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Author Hosek, Matthew W. (Jr.) ♦ Lu, Jessica R. ♦ Anderson, Jay ♦ Ghez, Andrea M. ♦ Morris, Mark R. ♦ Clarkson, William I.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ GALAXIES ♦ GALAXY NUCLEI ♦ LIMITING VALUES ♦ MASS ♦ ORBITS ♦ PROPER MOTION ♦ SEGREGATION ♦ SIMULATION ♦ SPACE ♦ STARS ♦ TELESCOPES
Abstract At a projected distance of ∼26 pc from Sgr A*, the Arches cluster provides insight into star formation in the extreme Galactic center (GC) environment. Despite its importance, many key properties, such as the cluster’s internal structure and orbital history, are not well known. We present an astrometric and photometric study of the outer region of the Arches cluster ( R > 6.″25) using Hubble Space Telescope WFC3IR. Using proper motions, we calculate membership probabilities for stars down to F153M = 20 mag (∼2.5 M {sub ⊙}) over a 120″ × 120″ field of view, an area 144 times larger than previous astrometric studies of the cluster. We construct the radial profile of the Arches to a radius of 75″ (∼3 pc at 8 kpc), which can be well described by a single power law. From this profile we place a 3 σ lower limit of 2.8 pc on the observed tidal radius, which is larger than the predicted tidal radius (1–2.5 pc). Evidence of mass segregation is observed throughout the cluster, and no tidal tail structures are apparent along the orbital path. The absence of breaks in the profile suggests that the Arches has not likely experienced its closest approach to the GC between ∼0.2 and 1 Myr ago. If accurate, this constraint indicates that the cluster is on a prograde orbit and is located in front of the sky plane that intersects Sgr A*. However, further simulations of clusters in the GC potential are required to interpret the observed profile with more confidence.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-11-01
Publisher Place United States
Journal Astrophysical Journal
Volume Number 813
Issue Number 1


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