2017/09/25 by Alis J. Deason, Vasily Belokurov, S. E. Koposov +1 · 22 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Gamma-ray bursts and supernovae #Geography #Kinematics #Lernaean Hydra #Photometry (optics) #Physics #Sky #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stx2528
published in Monthly Notices of the Royal Astronomical Society 473(2), 2428-2433 (Oxford University Press) · 5 pages, 5 figures. MNRAS Letters accepted
arxiv created 2017/09/25 · openalex publication_date 2017/09/26 · arxiv updated 2017/11/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the kinematic properties of the Eastern Banded Structure (EBS) and Hydra I overdensity using exquisite proper motions derived from the Sloan Digital Sky Survey (SDSS) and Gaia source catalogue. Main sequence turn-off stars in the vicinity of the EBS are identified from SDSS photometry; we use the proper motions and, where applicable, spectroscopic measurements of these stars to probe the kinematics of this apparent stream. We find that the EBS and Hydra I share common kinematic and chemical properties with the nearby Monoceros Ring. In particular, the proper motions of the EBS, like Monoceros, are indicative of prograde rotation (Vϕ ∼ 180–220 km s−1), which is similar to the Galactic thick disc. The kinematic structure of stars in the vicinity of the EBS suggests that it is not a distinct stellar stream, but rather marks the ‘edge’ of the Monoceros Ring. The EBS and Hydra I are the latest substructures to be linked with Monoceros, leaving the Galactic anti-centre a mess of interlinked overdensities which likely share a unified, Galactic disc origin.