NOAO >   Observing Info >   Approved Programs >   2010A-0265

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Proposal Information for 2010A-0265


PI: Lucas 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 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 (P-L) 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. We request a total of 3 nights on WIYN to achieve three goals: (i) obtain more precise periods and phases for the variables, in support of ongoing HST near-IR observations; (ii) continue the search for long period Cepheids in this galaxy; (iii) tie the existing Gemini observations to the Sloan magnitude system, to obtain accurate magnitudes and colors for these important variables.


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NOAO >   Observing Info >   Approved Programs >   2010A-0265

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