Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry

Abstract

We present stellar proper motions in the Galactic bulge from the Sagittarius Window Eclipsing Extrasolar Search (SWEEPS) project using ACS/WFC on HST. Proper motions are extracted for more than 180,000 objects, with >81,000 measured to accuracy better than 0.3 mas/yr in both coordinates. We report several results based on these measurements: 1. Kinematic separation of bulge from disk allows a sample of >15,000 bulge objects to be extracted based on >6-sigma detections of proper motion, with <0.2% contamination from the disk. This includes the first detection of a candidate bulge Blue Straggler population. 2. Armed with a photometric distance modulus on a star by star basis, and using the large number of stars with high-quality proper motion measurements to overcome intrinsic scatter, we dissect the kinematic properties of the bulge as a function of distance along the line of sight. This allows us to extract the stellar circular speed curve from proper motions alone, which we compare with the circular speed curve obtained from radial velocities. 3. We trace the variation of the {l,b} velocity ellipse as a function of depth. 4. Finally, we use the density-weighted {l,b} proper motion ellipse produced from the tracer stars to assess the kinematic membership of the sixteen transiting planet candidates discovered in the Sagittarius Window; the kinematic distribution of the planet candidates is consistent with that of the disk and bulge stellar populations.

71 pages, 30 figures, ApJ Accepted

References in corpus (14)

• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation
• Modelling the Galactic bar using OGLE-II Red Clump Giant Stars
• Ground-Based CCD Astrometry with Wide Field Imagers. I. [Observations just a few years apart allow decontamination of field objects from members in two Globular clusters.]
• Transiting extrasolar planetary candidates in the Galactic bulge
• The Bulge Radial Velocity Assay (BRAVA): I. Techniques and a Rotation Curve
• The Long Bar in the Milky Way. Corroboration of an old hypothesis
• Displacement of the Sun from the Galactic Plane
• Evidence of a Metal Rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid
• Clues to the Metallicity Distribution in the Galactic Bulge: Abundances in OGLE-2007_BLG-349S
• Proper Motion Dispersions of Red Clump Giants in the Galactic Bulge: Observations and Model Comparisons
• Proper Motions in the Galactic Bulge: Plaut's Window
• Mapping stellar kinematics across the Galactic bar: HST measurements of proper motions in 35 fields
• ChaMPlane Discovery of Candidate Symbiotic Binaries in Baade's and Stanek's Windows

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