The Dwarf Irregular/Wolf-Rayet Galaxy NGC 4214: I. A New Distance, Stellar Content, and Global Parameters

Abstract

We present the results of a detailed optical and near-IR study of the nearby star-forming dwarf galaxy NGC 4214. We discuss the stellar content, drawing particular attention to the intermediate-age and/or old field stars, which are used as a distance indicator. On images obtained with the Hubble Space Telescope WFPC2 and NICMOS instruments in the equivalents of the V , R, I, J and H bands, the galaxy is well resolved into stars. We achieve limiting magnitudes of F814W ≈ 27 in the WF chips and F110W ≈ 25 in the NIC2. The optical and near-infrared color-magnitude diagrams confirm a core-halo galaxy morphology: an inner high surface-brightness young population within ∼ 1.5 (∼ 1 kpc) from the center of the galaxy, where the stars are concentrated in bright complexes along a bar-like structure; and a relatively lowsurface-brightness, field-star population extending out to at least 8 (7 kpc). The color-magnitude diagrams of the core region show evidence of blue and red supergiants, main-sequence stars, asymptotic giant branch stars and blue loop stars. We identify some candidate carbon stars from their extreme near-IR color. The field-star population is dominated by the “red tangle”, which contains the red giant branch. We use the I-band luminosity function to determine the distance based on the tip-of-the-red-giant-branch method: 2.7 ± 0.3 Mpc. This is much closer than the values usually assumed in the literature, and we provide revised distance dependent parameters such as physical size, luminosity, Hi mass and star-formation rate. From the mean color of the red giant branch in V and I, we estimate the mean metal abundance of this population as [Fe/H] ' −1.7 dex, with a large internal abundance spread characterized by σint([Fe/H]) ≈ 1 dex. Subject headings: nearby galaxies: dwarf galaxies (NGC 4214): distance moduli: stellar content Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., Under NASA contract NAS 5-26555 Astronomical Institute, St.Petersburg State University,

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Cite this paper

@inproceedings{Drozdovsky2002TheDI, title={The Dwarf Irregular/Wolf-Rayet Galaxy NGC 4214: I. A New Distance, Stellar Content, and Global Parameters}, author={Igor O. Drozdovsky and Regina E. Schulte-Ladbeck and Laura Greggio and Mary M. Crone}, year={2002} }