HST Measurements of Cepheid Variables in an Inner Field of M101

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Session 24 -- The Distance Scale
Display presentation, Monday, 9, 1995, 9:20am - 6:30pm

[24.05] HST Measurements of Cepheid Variables in an Inner Field of M101

P.B. Stetson (DAO/HIA/NRC), S.M.G.~Hughes (RGO), A.~Turner, R.C.~Kennicutt (Steward), W.L.~Freedman, R.~Hill (OCIW), J.R.~Mould (MSSSO), L.~Ferrarese, H.C.~Ford (JHU/STScI), J.A.~Graham (DTM/CIW), J.G.~Hoessel (Wisconsin), G.D.~Illingworth, D.~Kelson (Lick), B.F.~Madore (IPAC), A.~Saha (STScI)

We present the results of recent observations of a field centered 1\Min7 from the core of the the nearby supergiant Sc-type spiral galaxy M101 (= NGC 5457). The data were obtained with the WFPC2 camera on the Hubble Space Telescope as part of the Key Project on the Extragalactic Distance Scale. Representative light curves for Cepheid variables detected within the field will be shown, and their period-luminosity relation will be compared with that found in an outer M101 field lying 7\Min9 from the center. This comparison will place limits on the variation of the P-L relation with metallicity, as well as refining our knowledge of the distance to this galaxy and its fellow group members --- important calibrators of the Tully-Fisher and Type-II supernova expanding-photospheres distance indicators. Color-magnitude diagrams for the field will also be shown.

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