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Color and population gradients in the core of the postcollapse globular cluster M30

Piotto, Giampaolo and King, Ivan R. and Djorgovski, S. (1988) Color and population gradients in the core of the postcollapse globular cluster M30. Astronomical Journal, 96 (6). pp. 1918-1924. ISSN 0004-6256. doi:10.1086/114937.

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We have developed a new technique for seeking color gradients in multicolor CCD images of a globular cluster. Application of this technique to M30 confirms the radial color gradient reported by others. The B - V and V - R colors show linear gradients, when plotted against log r, that are many times their statistical errors. In the radial range ~ 3-100 arcsec, the B - V and V - R colors increase outwards by about (0.18 ± 0.015) mag/dex and (0.09 ± 0.01) mag/dex, respectively. Color-magnitude arrays of the central region show that the Balmer-line strength that accompanies the central blueness is due to an increased proportion of blue-horizontal-branch starlight in the center. This excess does not appear to be statistically significant in terms of star numbers, even though the color gradient is so highly significant. The authors are divided among themselves as to whether the color and spectrum gradients observed here and in other clusters are due only to random statistical fluctuations, or whether they might have a physical significance.

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Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1988 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 14 June 1988; revised 25 August 1988. Based on observations collected at the European Southern Observatory, La Silla, and the Cerro Tololo Inter-American Observatory. We are indebted to the staffs of ESO and CTIO for their expert help during our observing runs. S. D. wishes to acknowledge partial support from the California Institute of Technology, and G. P. partial support from the Fondazione A. Gini. This work was also supported in part by contract no. NASA5-28086.
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Fondazione Aldo GiniUNSPECIFIED
Issue or Number:6
Record Number:CaltechAUTHORS:20190806-153202765
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97683
Deposited By: Tony Diaz
Deposited On:07 Aug 2019 16:54
Last Modified:16 Nov 2021 17:33

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