Astron. J., 124, 811-827 (2002/August-0)
The dwarf irregular/Wolf-Rayet galaxy NGC 4214. I. A new distance, stellar content, and global parameters.
DROZDOVSKY I.O., SCHULTE-LADBECK R.E., HOPP U., GREGGIO L. and CRONE M.M.
Abstract (from CDS):
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 Wide Field Planetary Camera 2 and Near-Infrared Camera and Multi-Object Spectrometer (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 NICMOS 2 camera. 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 barlike structure, and a relatively low surface 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, H I 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 to be [Fe/H]≃-1.7 dex, with a large internal abundance spread characterized by σint([Fe/H])~1 dex.
Galaxies: Dwarf - Galaxies: Individual: NGC Number: NGC 4214 - Galaxies: Stellar Content
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