Using atomic hydrogen (H I) data from the VLA Galactic Plane Survey, we measure the H I terminal velocity as a function of longitude for the first quadrant of the Milky Way. We use these data, together with our previous work on the fourth Galactic quadrant, to produce a densely sampled, uniformly measured, rotation curve of the northern and southern Milky Way between 3 kpc < R < 8 kpc. We determine a new joint rotation curve fit for the first and fourth quadrants, which is consistent with the fit we published in McClure-Griffiths & Dickey and can be used for estimating kinematic distances interior to the solar circle. Structure in the rotation curves is now exquisitely well defined, showing significant velocity structure on lengths of ∼200 pc, which is much greater than the spatial resolution of the rotation curve. Furthermore, the shape of the rotation curves for the first and fourth quadrants, even after subtraction of a circular rotation fit shows a surprising degree of correlation with a roughly sinusoidal pattern between 4.2 < R < 7 kpc.
Funding
Australian Research Council
History
Publication title
The Astrophysical Journal
Volume
831
Issue
2
Article number
124
Number
124
Pagination
1-8
ISSN
0004-637X
Department/School
School of Natural Sciences
Publisher
Univ Chicago Press
Publication status
Published
Place of publication
1427 E 60Th St, Chicago, USA, Il, 60637-2954
Rights statement
Copyright 2016 The American Astronomical Society
Socio-economic Objectives
280120 Expanding knowledge in the physical sciences