Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.atnf.csiro.au/research/masermeeting/web_papers/333_Voronkov.pdf Äàòà èçìåíåíèÿ: Fri Mar 23 00:37:51 2007 Äàòà èíäåêñèðîâàíèÿ: Sun Dec 23 11:36:50 2007 Êîäèðîâêà:

T H E AU S T R A L I A T E L E S C O P E C A M PA I G N T O S T U DY SOUTHERN CLASS I METHANOL MASERS
M.A.Voronkov (ATNF), K.J.Brooks, A.M.Sobolev, S.P.Ellingsen, A.B.Ostrovskii, J.L.Caswell contact: Maxim.Voronkov@csiro.au

Introduction
Class I methanol masers (e.g. 9.9, 25, 104 GHz) Maser spots are spread around the protostar location


Avoid strong infrared sources and ultra-compact HII regions There is a lack of high resolution data to answer which phenomenon in star-forming regions these masers are associated with


Conclusions
The 9.9- and 104-GHz masers brighter than 0.1 and 0.5 Jy, respectively, are rare. Models suggest that they require more energetic conditions (higher temperatures and densities) The 25-GHz masers are found in a large number of sources In 343.12-0.06, these masers were detected in one spot (B) only and showed association with the brightest knot of H emission We were unable to reproduce the relative intensities of all observed transitions in a single model. Parameter gradients in the shocked gas? If yes, the length scale is less than 300 AU
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Pumped by collisions with hydrogen and helium


Need searches of various class I masers to develop a pumping model


the spectrum of this offset component is plotted in red
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A molecular hydrogen image of the source obtained by Brooks et al. (2003, ApJ, 594, L131):

For more details see Voronkov et al., 2006, MNRAS, 373, 411

ATCA 9.9 GHz survey

Only one maser at this frequency was known prior to this work (W33-Met)
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Positions and literature suggest a possible association with ionization shocks, except 343.12-0.06 where there is a clear association with an outflow


ATCA 25 GHz (J=5) search
Masers detected in all class I transitions observed so far


Observed 102 targets 54 masers, 8 marginal, and 5 sources with just a broad line emission These masers were believed to be rare and only 4 masers were known prior to this work
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Most observations were done in the director's time no position measurement for most sources


Fluxes do not correlate with other class I masers




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Source name 331.132-0.24 343.12-0.06 W33-Met 19.61-0.23

Absolute position (J2000) VLSR F R.A. Dec. (km s ) (Jy) 16:10:59.47(1) 51:50:23.9(2) 91.16 1.9(1) 16:58:16.460(2) 42:52:25.73(3) 31.56 9.5(3) 18:14:10.897(3) 17:55:58.42(8) 32.72 4.3(1) 18:27:37.475(2) 11:56:37.77(8) 41.24 3.3(1)

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Observed 48 independent positions broad line sources


3 new masers, no

Spectra of Spot B:

The source harbours a highly collimated jet-driven molecular outflow ATCA has been used to observe 12 class I maser transitions at 9.9, 25 (a series from J=2 to J=9), 84, 95, 104 GHz in a short period of time One spot (B) is active in all observed transitions, while 5 others are active at 84 and 95 GHz only (spots E and D are marginal detections at 84 GHz)









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Only one maser at this frequency was known prior to this work (W33-Met)


343.12-0.06 (IRAS 16547-4247)

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Observed 69 targets two new masers, 5 marginal detections and 3 broad line sources
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Mopra 104 GHz survey



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Are the main focus of studies since the discovery of the bright and widespread maser transition at 6.7 GHz


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Pumped by infrared radiation


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Maser sites usually have established association with millimeter and infrared sources, and sometimes with ultra-compact HII regions


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Class II methanol masers (e.g. 6.7, 12 GHz)

Absolute position (J2000) VLSR F R.A. Dec. (km s ) (Jy) 13:12:36.921(4) 62:33:35.46(4) 33.08 8.9(1) 13:12:36.772(4) 62:33:37.00(4) 34.77 1.5(1) 331.34-0.35 16:12:26.413(2) 51:46:20.57(3) 65.40 2.3(2) 16:12:26.413(3) 51:46:20.57(5) 65.92 1.7(2) 333.562-0.025 16:21:08.803(1) 49:59:47.89(3) 39.70 5.0(1) 16:21:08.748(2) 49:59:48.81(3) 39.88 1.8(1) 16:21:08.814(1) 49:59:48.17(3) 39.23 1.4(1) 345.00-0.22 17:05:11.114(1) 41:29:19.83(2) 27.97 9.4(1) 17:05:11.110(3) 41:29:20.4(1) 28.87 0.7(1) 7.6(1) 351.24+0.67 17:20:18.325(1) 35:54:41.26(2) 2.54 17:20:23.643(1) 35:55:02.59(4) 0.73 6.0(4) 351.78-0.54 17:26:42.862(1) 36:09:03.35(3) 6.84 3.5(2) 17:26:42.451(2) 36:09:17.37(9) 4.26 1.7(2) 17:26:42.481(3) 36:09:17.4(1) 2.33 2.2(2) 1.72 2.5(2) 17:26:42.448(2) 36:09:15.8(1)
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Source name 305.36+0.20

Three southern spots in this source (two are active at 84 and 95 GHz only) show clear association with a jetdriven molecular outflow Their velocities are close to that of the molecular core within which the jet is embedded. This fact supports the idea that some class I masers reside in the interface regions of outflows. There are indications that other 9.9-GHz masers found in the project could be associated with the ionization shocks The 9.9- and 104-GHz spectra of 343.12-0.06 contain a very narrow spike ( 0.03 km s ) which has a brightness temperature greater than 5.3 10 and 2.0 10 K at 9.9 and 104 GHz, respectively

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New 25 GHz masers with accurate positions

Spots A-C clearly trace the shocked gas delineated by the H 2.12 m emission and their velocities are close to that of the molecular core they are associated with the interface region