Vertical Structure and Kinematics of the Galactic Outer Disk

Abstract

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

Accepted for publication in PASJ; 4 figures & 6 tables

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Cited by in corpus (3)

• Precise radio astrometry and new developments for the next generation of instruments
• Parameters of the Galactic Spiral Density Wave from Masers with Parallax Errors Less Than 10%
• Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes