J/ApJ/668/331 OH masers in W3(OH) (Fish+, 2007)
Structure of W3(OH) from very high spectral resolution observations of
5 centimeter OH masers.
Fish V.L., Sjouwerman L.O.
<Astrophys. J., 668, 331-347 (2007)>
=2007ApJ...668..331F 2007ApJ...668..331F
ADC_Keywords: Interstellar medium; Masers
Keywords: ISM: individual (W3(OH)) - line: profiles - magnetic fields - masers -
radio lines: ISM - stars: formation
Abstract:
Recent studies of methanol and ground-state OH masers at very high
spectral resolution have shed new light on small-scale maser
processes. The nearby source W3(OH), which contains numerous bright
masers in several different transitions, provides an excellent
laboratory for high spectral resolution techniques. We present a model
of W3(OH) based on European VLBI Network (EVN) observations of the
rotationally excited 6030 and 6035MHz OH masers taken at 0.024km/s
spectral resolution.
Description:
The European VLBI Network (EVN) was used to observe the 6030.747 and
6035.092MHz OH main-line masers in dual circular polarization in
W3(OH). Eight stations were used: the Mk II telescope at Jodrell Bank,
Effelsberg, the Onsala 25m telescope, Medicina, Torun, Noto, Darnhall,
and a single Westerbork antenna. No usable data were obtained in left
circular polarization (LCP) at 6030MHz at the Mk II telescope due to
a hardware failure.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 292 Detected 6030 and 6035MHz masers in W3(OH)
table2.dat 41 117 Zeeman pairs and associations
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See also:
J/ApJ/647/418 : Ground-state OH masers in W3(OH) study (Fish+, 2006)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [FS2007b] Spot number
5- 8 I4 MHz Freq Transition frequency (6030 or 6035)
10 A1 --- Pol [LR] Left or Right circular polarization
12- 18 F7.2 mas oRA Right Ascension offset (G1)
20- 27 F8.2 mas oDE Declination offset (G1)
29- 34 F6.2 km/s Vel LSR velocity of channel of peak emission
36- 41 F6.2 Jy Sp Peak brightness of Gaussian fit in channel of
peak emission in units of Jy/beam
43- 47 F5.3 km/s/mas Vgrad ? Velocity gradient
49- 52 I4 deg PA [-180/180]? Position angle of Vgrad (2)
54- 55 I2 --- Zg ? Zeeman group from Table 2
57 A1 --- f_[FS2007b] [fgp] Flag on [FS2007b] (3)
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Note (2): Position angle east of north in direction of increasing
line-of-sight velocity across the maser spot.
Note (3): Flag as follows:
f = Reference feature
g = Consistent with B=8.3mG, vLSR=-43.26km/s if interpreted
as a multi-transition Zeeman association
p = Unpaired maser in one transitions consistent with the central
velocity and magnetic field strength derived from a Zeeman pair
in the other transitions
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Zg Zeeman group sequential number
3 A1 --- n_Zg [d] in a Zeeman association (1)
5- 11 F7.2 mas oRA Right Ascension offset (G1) (2)
13- 20 F8.2 mas oDE Declination offset (G1) (2)
22- 25 I4 MHz Freq Frequency (6030 or 6035)
27- 32 F6.2 km/s Vel Center LSR velocity of the Zeeman pair
34- 37 F4.1 10-7T B Magnetic field, in milli-Gauss (3)
39- 41 F3.1 mas Sep Separation
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Note (1): d = See Sect. 3.3 for a discussion of this Zeeman association
Note (2): Average of the right ascension and declination offsets of the
left circular (LCP) and right circular (RCP) polarization components
of the Zeeman pair.
Note (3): Positive values indicate magnetic fields oriented in the
hemisphere pointing away from the observer.
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Global notes:
Note (G1): Centroid of Gaussian fit in channel of peak emission.
Right Ascension and Declination offsets are with respect to
02:27:03.8343, +61:52:25.300 ± 0.01". Errors range from <0.01mas
for the strongest maser spots to ∼1mas for the weakest detections.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 29-Nov-2009