2008/06/30 by Paul J. McMillan, James J. Binney · 92 citations
Physics and Astronomy · #Action (physics) #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Galaxy #Orbit (dynamics) #Phase space #Reference frame #Satellite #Satellite galaxy #Space (punctuation) #Stars #Stellar, planetary, and galactic studies #Torus #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.13767.x
published in Monthly Notices of the Royal Astronomical Society 390(1), 429-437 (Oxford University Press) · 10 pages, 9 figures (1 new), revisions reflect version accepted by MNRAS
arxiv created 2008/08/27 · openalex publication_date 2008/09/05 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Angle-action coordinates are used to study the relic of an N-body simulation of a self-gravitating satellite galaxy that was released on a short-period orbit within the disc of the Galaxy. Satellite stars that lie within 1.5 kpc of the Sun are confined to a grid of patches in action space. As the relic phase mixes for longer, the patches become smaller and more numerous. These patches can be seen even when the angle-action coordinates of an erroneous Galactic potential are used, but using the wrong potential displaces them. Diagnostic quantities constructed from the angle coordinates both allow the true potential to be identified, and the relic to be dated. Hence, when the full phase space coordinates of large numbers of solar-neighbourhood stars are known, it should be possible to identify members of particular relics from the distribution of stars in an approximate action space. This would then open up the possibility of determining the time since the relic was disrupted and gaining better knowledge of the Galactic potential. The availability of angle-action coordinates for arbitrary potentials is the key to these developments. The paper includes a brief introduction to the torus technique used to generate them.