proper motion of oh maser in g34.3+0.2
DESCRIPTION
Proper motion of OH maser in G34.3+0.2. Li Guo, Xingwu Zheng, Bo Zhang, Xi Chen Shanghai Observatory, China Nanjing university, China [email protected]. Outline. Introduction Observations and results Analysis Future work. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
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Proper motion of OH maser in G34.3+0.2
Li Guo, Xingwu Zheng, Bo Zhang, Xi Chen
Shanghai Observatory, China
Nanjing university, China
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Outline
• Introduction
• Observations and results
• Analysis
• Future work
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Introduction
• OH masers probing the environments of high-mass star-forming regions (SFRs)
• Bright >1Jy• Zeeman splitting, the magnetic field strength and
line-of-sight directions • Linear polarization direction and fraction provide
s additional information about the 3D alignment of the magnetic field
• Velocity field of many points around the central star-> using the velocity of emission of maser features.
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Introduction
• G34.3+0.2 observations and theoretical models
• Observations: radio continuum and atomic and molecular lines, 4 HII regions (components A B C D) found in the complex
• 3 models: moving star bow shock model; champagne flow model; stellar wind model; high gas velocity
• Low signal strength limits the resolution of observations of thermal emission so that those of the non-thermal maser emission may be useful
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Observation
• 2 epochs of G34.3+0.2• The first epoch• Time: 3 June, 1995, 5.5hrs on source• Sites: NRAO VLBA 10 antennas• Freq : 1665MHz 1667MHz• Polarization: LCP RCP• 250kHz pass-band centered on Vlsr=60km/s• Array phase center a2000 = 18h 53m 18.651s, d2000 = 01°
14’ 58.08 • 256 spectral channels -> velocity spacing of 0.176km/s• Phase reference : LSR velocity 58.8km/s in 1667MHz RCP
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Observation
• The second epoch• Time: 1 Feb, 2001, 4.2hrs on source• Sites: NRAO VLBA 10 antennas• Freq : 1665MHz 1667MHz• Polarization: LCP RCP• 125kHz pass-band centered on Vlsr=58km/s• Array phase center a2000 = 18h 53m 18.67s, d2000 = 01°1
4’ 58.85 , • 128 spectral channels -> velocity spacing of 0.176km/s• Phase reference : LSR velocity 58.8km/s in 1667MHz RCP
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Data processing
• RR LL auto-polarization mode Socorro, New Mexico
• Parallatic angle, amplitude corrections• Fringe rates, delay and Doppler shift corrections• Fringe fitting of the phase reference to determine th
e residual fringe rate• Calibrated visibilities were Fourier transformed and
de-convolved using IMAGR with cell-size 3*6 mas
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Results
• All OH maser features of the first epoch, 120 maser spots in all
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moving star bow shock model
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Results• Epoch1:49
maser spots; Epoch 2:39
-100-50050100-600
-400
-200
0
200
400
600
R.A. Offset (mas)
DE
C.
Off
set
(mas
)
58.2
58.4
58.6
58.8
59
59.2
-100-50050100-600
-400
-200
0
200
400
600
R.A. Offset (mas)
DE
C. O
ffset
(mas
)
58
58.2
58.4
58.6
58.8
59
59.2
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Results• 25 maser features
are conformed for proper motions
• The averaged proper motion
• +0.99mas/yr in R.A.• -1.87mas/yr in
DEL
-1000100-500
-400
-300
-200
-100
0
100
200
300
400
R.A. Offset (mas)
DE
C.
Off
set
(mas
)
58
58.05
58.1
58.15
58.2
58.25
58.3
58.35
58.4
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Results
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Analysis
• About 40 OH maser spots have been found in the cluster near the apex
• All OH maser spots are found to be well aligned along the ionization front
• Distributions of all maser spots and proper motion of maser spots near the apex maybe show the consistency with the moving star bow shock model
• More detailed work
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Future work
• Proper motions of All the OH maser spots will be calculated soon
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Thanks for your attentions!