Browsing by Author "Alonso, M. Victoria"

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    HST proper motions on the far side of the Galactic bar-data
    (2023) Soto, Mario; Kuijken, Konrad; Rich, R. Michael; Clarkson, William, I; Castellon, Jose Luis Nilo; Fernandez-Trincado, Jose G.; Ramos, Rodrigo Contreras; Kunder, Andrea; Baravalle, Laura D.; Alonso, M. Victoria; Simion, Iulia T.; Johnson, Christian, I; Vieira, Katherine
    This is the third paper in a series that attempts to observe a clear signature of the Galactic bar/bulge using kinematic observations of the bulge stellar populations in low foreground extinction windows. We report on the detection of & SIM;100 000 new proper motions in four fields covering the far side of the Galactic bar/bulge, at negative longitudes. Our proper motions have been obtained using observations from the Advance Camera for Surveys (ACS), on board of the Hubble Space Telescope (HST), with a time-baseline of 8-9 years, which has produced accuracies better than 0.5 mas yr(-1) for a significant fraction of the stellar populations with F814W < 23 mag. Interestingly, as shown in previous works, the Hess diagrams show a strikingly similar proper motion distribution to fields closer to the Galactic center and consistent with an old stellar population. The observed kinematics point to a significant bulge rotation, which seems to predominate even in fields as far as l & SIME; -8 & DEG;, and is also reflected in the changes of the velocity ellipsoid in the l, b plane as a function of distance.