Proper Motion of the Sextans Dwarf Galaxy from Subaru Suprime-Cam Data

Abstract

We have measured the absolute proper motion of the Sextans dwarf spheroidal galaxy using Subaru Suprime-Cam images taken at three epochs, with a time baseline of ~ 10 years. We astrometrically calibrate each epoch by constructing distortion-correction maps from the best available Subaru Suprime-Cam dithered data sets and from Gaia DR1 positions. The magnitude limit of the proper-motion study is V ~ 24. The area covered is 26.7 x 23.3 arcmin, which is still within the core radius of Sextans. The derived proper motion is (mu_a, mu_d) = (-0.409 +/- 0.050, -0.047 +/- 0.058) mas/yr. The direction of motion is perpendicular to the major axis of the galaxy. Our measurement, combined with radial velocity and distance from the literature, implies a low eccentricity orbit, with a moderate inclination to the Galactic plane, and a period of 3 Gyr. Sextans is now some 0.4 Gyr away from its pericenter ( r_peri ~ 75 kpc), moving toward its apocenter (r_apo ~ 132 kpc). Its orbit is inconsistent with membership to the vast polar structure of Galactic satellites.

14 pages, 14 figures, 4 tables. Accepted for publication in MNRAS

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Cited by in corpus (5)

• Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital properties with a massive Large Magellanic Cloud
• Proper Motions, Orbits, and Tidal Influences of Milky Way Dwarf Spheroidal Galaxies
• The Milky Way's Disk of Classical Satellite Galaxies in Light of Gaia DR2
• A New Proper Motion Determination of Leo I
• A 3D view of dwarf galaxies with Gaia and VLT/FLAMES II. The Sextans dwarf spheroidal