scholarly journals Survey of bipolar outflows and methanol masers in the C32S ($2-1)$ and C34S (2-1) lines in the Northern sky

1999 ◽  
Vol 139 (2) ◽  
pp. 257-275 ◽  
Author(s):  
G. M. Larionov ◽  
I. E. Val'tts ◽  
A. Winnberg ◽  
L. E.B. Johansson ◽  
R. S. Booth ◽  
...  
Keyword(s):  
Bipolar Outflows ◽  
Methanol Masers

Mapping of bipolar outflows and methanol masers in the CS(2-1)line

2001 ◽  
Vol 45 (5) ◽  
pp. 331-338
Author(s):  
G. M. Larionov ◽  
V. G. Promyslov ◽  
I. E. Val'tts
Keyword(s):  
Bipolar Outflows ◽  
Methanol Masers

scholarly journals Identification of Class I Methanol Masers with Objects of Near and Mid-Infrared Bands and the Third Version of the Class I Methanol Maser (MMI) Catalog

2012 ◽  
Vol 8 (S287) ◽  
pp. 280-281
Author(s):  
Olga Bayandina ◽  
Irina Val'tts ◽  
Grigorii Larionov
Keyword(s):  
Galactic Plane ◽  
Short Wave ◽  
Class I ◽  
Young Stellar Objects ◽  
Bipolar Outflows ◽  
Stellar Objects ◽  
Mid Infrared ◽  
Dark Clouds ◽  
The Third ◽  
Methanol Masers

AbstractAn identification has been conducted of class I methanol masers with 1) short-wave infrared objects EGO (extended green objects) - tracer bipolar outflow of matter in young stellar objects, and 2) isolated pre-protostellar gas-dust cores of the interstellar medium which are observed in absorption in the mid-infrared in the Galactic plane. It is shown that more than 50% of class I methanol masers are identified with bipolar outflows, considering the EGO as bipolar outflows (as compared with the result of 22% in the first version of the MMI catalog that contains no information about EGO). 99 from 139 class I methanol masers (71%) are identified with SDC. Thus, it seems possible that the MMI can be formed in isolated self-gravitating condensations, which are the silhouette of dark clouds - IRDC and SDC.

OH 1720-MHz lines as tracers of bipolar outflows in the vicinity of Class I methanol masers

2012 ◽  
Vol 56 (7) ◽  
pp. 536-552 ◽  
Author(s):  
I. D. Litovchenko ◽  
O. S. Bayandina ◽  
A. V. Alakoz ◽  
I. E. Val’tss ◽  
G. M. Larionov ◽  
...  
Keyword(s):  
Class I ◽  
Bipolar Outflows ◽  
Methanol Masers

scholarly journals Milliarcsecond structure of methanol masers in L1206 and GL2789

2002 ◽  
Vol 206 ◽  
pp. 163-166
Author(s):  
Maxim A. Voronkov ◽  
Vyacheslav I. Slysh
Keyword(s):  
Velocity Gradient ◽  
Linear Structure ◽  
Circumstellar Disks ◽  
Bipolar Outflows ◽  
Star Forming ◽  
Star Forming Regions ◽  
Brightness Temperatures ◽  
Maser Line ◽  
Interferometric Study ◽  
Methanol Masers

We report results of EVN interferometric study of two star-forming regions L1206 and GL2789 in the brightest methanol maser line at 6.7 GHz. Using measured absolute positions both methanol masers were identified with protostars which are sources of bipolar outflows. Both masers consist of several maser spots, with some of them being aligned in a linear structure with velocity gradient probably delineating edge-on circumstellar disks. We estimated the radii of such disks to be 140 AU and 280 AU (or 700 AU for the whole structure treated as a disk) for L1206 and GL2789 respectively. The brightness temperatures of the most intense features in L1206 and GL2789 are at least 1.1 × 1010 K and 1.4 × 109K respectively.

scholarly journals The fine spatial structure of methanol masers as an evidence in support of their connection with bipolar outflows

2002 ◽  
Vol 206 ◽  
pp. 199-202
Author(s):  
Vyacheslav I. Slysh ◽  
Irina E. Val'tts ◽  
Sergei V. Kalenskii
Keyword(s):  
Spatial Structure ◽  
Brightness Temperature ◽  
Molecular Clouds ◽  
Angular Resolution ◽  
Bipolar Outflows ◽  
High Brightness ◽  
Border Line ◽  
Molecular Outflows ◽  
Methanol Masers ◽  
The Moment

We studied class I methanol masers in the transition 70 − 61A+ at the frequency 44 GHz with the VLA. The observations on the VLA were made with the angular resolution 0.1, which was the highest at the moment. It was shown that the masers consist of chains of unresolved spots located on curved lines or arcs. The length of such arcs is from 20 to 1000 AU and the brightness temperature of the strongest masers exceeds 3.6×108 K. The observed location of maser spots is in agreement with their position at the border line between molecular outflows and surrounding molecular clouds. The high brightness temperature implies that the maser condensations have enhanced abundance of methanol due to evaporation of methanol from the surface of dust grains. The mass of maser condensations is less than 4×10−5 M⊙ and corresponds to planetary masses.

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.

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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