Browsing by Author "Kuehn, Charles A., III"

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    RR Lyrae in LMC Globular Clusters
    (2009) Kuehn, Charles A., III; Smith, H. A.; Taylor, L.; McClellan, R. E.; Catelan, Marcio; Looper, K.; Pritzl, B. J.; De Lee, N.
    We present preliminary results from a study of five globular clusters located in the Large Magellanic Cloud. The goal of this project is to carry out a large, systematic study of the behavior of RR Lyrae stars in Oosterhoff-intermediate globular clusters. The LMC is an ideal target for a study of this sort as it contains Oosterhoff-intermediate clusters as well as Oo-I/II clusters. We seek to answer three main questions. 1.) Are there double-mode RR Lyrae stars (RRd) in Oo-intermediate clusters and if so how do their properties compare to RRd stars in Oo-I/II clusters? 2.) How do the positions of RR Lyrae stars on the Bailey diagram differ between stars in Oo-intermediate clusters compared to those in Oo-I/II clusters? 3.) How do the Fourier decomposition parameters of RR Lyrae stars change when going from Oo-I/II clusters to Oo-intermediate ones? We present Oosterhoff classifications and sample light curves for some of the clusters in our study and discuss their Fourier parameters and resulting physical properties. We also discuss the implications of our findings on the nature of the Oosterhoff dichotomy and what that implies about Milky Way formation....
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    RR Lyrae in LMC Globular Clusters: Insights into the Oosterhoff Phenomenon and Milky Way Formation
    (2011) Kuehn, Charles A., III; Smith, H. A.; Catelan, Marcio; Taylor, L.; McClellan, R. E.; Looper, K.; DeLee, N.; Pritzl, B. J.
    We present results from a study of RR Lyrae stars in five globular clusters located in the Large Magellanic Cloud. The goal of this study was to look at the behavior and properties of RR Lyrae stars in Oosterhoff-intermediate globular clusters and compare them to RR Lyrae in Oosterhoff I and II clusters. New BVI photometric observations of these clusters were obtained with the SMARTS consortium telescopes and with the SOAR 4-meter telescope. We present light curves and Fourier properties for the RR Lyrae stars in our study as well as physical properties for these stars derived from their Fourier parameters. We compare these physical properties to those of RR Lyrae in Milky Way halo globular clusters and discuss implications for Milky Way halo formation....
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    Variable Stars in the LMC Globular Cluster NGC 1754
    (2006) Kuehn, Charles A., III; Taylor, L.; Smith, H. A.; Catelan, Marcio; Pritzl, B. J.; De Lee, N.
    We have used BVI observations taken with the SMARTS 1.3m telescope and with the SOAR telescope to identify variable stars in the vicinity of the old LMC cluster NGC 1754. We present light curves and periods for the variables and classify the variables according to type. The probability that the RR Lyrae stars found in the neighborhood of NGC 1754 actually belong to the cluster is discussed. Unlike most globular clusters of the Milky Way halo, many of the old star clusters of the LMC have Oosterhoff intermediate properties. The Oosterhoff classification of field and cluster RR Lyrae stars near NGC 1754 is considered. We thank the NSF for partial support of this research....