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Proper motion of OH maser in G34.3+0.2

Proper motion of OH maser in G34.3+0.2. Li Guo, Xingwu Zheng, Bo Zhang, Xi Chen Shanghai Observatory, China Nanjing university, China kent-gl@shao.ac.cn. Outline. Introduction Observations and results Analysis Future work. Introduction.

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Proper motion of OH maser in G34.3+0.2

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  1. Proper motion of OH maser in G34.3+0.2 Li Guo, Xingwu Zheng, Bo Zhang, Xi Chen Shanghai Observatory, China Nanjing university, China kent-gl@shao.ac.cn

  2. Outline • Introduction • Observations and results • Analysis • Future work

  3. 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 provides 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.

  4. 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

  5. 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

  6. 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°14’ 58.85 , • 128 spectral channels -> velocity spacing of 0.176km/s • Phase reference : LSR velocity 58.8km/s in 1667MHz RCP

  7. 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 the residual fringe rate • Calibrated visibilities were Fourier transformed and de-convolved using IMAGR with cell-size 3*6 mas

  8. Results • All OH maser features of the first epoch, 120 maser spots in all

  9. moving star bow shock model

  10. Results • Epoch1:49 maser spots; Epoch 2:39

  11. Results • 25 maser features are conformed for proper motions • The averaged proper motion • +0.99mas/yr in R.A. • -1.87mas/yr in DEL

  12. Results

  13. 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

  14. Future work • Proper motions of All the OH maser spots will be calculated soon

  15. Thanks for your attentions!

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