• DOI:10.1093/mnras/stt1522
• Corpus ID: 59148135

The Wobbly Galaxy : kinematics north and south with RAVE red-clump giants

@article{Williams2013TheWG,
  title={The Wobbly Galaxy : kinematics north and south with RAVE red-clump giants},
  author={M. E. Williams and Matthias Steinmetz and James Binney and Arnaud Siebert and Harry Enke and Beno{\^i}t Famaey and Ivan Minchev and Roelof de Jong and Corrado Boeche and Kenneth C. Freeman and Olivier Bienaym{\'e} and J. Bland-Hawthorn and Brad K. Gibson and Gerard Gilmore and Amina Helmi and Georges Kordopatis and U. Munari and Julio F. Navarro and Quentin A. Parker and W. Reid and George Seabroke and S Sharma and Alessandro Siviero and Fred G. Watson and Rosemary F. G. Wyse and Toma{\vz} Zwitter},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2013},
  volume={436},
  pages={101-121}
}

• M. Williams, M. Steinmetz, +23 authors T. Zwitter
• Published 11 February 2013
• Physics, Geology
• Monthly Notices of the Royal Astronomical Society

The RAdial Velocity Experiment survey, combined with proper motions and distance estimates, can be used to study in detail stellar kinematics in the extended solar neighbourhood (solar suburb). Using 72 365 red-clump stars, we examine the mean velocity components in 3D between 6 <R <10 kpc and -2 <Z <2 kpc, concentrating on north-south differences. Simple parametric fits to the (R, Z) trends for Vφ and the velocity dispersions are presented. We confirm the recently discovered gradient in mean Galactocentric radial velocity, VR, finding that the gradient is marked below the plane (δ/δR = -8 km s-1 kpc-1 for Z <0, vanishing to zero above the plane), with a Z gradient thus also present. The vertical velocity, VZ, also shows clear, large-amplitude (|VZ| = 17 km s-1) structure, with indications of a rarefaction-compression pattern, suggestive of wave-like behaviour. We perform a rigorous error analysis, tracing sources of both systematic and random errors. We confirm the north-south differences in VR and VZ along the line of sight, with the VR estimated independent of the proper motions. The complex three-dimensional structure of velocity space presents challenges for future modelling of the Galactic disc, with the Galactic bar, spiral arms and excitation of wave-like structures all probably playing a role.