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