2019/02/19 by Alexandra L. Gregory, Alexandra L Gregory, Michelle Collins +9 · 25 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Blue dwarf #Brown dwarf #Classical mechanics #Dwarf galaxy #Dwarf galaxy problem #Dwarf spheroidal galaxy #Galaxy #Interacting galaxy #Kinematics #Local Group #Physics #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stz518
published in Monthly Notices of the Royal Astronomical Society 485(2), 2010-2025 (Oxford University Press) · Accepted for publication in MNRAS. 17 pages, 13 figures. Updated to match journal version
openalex publication_date 2019/02/19 · arxiv created 2019/03/04 · arxiv updated 2019/03/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We present new FLAMES+GIRAFFE spectroscopy of 36 member stars in the isolated Local Group dwarf spheroidal galaxy Tucana. We measure a systemic velocity for the system of |vTuc = 216.7-2.8+2.9| km s−1, and a velocity dispersion of |σ v,Tuc = 14.4-2.3+2.8| km s−1. We also detect a rotation gradient of |\frac\rm dvr\rm dχ = 7.6+4.2-4.3| km s−1 kpc−1, which reduces the systemic velocity to |vTuc = 215.2-2.7+2.8| km s−1 and the velocity dispersion to |σ v,Tuc = 13.3-2.3+2.7| km s−1. We perform Jeans modelling of the density profile of Tucana, using the line-of-sight velocities of the member stars. We find that it favours a high central density consistent with ‘pristine’ subhaloes in Λ cold dark matter, and a massive dark matter halo (∼1010 M⊙) consistent with expectations from abundance matching. Tucana appears to be significantly more centrally dense than other isolated Local Group dwarfs, making it an ideal laboratory for testing dark matter models.