Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/research/workshops/2013/maserworkshop2013/talks/12-James_Chibueze.pdf Дата изменения: Fri Jun 21 05:42:43 2013 Дата индексирования: Sat Mar 1 09:58:31 2014 Кодировка: Поисковые слова: massive stars

Water Maser Bipolar Outflow Associated SMA1 Massive Young Stellar Object of NGC 6334I(N)

James O. Chibueze East Asian ALMA Regional Center, National Astronomical Observatory of Japan.
Collaborators: Imai, H., Omodaka, T., Handa, T., Nagayama, T., Sunada, K., Nakano, M., Hirota, T., & Kamezaki, T. A Neapolitan of Masers: Variability, Magnetism and VLBI 20 - 22 May 2013


NGC 6334I(N) - Introduction
* The youngest region of the Cat Paw nebula. (earliest phase of MSF) * At a distance of ~1.7 kpc (~1.2 kpc based on our trigonometric parallax results) * Associated with CH3OH and H2O masers (Buether et al. 2005) * Associated with shocked gas (Persi et al. 2005) * Estimated total mass of ~ 2200 M (Hunter et al. 2006)

Composite image of NGC 6334 in the mid-infrared. MSX bands A (8.3 m), D (14.7 m) and E (21.3 m). The radio HII regions and mid- and far-infrared sources are labeled according to the adopted identification.


Motivation: Based on Brogan et al. (2009) SMA 1.3 mm continuum objects, SMA 1-7, some associated with H2O masers detected with VLA (blue crossses and arrows pointing to their spectra)

Brogan et al. (2009)


Observations
· · · · · · · · · Japanese VLBI Network (JVN) Observations K-band, ~ 22GHz Target source: NGC 6334I(N) Phase reference source: J1713-3418 Bandpass calibrator: NRO530 Number of epochs: 10 From February, 2010 ~ April, 2012 Angular resolution: 1.2 mas at 22 GHz Velocity resolution: 0.21 km/s

Data Reduction/Analysis
· * Standard AIPS data reduction procedure, Self-calibration (relative position of maser features wrt the bright maser spot) · * Normal phase referencing (to obtain the absolute position of the reference maser spot, in order to compare with VLA continuum map). · * Maser maps, and proper motion identification (identified in 3 or more epochs and some in 2 epochs for cases of velocity or position isolation)


Results

1.3mm SMA map, VLA H2O masers Brogan et al. (2009)

JVN H2O masers map


C

A: SMA 1.3 mm continuum (solid lines), VLA 7 mm continuum of SMA 1a-d and VLA3 (grey scale and solid lines) B: VLA 1.7mm continuum (solid lines), 3.6 cm continuum (dashed lines), 1.3 cm continuum (gray scale), CH3OH masers (yellow ellipse), H2O masers (colored crosses) C: JVN H2O maser map (top), superposed image of the maser distribution in SMA1b on it 1.3 cm VLA continuum map (bottom)

B

A Brogan et al. (2009)


HW2

HW3d
* Maser proper motions in SMA1b tracing a bipolar outflow structure with a driving source most probably located at R.A. (J2000) = 17h 20m 55.195s .1909, and declination (J2000) = - 35d45'03''.70 (derive from the model in the next slide) * Mean proper motion of 11.6 km/s and extending through 720 AU * Dynamical timescale of ~ 295 years. * Bipolar structure aligns well with the outflow report in previous papers (Rodriguez et al. 2007: dashed line across SMA1b)

(Rodriguez et al. 2007)


Position/Velocity Variance and Covariance Matrix Analysis (Bloemhof 1993)


Expanding flow model of the maser spatio-kinematics

(Least-square method involving Levenburg-Marquart minimization technique) NP: number of free parameters (= 4) Nm: number of proper motion data (= 23)

Assumption: Each maser feature is radially moving away from a common originating point (near 0,0) of the outflow with Vexp (i). Radial expanding motion of maser feature

( uix - v 0x ) rix + ( uiy - v 0 y ) riy + ( uiz - v 0 z ) z Vexp (i) = ri

iz


Derived Expansion Velocity of Individual Maser Features

Most of the expansion velocities were positive as espected, 4 negative expansion velocity could be as a result of infall, turbulence or some error in the model fitting.


Summary
1. We detected outflow activity in SMA1b, indicating that this source is internally excited by a massive young stellar object. 2. The bipolar motions of the H2O masers indicate the presence of a YSO-jet system in SMA1b. 4. ALMA & EVLA observations will be helpful to explore the physical conditions of this object.