2020/10/27 by Y. Xu, C. Liu, H. Tian +7 · 39 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Disc #Dwarf galaxy #Galactic Center #Galactic plane #Galactic tide #Galaxy #Milky Way #Sky #Spiral galaxy #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/abc2cb
published in The Astrophysical Journal 905(1), 6 (IOP Publishing) · 31pages, 23figures, ApJ accepted
arxiv created 2020/10/27 · openalex created_date 2020/11/09 · openalex publication_date 2020/12/01 · arxiv updated 2020/12/16 · openalex updated_date 2026/08/06
Abstract The recent discovery of a spiral feature in the Z − V Z phase plane in the solar neighborhood implies that the galactic disk has been remarkably affected by a dwarf galaxy passing through it some hundreds of millions of years ago. Using 429,500 Large Sky Area Multi-Object Fibre Spectroscopic Telescope K giants stars, we show that the spiral feature exists not only in the solar vicinity but it also extends to about 15 kpc from the Galactic center and then disappears beyond this radius. Moreover, we find that when the spiral features in a plot of V ϕ as a function of position in the Z − V Z plane at various galactocentric radii are remapped to the R − Z plane, the spiral can explain well the observed asymmetric velocity substructures. This is evidence that the phase spiral features are the same as the bulk motions found in previous work as well as this work. Test particle simulations and N -body simulations show that an encounter with a dwarf galaxy a few hundred million years ago will induce a perturbation in the galactic disk. In addition, we find that the last impact of Sgr dSph can also contribute to the flare. As a consequence of the encounter, the distribution function of disk stars at a large range of radii is imprinted by the gravitational perturbation.