KVN (Korean VLBI Network) 21-m single dish radio telescopes towards 284 6.7-GHz maser sites. Class I methanol maser and water maser emission is detected towards 116 (41%) and 136 (48%) sources, respectively. About 50 sources have a peak flux density higher than 10 Jy at 44-GHz. They are candidates for VLBI studies using the KVN.

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Class I Methanol Maser Emission in NGC 4945

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317010687 ◽

2017 ◽

Vol 13 (S336) ◽

pp. 105-108

Author(s):

Tiege P. McCarthy ◽

Simon P. Ellingsen ◽

Xi Chen ◽

Shari L. Breen ◽

Maxim A. Voronkov ◽

...

Keyword(s):

Large Scale ◽

Class I ◽

Molecular Gas ◽

Low Velocity ◽

Extragalactic Source ◽

Maser Emission ◽

Methanol Maser ◽

Methanol Masers

AbstractWe have detected maser emission from the 36.2 GHz (4−1 → 30E) methanol transition towards NGC 4945. This emission has been observed in two separate epochs and is approximately five orders of magnitude more luminous than typical emission from this transition within our Galaxy. NGC 4945 is only the fourth extragalactic source observed hosting class I methanol maser emission. Extragalactic class I methanol masers do not appear to be simply highly-luminous variants of their galactic counterparts and instead appear to trace large-scale regions where low-velocity shocks are present in molecular gas.

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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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The detection of new methanol masers in the 5−1 — 40E Line

Symposium - International Astronomical Union ◽

10.1017/s0074180900222390 ◽

2002 ◽

Vol 206 ◽

pp. 195-198

Author(s):

Sergei V. Kalenskii ◽

Vyacheslav I. Slysh ◽

Irina E. Val'tts ◽

Anders Winnberg ◽

Lars E. B. Johansson

Keyword(s):

Velocity Field ◽

Frequency Analysis ◽

Linear Polarization ◽

Class I ◽

Narrow Line ◽

Bipolar Outflow ◽

Compact Class ◽

Extended Sources ◽

Methanol Masers ◽

Maser Sources

Fifty-one objects in the 5−1 − 40E methanol line at 84.5 GHz was detected during a survey of Class I maser sources. Narrow maser features were found in 17 of these. Broad quasi-thermal lines were detected towards other sources. One of the objects with narrow features, the young bipolar outflow L 1157 was also observed in the 80 − 71A+ line at 95.2 GHz; a narrow line was detected at this frequency. Analysis showed that the broad lines are usually inverted. The quasi-thermal profiles imply that the line opacities are not larger than several units. These results confirm the plausibility of models in which compact Class I masers appear in extended sources as a result of an appropriate velocity field.Measurements of linear polarization at 84.5 GHz in 13 sources were made. No polarization was found except a tentative detection of a weak polarization in M 8E.

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The evolutionary status of protostellar clumps hosting class II methanol masers

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa233 ◽

2020 ◽

Vol 493 (2) ◽

pp. 2015-2041 ◽

Cited By ~ 1

Author(s):

B M Jones ◽

G A Fuller ◽

S L Breen ◽

A Avison ◽

J A Green ◽

...

Keyword(s):

Galactic Plane ◽

Dust Emission ◽

Principal Component ◽

Far Infrared ◽

Class Ii ◽

Young Stellar Objects ◽

Galactic Centre ◽

Evolutionary Status ◽

Methanol Maser ◽

Methanol Masers

ABSTRACT The Methanol MultiBeam survey (MMB) provides the most complete sample of Galactic massive young stellar objects (MYSOs) hosting 6.7 GHz class II methanol masers. We characterize the properties of these maser sources using dust emission detected by the Herschel Infrared Galactic Plane Survey (Hi-GAL) to assess their evolutionary state. Associating 731 (73 per cent) of MMB sources with compact emission at four Hi-GAL wavelengths, we derive clump properties and define the requirements of an MYSO to host a 6.7 GHz maser. The median far-infrared (FIR) mass and luminosity are 630 M⊙ and 2500 L⊙ for sources on the near side of Galactic centre and 3200 M⊙ and 10000 L⊙ for more distant sources. The median luminosity-to-mass ratio is similar for both at ∼4.2 L⊙ M⊙−1. We identify an apparent minimum 70 μm luminosity required to sustain a methanol maser of a given luminosity (with $L_{70} \propto L_{6.7}\, ^{0.6}$). The maser host clumps have higher mass and higher FIR luminosities than the general Galactic population of protostellar MYSOs. Using principal component analysis, we find 896 protostellar clumps satisfy the requirements to host a methanol maser but lack a detection in the MMB. Finding a 70 μm flux density deficiency in these objects, we favour the scenario in which these objects are evolved beyond the age where a luminous 6.7 GHz maser can be sustained. Finally, segregation by association with secondary maser species identifies evolutionary differences within the population of 6.7GHz sources.

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Long term 6.7 GHz methanol maser monitoring program

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317009437 ◽

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.

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Sub-mm observations of periodic methanol masers

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317010699 ◽

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.

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