TY - JOUR
T1 - Photometric Detection of Multiple Populations in Globular Clusters Using Integrated Light
AU - Bowman, William P.
AU - Pilachowski, Catherine A.
AU - Zee, Liese Van
AU - Winans, Amanda
AU - Ciardullo, Robin
AU - Gronwall, Caryl
N1 - Funding Information:
We are grateful to the anonymous referee for her/his critical and constructive comments and for helping to improve the overall quality of this study. We thank Enrico Vesperini, Alex Hagen, Joanna Bridge, and Owen Boberg for their help, insight, and thoughtful comments as we prepared this manuscript. The 0.9 m telescope is operated by WIYN Inc. on behalf of a Consortium of partner Universities and Organizations (seehttp://www.noao.edu/0.9m for a list of the current partners). WIYN is a joint partnership of the University of Wisconsin at Madison, Indiana University, Yale University, and the National Optical Astronomical Observatory. W.P.B. and C.A.P. gratefully acknowledge support from the Daniel Kirkwood endowment at Indiana University. The Institute for Gravitation and the Cosmos is supported by the Eberly College of Science and the Office of the Senior Vice President for Research at the Pennsylvania State University. This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France. The original description of the VizieR service was published in A&AS 143, 23. This research also made use of the USNOFS Image and Catalog Archive operated by the United States Naval Observatory, Flagstaff Station (http://www.nofs. navy.mil/data/fchpix/). This research has made use of NASA’s Astrophysics Data System Bibliographic Services.
Funding Information:
IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.
Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/10
Y1 - 2017/10
N2 - We investigate the multiple stellar populations of the globular clusters (GCs) M3, M5, M13, and M71 using g' and intermediate-band CN- λ 3883 photometry obtained with the WIYN 0.9 m telescope on Kitt Peak. We find a strong correlation between red giant stars CN-g' colors and their spectroscopic sodium abundances, thus demonstrating the efficacy of the two-filter system for stellar population studies. In all four clusters, the observed spread in red giant branch CN-g' colors is wider than that expected from photometric uncertainty, confirming the well-known chemical inhomogeneity of these systems. M3 and M13 show clear evidence for a radial dependence in the CNband strengths of its red giants, while the evidence for such a radial dependence of CN strengths in M5 is ambiguous. Our data suggest that the dynamically old, relatively metal-rich M71 system is well mixed, as it shows no evidence for chemical segregation. Finally, we measure the radial gradients in the integrated CN-g' color of the clusters and find that such gradients are easily detectable in the integrated light. We suggest that photometric observations of color gradients within GCs throughout the Local Group can be used to characterize their multiple populations, and thereby constrain the formation history of GCs in different galactic environments.
AB - We investigate the multiple stellar populations of the globular clusters (GCs) M3, M5, M13, and M71 using g' and intermediate-band CN- λ 3883 photometry obtained with the WIYN 0.9 m telescope on Kitt Peak. We find a strong correlation between red giant stars CN-g' colors and their spectroscopic sodium abundances, thus demonstrating the efficacy of the two-filter system for stellar population studies. In all four clusters, the observed spread in red giant branch CN-g' colors is wider than that expected from photometric uncertainty, confirming the well-known chemical inhomogeneity of these systems. M3 and M13 show clear evidence for a radial dependence in the CNband strengths of its red giants, while the evidence for such a radial dependence of CN strengths in M5 is ambiguous. Our data suggest that the dynamically old, relatively metal-rich M71 system is well mixed, as it shows no evidence for chemical segregation. Finally, we measure the radial gradients in the integrated CN-g' color of the clusters and find that such gradients are easily detectable in the integrated light. We suggest that photometric observations of color gradients within GCs throughout the Local Group can be used to characterize their multiple populations, and thereby constrain the formation history of GCs in different galactic environments.
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U2 - 10.3847/1538-3881/aa84b0
DO - 10.3847/1538-3881/aa84b0
M3 - Article
AN - SCOPUS:85031086057
SN - 0004-6256
VL - 154
JO - Astronomical Journal
JF - Astronomical Journal
IS - 4
M1 - 131
ER -