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East Asian VLBI activities

East Asian VLBI activities. VSOP/VSOP2. KVN. CVN. VERA & JVN. Parallax measurements of H2O maser source beyond 5 kpc with VERA. Mizusawa-VERA observatory, NAOJ Mareki Honma & VERA project member. Contents. Based on astrometry of S269 (at ~5kpc), we present the results on Parallax

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East Asian VLBI activities

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  1. East Asian VLBI activities VSOP/VSOP2 KVN CVN VERA & JVN

  2. Parallax measurements of H2O maser source beyond 5 kpc with VERA Mizusawa-VERA observatory, NAOJ Mareki Honma & VERA project member

  3. Contents Based on astrometry of S269 (at ~5kpc), we present the results on • Parallax • Proper motions • Galactc rotation velocity at S269

  4. Star Forming Region S269 S269 : Massive SFR toward anti-center regions Near-IR view of S269

  5. VERA array VERA : VLBI array dedicated to astrometry new technology : dual-beam phase referencing Mizusawa Iriki Max. baseline : 2300 km Ishigaki-jima Ogasawara 2004~ observations started

  6. S269 H2O maser 0.4 mas linear structure with velocity gradient Accretion disk around YSO ? • Intensity200 Jy • Reference： J0613+1305, (0.7 deg separation) Cross-power spectrum

  7. Parallax measurement East-West motion for 1 yr North-South motion for 1 yr • Motions of S269 H2O maser 1yr position π：189 +/-16 μas D：5.30 +/- 0.44 kpc World record for smallest parallax !

  8. S269in the Milky Way ~30 kpc • S269 ～5.3 kpc c.f. R0 ~ 8 kpc Ready to perform Galaxy-scale astrometry Sun

  9. S 269 proper motion S269 motion with respect to LSR (V_l, V_b) = (-4.6, -4.1) km/s much smaller than galactic rotation (c.f. ~200 km/s) > similar galactic rotation velocity at the Sun and at S269

  10. Galactic rotation velocity at S269 • Rotation velocity determination from V_l obs. V_l = -5 +/-5 km/s Vc_S269 /Vc_sun = 1.00 +/- 0.03 (accuracy 3%！) • Radial velocity is consistent with the above results Radial vel. Tangential vel. Vr , V_l Vc_S269 /Vc_Sun

  11. Constraint on the rotation curve • Strong constraint from one objects Flat rotation curve out to 13 kpc

  12. Summary • We have successfully measured the parallax and proper motions of S269 with VERA. • Galactic rotation velocity at S269 is the same to that at LSR within 3%. > Strong constraint on outer rotation curve ---these results demonstrate power of high-precision astrometry !

  13. Announcement • VERA will be open to international use from this observational season (2006/07) • Dual-beam mode at 22 GHz will be open. • Call for proposal will be in Oct 2006, and deadline will be the end of October. --- If you are interested, please contact us !

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