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We report on measurements of parallax and proper motion for four 22 GHz water maser sources as part of the VERA Outer Rotation Curve project. All the sources show Galactic latitudes of >2° and Galactocentric distances of >11 kpc at the Galactic longitude range of 95° < l < 126°. The sources trace the Galactic warp reaching to 200–400 pc, and also the signature of the warp to 600 pc toward the north Galactic pole. The new results, along with previous results in the literature, show that the maximum height of the Galactic warp increases with Galactocentric distance. Also, we examined velocities perpendicular to the disk for the sample, and found oscillatory behavior between the vertical velocities and Galactic heights. This behavior suggests the existence of bending (vertical density) waves, possibly induced by a perturbing satellite (e.g. the passage of the Sagittarius dwarf galaxy). [ABSTRACT FROM AUTHOR]

As part our investigation into the Galactic rotation curve, we carried out Very Long Baseline Interferometry (VLBI) observations towards the star-forming region IRAS 01123+6430 using VLBI Exploration of Radio Astrometry (VERA) to measure its annual parallax and proper motion. The annual parallax was measured to be 0.151 ± 0.042 mas, which corresponds to a distance of |$D = 6.61^{+2.55}_{-1.44}\:{\rm kpc}$|⁠ , and the obtained proper motion components were |$(\mu _\alpha {\rm cos}\delta ,\, \mu _\delta) = (-1.44 \pm 0.15,\, -0.27 \pm 0.16)\:{\rm mas\:yr^{-1}}$| in equatorial coordinates. Assuming Galactic constants of |$(R_0,\, \Theta _0) = (8.05 \pm 0.45\:{\rm kpc},\, 238 \pm 14\:{\rm km\:s^{-1}})$|⁠ , the Galactocentric distance and rotation velocity were measured to be |$(R,\, \Theta) = (13.04 \pm 2.24\:{\rm kpc},\, 239 \pm 22\:{\rm km\:s^{-1}})$|⁠ , which are consistent with a flat Galactic rotation curve. The newly estimated distance provides a more accurate bolometric luminosity of the central young stellar object, |$L_{\rm Bol} = (3.11 \pm 2.86) \times 10^{3}\, L_{\odot }$|⁠ , which corresponds to a spectral type of B1–B2. Analysis of |${}^{12}{\rm{CO}}$| (J = 1–0) survey data obtained with the Five College Radio Astronomical Observatory (FCRAO) 14 m telescope shows that the molecular cloud associated with IRAS 01123+6430 consists of arc-like and linear components, which matches well a structure predicted by numerical simulation of the cloud–cloud collision phenomenon. The coexistence of arc-like and linear components implies that the relative velocity of the two initial clouds was as slow as 3– |$5\:{\rm km\, s^{-1}}$|⁠ , which meets the expected criteria of massive star formation where the core mass is effectively increased in the presence of low relative velocity (∼3–5 km s−1), as suggested by Takahira, Tasker, and Habe (2014 , ApJ, 792, 63). [ABSTRACT FROM AUTHOR]