Water Masers in NGC7538 Region Osamu KAMEYA　 （Mizusawa VERA Observatory,　NAOJ）,　VERA　team　　　　 VERA stations　 NGC7538 JHK image Ohja et al 2004

VERA:VLBI Exploration of Radio Astrometry 1. VERA system and status VERA:VLBI Exploration of Radio Astrometry Stations: four Baseline: 1000-2300km Diameter：20m Obs bands: 2, 8, 22, 43GHz VERA stations and baseline length by geodetic obs on Dec. 17, 2004 Mizu- sawa Iriki 41mm/yr Ogasawara Ishigaki- jima 66mm/yr Unit: mm

>> Cancel out the fluctuation of the atmosphere 1. VERA system and status Dual beam system　 >>　Cancel out the fluctuation of the atmosphere >> 10μarcsec accuracy (target) for position relative to reference sources 　Maser　　　　　　　Maser QSO

VERA can measure parallax of masers In the whole Galaxy. Maser VERA 1AU Galactic Center 10% accuracy @10kpc 10% accuracy 0.1% accuracy @100pc Sun

Maser Test observations for several years >> succeeded in measuring parallaxes for some maser sources （e.g.　 Next talk by Honma ） >> open the common use observation for everyone in the world (from this winter) Details : Next talk by Honma VERA 1AU Galactic Center 10% accuracy 10% accuracy @10kpc 0.1% accuracy @100pc Sun

2. Activity of NGC7538 Region CasA－NGC7538 Molecular Cloud Complex Distance=2.7kpc　（OB　association） NGC7538（S158) S159 100pc @3kpc S156 S157 CasA CO　J=1-0　（Kameya et al.1990） Bell Labo　6m

Activity of NGC7538 Region NGC7538 JHK image Ohja et al 2004

Activity of NGC7538 Region NGC7538 IRS1-3 IRS9 IRS11 NGC7538 JHK image Ohja et al 2004 NGC7538 IRS1-3 IRS9 IRS11

Ultra compact HII regions VLA 15cm Kameya et al. 1990 Sandel et al. 2004 JCMT 850μ Ultra compact HII regions VLA 15cm Kameya et al. 1990 Kameya et al. 1986 CO outflow

NGC7538 IRS1, 9, 11 Methanol 6.7GHz methanol maser IRS9 & S 1. MERLIN & EVN 2004 Nov 2. EVN 2004 Dec Pestalozzi etal. 2006 A&A 448, L57-L60 NGC7538 IRS1, 9, 11 Methanol

H2O maser IRS1(N) IRS9(E) IRS11(S) Molecular Outflow NGC7538 H2O Masers （Kameya et al. 1990） NMA（1987.5） IRS1(N) IRS9(E) Molecular Outflow IRS11(S)

H2O maser IRS11(S) Molecular Outflow NGC7538 H2O Masers （Kameya et al. 1990） NMA（1987.5） IRS11(S) Molecular Outflow

H2O maser IRS11(S) H2O 1977 Feb27-28 Only one VLBI map for IRS11 Genzel et al. 1978 H2O　1977 Feb27-28 Only one VLBI map for IRS11 IRS11(S)

3.VERA observation of H2O masers of NGC 7538 1. 2005yr103d ( April 13th )　19h-6hUT Recording mode: GEO1D mode 16MHz-2bit-2ch Recorder　1000　（256Mbps）　 CepA VS J2302+6405 CepA VS NGC7538N＆S 　　　2 beam separation: ~2degree 2. 2006yr 208d　(July 27th) 13h-22hUT Recording mode: VERA7MM mode 16MHz-2bit-16ch Recorder　2000　（1Gbps） 　　CepA VS J2302+6405  

Results of VERA S(IRS11) NGC7538 N&S water masers Kameya et al. 1990 　　　　Vlsr=-67km/s component is disappeared.   NGC7538 N&S　 water masers 　 Cross powser spectrum NGC7538S　H2O maser cross power spectrum　　 CepA　water masers Cross powser spectrum

Results of VERA Mapping of S (IRS11） 2005 105day -53.3 ,-53.9 -53.3 -53.9 -49.3,-61.7,-65.1 -56.0   -61.4 　-61.6　-61.7 　-56.7　-56.9 　 (0,0)の座標（1950.0）=（23h11m36. s03±0.05s、 　　　　　　　　　　　　　　61°10’30“.35±0.35”） V_lsr(km/s) Jy/Beam RA offset (mas) DEC offset (mas) -4.93E+01 7.40E+00 1.61E+03 -1.52E+03 -5.31E+01 1.25E+01 -9.66E-02 -7.06E-02 -5.33E+01 3.98E+01 -6.06E-02 -5.26E-02 -5.35E+01 7.47E+01 -3.00E-02 -2.82E-02 -5.37E+01 1.03E+00 -9.20E-03 -8.40E-03 -5.39E+01 1.12E+02 0.00E+00 -5.41E+01 9.17E+01 -2.10E-01 1.82E-02 -5.43E+01 5.27E+01 5.82E-02 4.90E-02 -5.56E+01 4.03E+00 7.04E+01 5.08E+01 -5.58E+01 3.88E+00 5.09E+01 -5.60E+01 1.96E+00 -6.15E+01 1.93E+01 1.51E+03 -1.49E+03 -6.17E+01 2.09E+01 -6.51E+01 1.31E+01 1.62E+03 4.19E+00 2.75E+00 2.02E+00 2.95E+00 2.71E+00 1.94E+00 2.18E+01 2.80E+03 -1.90E+03 -5.62E+01 2.8954 1.52E+03 -1.50E+03 3.26E+00 -65.1 --61.7 -61.7 -49.3,

Results of VERA Mapping of S (IRS11） 2006 208day -52.3 -54.3 -64.8 -56.3   -61.4 　-61.6　-61.7 (0,0)の座標（1950.0）=（23h11m36. s03±0.05s、 　　　　　　　　　　　　　　61°10’30“.35±0.35”） -64.8 -64.8

Results of VERA (S) Molecular Outflow Results （Mapping） Y -53.3 ,-53.9 -54.3 -65.1 --54.6 　-54.8 　-54.9 　-55.1 -55.3 　-55.5 　　　　Y -61.7 -56.0 -56.3 -49.3, -64.8   -61.4 　-61.6　-61.7 　-56.7　-56.9 　 Kameya et al. 1990 NMA　H2O　1987 May 9 Kameya et al. 1990b VLA　1989 April Ultra compact HII region Genzel et al. 1978 VLBI H2O　1977 Feb27-28 Molecular Outflow

Results of VERA N(IRS1) NGC7538N H2O maser cross power spectrum Kameya et al. 1990   　Vlsr=-82、-48km/s components are　disappeared. NGC7538N　H2O maser cross power spectrum　　

Results of VERA (N) Molecular Outflow Results （Mapping） X -60.4 S？   X -59.8 -70.9、-71.18、-72.4 --57.7 Molecular Outflow Kameya et al. 1990 NMA　H2O　1987 May 9

4. Summary and Conclusion VERA status VERA will open the common use observations for astronomers in the world from this winter. Details : Next talk by Honma NGC7538 Region Most detailed H2O maser distribution of N(IRS1-3) and S(IRS11) of NGC7538 region has been obtained by two- epoch VLBI observations by VERA. The global distributions of masers are not changed for 30years. Each region associate with the high dense cores, IR source, Outflow, Ultra-compact HII region, H2O, OH, methanol, and the other masers. Future Works VLBI Observations of NGC7538 Region can make clear the dynamics of each star forming region (N&S). Distance measurement for Cep A H2O maser using VERA. Distance measurement for NGC7538 using VERA.