NOAO >   Observing Info >   Approved Programs >   2011A-0555

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Proposal Information for 2011A-0555


PI: Lucas M. Macri, Texas A&M University, lmacri@tamu.edu
Address: Dept. of Physics and Astronomy, 4242 TAMU, College Station, TX 77843, United States

CoI: Samantha Hoffmann, Texas A&M University

Title: Cepheids and Long-Period Variables in NGC 4258

Abstract: We propose to observe Cepheids and long period variables in NGC 4258. This galaxy serves as the “anchor” or first rung in the Extragalactic Distance Scale thanks to a very precise and accurate geometric distance estimate based on VLBI maser observations. We imaged NGC 4258 with Gemini from 2004 to 2007 and discovered a large number of long-period Cepheids, extending the upper period range of the previously-existing HST Period-Luminosity relation from 45 to 150 days. In addition, we discovered numerous long-period variables (LPVs) with periods up to 900 days. These variables have the potential to be excellent distance indicators in the near-infrared, which is highly relevant for the JWST era. Last year we were awarded three nights with WIYN to continue our study and the observations were very successful. Encouraged by the results, we request an additional 3 nights to continue the search for additional long-period variables and to refine the periods and phases of the already-known ones. The WIYN data will provide critical support to recently obtained HST WFC3/IR observations.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2011A-0555

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