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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742442.0, MPI für Astronomie / Publikationen_mpia
Space motions of the dwarf spheroidal galaxies Draco and Sculptor based on HST proper motions with a ~ 10 yr time baseline
Authors:Sohn, S. T.; Patel, E.; Besla, G.; van der Marel, R. P.; Bullock, J. S.; Strigari, L. E.; van de Ven, G.; Walker, M. G.; Bellini, A.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 93 (14 pp)
Audience:Not Specified
Abstract / Description:We present new proper motion (PM) measurements of the dwarf spheroidal galaxies (dSphs) Draco and Sculptor using multiepoch images obtained with the Hubble Space Telescope ACS/WFC. Our PM results have uncertainties far lower than previous measurements, even those made with the same instrument. The PM results for Draco and Sculptor are ({μ }W, {μ }N{)}{Dra}=(-0.0562+/- 0.0099, -0.1765+/- 0.0100) {mas} {{yr}}-1 and ({μ }W, {μ }N{)}{Scl}=(-0.0296+/- 0.0209, -0.1358+/- 0.0214) {mas} {{yr}}-1. The implied Galactocentric velocity vectors for Draco and Sculptor have radial and tangential components: ({V}{rad}, {V}\tan {)}{Dra}=(-88.6, 161.4)+/- (4.4, 5.6) {km} {{{s}}}-1 and ({V}{rad}, {V}\tan {)}{Scl}=(72.6, 200.2)+/- (1.3, 10.8) {km} {{{s}}}-1. We study the detailed orbital histories of both Draco and Sculptor via numerical orbit integrations. Orbital periods of Draco and Sculptor are found to be 1–2 Gyr and 2–5 Gyr, respectively, accounting for uncertainties in the Milky Way (MW) mass. We also study the influence of the Large Magellanic Cloud (LMC) on the orbits of Draco and Sculptor. Overall, the inclusion of the LMC increases the scatter in the orbital results. Based on our calculations, Draco shows a rather wide range of orbital parameters depending on the
Free Keywords:galaxies: dwarf; Galaxy: halo; Galaxy: kinematics and dynamics; proper motions
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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