scholarly journals The Physical Parameters of Clumps Associated with Class I Methanol Masers

2020 ◽  
Vol 160 (5) ◽  
pp. 213
Author(s):  
Dmitry A. Ladeyschikov ◽  
James S. Urquhart ◽  
Andrey M. Sobolev ◽  
Shari L. Breen ◽  
Olga S. Bayandina
Keyword(s):  
Class I ◽  
Physical Parameters ◽  
Methanol Masers

Class I Methanol Maser Emission in NGC 4945

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.

scholarly journals Class I methanol masers in the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 147-149
Author(s):  
L. O. Sjouwerman ◽  
Y. M. Pihlström
Keyword(s):  
Galactic Center ◽  
Class I ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Sagittarius A ◽  
Current Location ◽  
Theoretical Predictions ◽  
Methanol Masers ◽  
Sgr A

AbstractWe report on the detection of 36 and 44 GHz Class I methanol (CH3OH) maser emission in the Sagittarius A (Sgr A) complex with the Karl G. Jansky Very Large Array (VLA). These VLA observations show that the Sgr A complex harbors at least three different maser tracers of shocked regions in the radio regime. The 44 GHz masers correlate with the positions and velocities of previously detected 36 GHz CH3OH masers, but less with 1720 MHz OH masers. Our detections agree with theoretical predictions that the densities and temperatures conducive for 1720 MHz OH masers may also produce 36 and 44 GHz CH3OH maser emission. However, many 44 GHz masers do not overlap with 36 GHz methanol masers, suggesting that 44 GHz masers also arise in regions too hot and too dense for 36 GHz masers to form. This agrees with the non-detection of 1720 MHz OH masers in the same area, which are thought to be excited under even cooler and less dense conditions. We speculate that the geometry of the 36 GHz masers outlines the current location of a shock front.

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

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.

scholarly journals Interferometry of class I methanol masers, statistics and the distance scale

2017 ◽  
Vol 13 (S336) ◽  
pp. 158-161
Author(s):  
Maxim A. Voronkov ◽  
Shari L. Breen ◽  
Simon P. Ellingsen ◽  
Christopher H. Jordan
Keyword(s):  
Angular Resolution ◽  
Class I ◽  
High Angular Resolution ◽  
Current Form ◽  
Young Stellar Object ◽  
Linear Distance ◽  
Kinematic Method ◽  
Future Potential ◽  
Methanol Masers ◽  
Compact Array

AbstractThe Australia Telescope Compact Array (ATCA) participated in a number of survey programs to search for and image common class I methanol masers (at 36 and 44 GHz) with high angular resolution. In this paper, we discuss spatial and velocity distributions revealed by these surveys. In particular, the number of maser regions is found to fall off exponentially with the linear distance from the associated young stellar object traced by the 6.7-GHz maser, and the scale of this distribution is 263±15 milliparsec. Although this relationship still needs to be understood in the context of the broader field, it can be utilised to estimate the distance using methanol masers only. This new technique has been analysed to understand its limitations and future potential. It turned out, it can be very successful to resolve the ambiguity in kinematic distances, but, in the current form, is much less accurate (than the kinematic method) if used on its own.

scholarly journals ALMA OBSERVATIONS OF THE IRDC CLUMP G34.43+00.24 MM3: 278 GHz CLASS I METHANOL MASERS

2014 ◽  
Vol 794 (1) ◽  
pp. L10 ◽  
Author(s):  
Takahiro Yanagida ◽  
Takeshi Sakai ◽  
Tomoya Hirota ◽  
Nami Sakai ◽  
Jonathan B. Foster ◽  
...  
Keyword(s):  
Class I ◽  
Methanol Masers

scholarly journals Class I and Class II methanol masers in high-mass star-forming regions

2010 ◽  
Vol 517 ◽  
pp. A56 ◽  
Author(s):  
F. Fontani ◽  
R. Cesaroni ◽  
R. S. Furuya
Keyword(s):  
Class Ii ◽  
Class I ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Methanol Masers

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.

Pumping regimes of Class I methanol masers

2017 ◽  
Vol 13 (S336) ◽  
pp. 57-58 ◽  
Author(s):  
A. M. Sobolev ◽  
S. Yu. Parfenov
Keyword(s):  
Observational Data ◽  
Current Paper ◽  
Class I ◽  
Methanol Maser ◽  
Theoretical Paper ◽  
Methanol Masers ◽  
Theoretical Considerations

AbstractIn the current paper we describe results of an extensive and refined analysis which shows that the beaming leads to considerable changes in the model line ratios and brightness estimates. For example, beaming shifts the locus of the brightest masers to the lower values of the gas densities. Recent theoretical paper by Leurini et al. (2016) presented extensive consideration of the Class I methanol maser (MMI) pumping. Their study allowed to distinguish only 3 of 4 MMI pumping regimes found in Sobolev et al. (2005) and Sobolev et al. (2007) on the basis of analysis of observational data combined with theoretical considerations. The regime when the line from the J−2 − (J − 1)−1E series is the brightest was missing in Leurini et al. (2016) results. This may be explained by considering the fact that the authors did not take into account considerable beaming effects.

scholarly journals Variability in extragalactic class I methanol masers: new maser components towards NGC 4945 and NGC 253

2019 ◽  
Vol 491 (4) ◽  
pp. 4642-4655
Author(s):  
T P McCarthy ◽  
S P Ellingsen ◽  
S L Breen ◽  
M A Voronkov ◽  
X Chen ◽  
...  
Keyword(s):  
Class I ◽  
Continuum Emission ◽  
Imaging Procedures ◽  
Upper Limit ◽  
Upper Limits ◽  
Maser Line ◽  
Density Values ◽  
Methanol Masers ◽  
Compact Array

ABSTRACT We have used the Australia Telescope Compact Array (ATCA) to make new observations of the 36.2-GHz (4−1 → 30E) methanol transition towards NGC 4945 and NGC 253. These observations have revealed the presence of new maser components towards these galaxies, and have provided the first clear evidence for variability in extragalactic class I methanol masers. Alongside the new observations of NGC 4945 and NGC 253, we present the results of recent 36.2-GHz methanol maser searches towards 12 galaxies, placing upper limits on the emission from the 36.2-GHz class I transition and the 37.7-GHz (72 → 81E) class II maser line towards these sources. Flux density values for the 7-mm continuum emission towards these sources are also reported where applicable. A re-analysis of the published 36.2-GHz methanol observations of Arp 220 undertaken as part of the search revealed some issues with previous imaging procedures. The re-analysis, combined with non-detections in independent follow-up observations, suggests that there is no 36.2-GHz methanol emission towards Arp 220 stronger than 3.5 mJy in a 10 km s−1 channel (5σ upper limit).

scholarly journals Online Database of Class I Methanol Masers

2019 ◽  
Vol 158 (6) ◽  
pp. 233 ◽  
Author(s):  
Dmitry A. Ladeyschikov ◽  
Olga S. Bayandina ◽  
Andrey M. Sobolev
Keyword(s):  
Class I ◽  
Online Database ◽  
Methanol Masers
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