Paul J. McMillan, James J. Binney
Published 2009-09-09Version 1
We re-examine the method of deprojection of proper motions, which has been used for finding the velocity ellipsoid of stars in the nearby Galaxy. This method is only legitimate if the lines of sight to the individual stars are uncorrelated with the stars' velocities. Very simple models are used to show that spurious results similar to ones recently reported are obtained when velocity dispersion decreases with galactocentric radius in the expected way. A scheme that compensates for this bias is proposed.
Comments: 5 pages, 5 figures (3 colour), MNRAS submitted
Spatial orientation and shape of the velocity ellipsoids of the Gaia DR3 giants and subgiants in the Galactic plane
ALMA Astrometry of the Objects within 0.5 pc of Sagittarius A$^\ast$
Analysis of modern astrometric catalogues in the Gaia era
![QR code for arXiv:0909.1679 [astro-ph.GA]](http://oss.arxitics.com/images/favicon.svg)