NOAO >   Observing Info >   Approved Programs >   2009B-0005

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Proposal Information for 2009B-0005


PI: James M. Nemec, Camosun College, nemec@camosun.bc.ca
Address: Physics Department, 3100 Foul Bay Road, Victoria, BC V8P5J2, Canada

CoI: Alistair Walker, Cerro Tololo Inter-American Observatory
CoI: Young-Beom Jeon, Korea Astron. & Space Science Inst.

Title: Physical Characteristics of Variable Stars in LMC Halo Globular Clusters: NGC1841

Abstract: We are proposing to continue our study of the variable stars in the globular clusters located in the halo of the Large Magellanic Cloud. Over the past two years the SMARTS 0.9-m telescope has been used to acquire exceptional sets of B,V-photometry of the variable stars in four clusters: NGC 2257, NGC 2210, NGC 1466 and Reticulum. With this proposal we are requesting time to observe NGC 1841, a remote very-open halo cluster ideally suited for observation with this telescope and badly in need of new-epoch high-precision B,V photometry. We will also observe, less frequently, the other four clusters in order to derive \it accurate periods and period-change-rates and to better define the properties of their Blazhko, LPV and other unusual variables. Archival HST and NTT images will be used to assist in dealing with the most crowded stars. The goals of our program are to establish, for the first time, \it precise and \it accurate observational characteristics (eg. light curves, pulsation periods, amplitudes, Fourier characteristics) from which can be calculated reliable physical characteristics (eg. pulsation modes, metal abundances, period change rates, luminosities, effective temperatures, and masses). With these fundamental data in hand, comparisons will be made with recent IR photometry and with the variable stars in other environments, and the stars will be used to better establish the cluster distances, to test ever-improving models of stellar evolution, and for improving our understanding of the evolution of the LMC.


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