NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T01:10:30 PDT
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For refcode 1993AJ....106..964L:
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1993AJ....106..964L STELLAR POPULATIONS IN THE DWARF ELLIPTICAL GALAXY NGC 185 MYUNG GYOON LEE AND WENDY L. FREEDMAN Carnegie Observatories, 813 Santa Barbara Street, Pasadena, California 91101 Electronic mail: I: mglee@ociw.edu, I: wendy@ociw.edu BARRY F. MADORE NASA/IPAC Extragalactic Database Infrared Processing and Analysis Center, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91101 Electronic mail: I: barry@ipac.caltech.edu Received 1993 March 12; revised 1993 April 28 ABSTRACT BVRI CCD photometry of ~5300 stars in the central (2.2' X 3.5') area of the dwarf elliptical galaxy NGC 185 in the Local Group is presented. The color-magnitude diagrams of NGC 185 show three distinct stellar populations: (1) a strong red giant branch (RGB) population, the tip of which is found to be at I_TRGB_ = 20.3+/-02 mag, and (V-I)_TRGB_ = 1.95+/-0.05, (2) an asymptotic giant branch (AGB) located above the tip of the RGB, and (3) a small number of young stars having blue to yellow colors. The reddening of the bright foreground stars has been determined using the (B-V) - (V-I) diagram to be E(B-V) = 0.19+/-0.03 mag. The distance has been estimated from the I magnitude of the tip of the RGB, giving (m-M)_0_ = 23.96+/-0.21 mag for A_I_ = 0.38 mag, corresponding to 620+/-60 kpc. The mean metallicity of the RGB stars has been determined using the median color of the RGB stars at M_I_ = -3.5 mag, (V-I)_-3.5,0_ = 1.727 mag: giving a mean metallicity of [Fe/H]= -1.23+/-0.16 dex. The dispersion in color at M_I_ = -3.5 mag is {DELTA}(V-I)_-3.5_ = 0.12 mag, implying a metallicity dispersion of -1.6 < [Fe/H] < -0.9 dex. Surface photometry of the area within R = 50" is also presented, showing that colors get rapidly bluer inside R~10". A V luminosity function for the blue stars has been derived, the slope of which is very similar to that for other nearby galaxies. The AGB stars extend to M_bol_ ~ -5.0 mag, and most of the AGB stars above the tip of the RGB are likely to belong to an intermediate-age population. The bolometric luminosity function of the red giant stars in NGC 185 is found to be very similar to that of M32.
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