scholarly journals Images of Astrophysical Masers and their Variability in a Turbulent Medium: The 25 GHz Methanol Masers

2003 ◽  
Vol 590 (1) ◽  
pp. 333-339 ◽  
Author(s):  
A. M. Sobolev ◽  
W. D. Watson ◽  
V. A. Okorokov
Keyword(s):  
Turbulent Medium ◽  
Methanol Masers

scholarly journals Astrophysical Maser Radiation from a Turbulent Medium: Application to 25 GHz Methanol Masers

1998 ◽  
Vol 498 (2) ◽  
pp. 763-772 ◽  
Author(s):  
A. M. Sobolev ◽  
B. K. Wallin ◽  
W. D. Watson
Keyword(s):  
Turbulent Medium ◽  
Maser Radiation ◽  
Methanol Masers

VLBA Observations of 12 GHz Methanol Masers toward W3(OH)

1999 ◽  
Vol 519 (1) ◽  
pp. 244-256 ◽  
Author(s):  
L. Moscadelli ◽  
K. M. Menten ◽  
C. M. Walmsley ◽  
M. J. Reid
Keyword(s):  
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.

14 years of 6.7 GHz periodic methanol maser observations towards G188.95+0.89

2019 ◽  
Vol 15 (S356) ◽  
pp. 393-394
Author(s):  
Martin M. Mutie ◽  
Paul Baki ◽  
James O. Chibueze ◽  
Khadija El Bouchefry
Keyword(s):  
Radio Telescope ◽  
Exponential Decay ◽  
Hii Regions ◽  
Monitoring Period ◽  
Methanol Maser ◽  
Spectral Components ◽  
Methanol Masers ◽  
Compact Hii Regions

AbstractWe report the results of 14 years of monitoring of G188.95+0.89 periodic 6.7 GHz methanol masers using the Hartebeesthoek 26-m radio telescope. G188.95+0.89 (S252, AFGL5180) is a radio-quiet methanol maser site that is often interpreted as precursors of ultra-compact HII regions or massive protostar sites. At least five bright spectral components were identified. The maser feature at 11.36 km s-1 was found to experience an exponential decay during the monitoring period. The millimetre continuum reveals two cores associated with the source.

Average channel capacity in anisotropic atmospheric non-Kolmogorov turbulent medium

2019 ◽  
Vol 451 ◽  
pp. 129-135 ◽  
Author(s):  
Yalçın Ata ◽  
Yahya Baykal ◽  
Muhsin Caner Gökçe
Keyword(s):  
Channel Capacity ◽  
Turbulent Medium ◽  
Average Channel Capacity

Synchronized periodic maser flares of multiple OH and CH3OH lines in G323.459–0.079

2021 ◽  
Vol 502 (4) ◽  
pp. 5658-5667
Author(s):  
G C MacLeod ◽  
Derck P Smits ◽  
J A Green ◽  
S P van den Heever
Keyword(s):  
Magnetic Field ◽  
Excited State ◽  
Central Region ◽  
Time Lags ◽  
Field Reversal ◽  
Methanol Maser ◽  
Physical Conditions ◽  
Upper Limit ◽  
Methanol Masers ◽  
Magnetic Field Reversal

ABSTRACT The first confirmed periodically varying 6.031 and 6.035 GHz hydroxyl masers are reported here. They vary contemporaneously with the 6.7 GHz methanol masers in G323.459–0.079. The 1.665 GHz hydroxyl and 12.2  GHz methanol masers associated with G323.459–0.079 are also periodic. Evidence for periodicity is seen in all features in all transitions save a single 1.665 GHz hydroxyl maser feature. Historical excited-state hydroxyl maser observations set a stricter upper limit on the epoch in which a significant accretion event occurred. The associated burst in 6.7 GHz methanol maser activity has subsided significantly while the hydroxyl transitions are brightening possibly the result of changing physical conditions in the masing cloudlets. Time lags in methanol are confirmed and may be the result of the periodic flaring propagating outward from the central region of maser activity. A possible magnetic field reversal occurred during the accretion event.

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