Abstract
view Abstract Citations (11) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Near-Infrared Photometry of the Core-Collapsed Metal-Poor Globular Cluster NGC 5946 and NGC 7099 Davidge, T. J. Abstract Moderately deep near-infrared images are used to investigate the photometric properties and spatial distribution of bright giants near the centers of the core-collapsed globular clusters NGC 5946 and NGC 7099. The former cluster is located at a low galactic latitude and is heavily reddened; nevertheless, the K, J-K color-magnitude diagram shows a well defined giant branch, with a width ±0.05 mag in J-K. Most of the observed width is due to differential reddening. The upper giant branch is relatively steep, and comparisons with less reddened clusters indicate that (1) NGC 5946 must be very metal-poor, with [Fe/H]∼-2, and (2) E (B-V)∼0.6. The distance to NGC 5946 derived using the near-infrared brightness of the giant branch tip is in excellent agreement with that computed from the V brightness of the RB if E (B-V)=0.6. The NGC 7099 giant branch terminates ∼1 mag fainter in K than the expected tip brightness. The integrated J-K color of NGC 7099 changes with radius, such that Δ(J-K)/Δ log(r)=0.05-0.09, depending on the technique used to measure colors. Similar radial variations in stellar content might be expected in NGC 5946; however, the integrated J-K color of this cluster remains constant with radius and, after removing the brightest resolved stars, a color gradient is seen that is in the opposite sense to that in NGC 7099. The relative density of bright giant branch stars also remains constant within 30 arcsec of the center of NGC 5946. Therefore, it is concluded that NGC 5946 does not contain stellar content gradients similar to those seen in NGC 7099 and other post core-collapsed clusters. Publication: The Astronomical Journal Pub Date: September 1995 DOI: 10.1086/117597 arXiv: arXiv:astro-ph/9505114 Bibcode: 1995AJ....110.1177D Keywords: GLOBULAR CLUSTERS: INDIVIDUAL: NGC 5946; GLOBULAR CLUSTERS: INDIVIDUAL: NGC 7099; STARS: GIANT; Astrophysics E-Print: To appear in The Astronomical Journal, 36 pages latex. Available as Postscript from http://www.dao.nrc.ca/DAO/SCIENCE/science.html Figures not included but available from davidge@dao.nrc.ca full text sources arXiv | ADS | data products SIMBAD (14)
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