CDROM/AJ/V113/P1001     NGC 147 (Han+ 1997)
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Stellar Populations in the Dwarf Elliptical Galaxy NGC 147
      M. Han, J. G. Hoessel, J. S. Gallagher III, J. Holtzman, P. B. Stetson,
      J. Trauger, G. E. Ballester, C. Burrows, J. Clarke, D. Crisp,
      R. Griffiths, C. Grillmair, J. Hester, J. Krist, J. R. Mould, P. Scowen,
      K. Stapelfeldt, A. Watson, and J. Westphal
      <1997, AJ, 113, 1001>
      =1997AJ....113.1001H
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Abstract:
  Deep V and I CCD images in a central and an outer field of the Local
  Group dwarf elliptical galaxy NGC 147 have been obtained with the Wide
  Field and Planetary Camera-2 (WFPC2) on board of the Hubble Space
  Telescope. The color-magnitude diagram shows a number of interesting
  features, including a well defined red giant branch (RGB), a red
  horizontal branch (HB), a strong red clump, and a small number of
  extended asymptotic giant branch (EAGB) stars. A mean distance modulus
  of (m-M)_0=24.39 is derived based on both the HB and the RGB tip
  brightness. The metallicity [Fe/H] as determined from the RGB color has
  a mean value of -0.91 in the central field, and -1.0 in the outer
  field; and the outer field shows a weak tendency of increasing
  metallicity with galactocentric radius. A metallicity dispersion is
  also present in the galaxy, and it shows a clear radial variation in
  the sense that a larger dispersion is seen at smaller radii. The small
  population of EAGB stars indicates the presence of intermediate-aged
  (several Gyr) stars in the galaxy, while the absence of the main
  sequence stars with M_V<1 shows that star formation ceased at least 1
  Gyr ago. The distribution of the EAGB stars indicates that the younger
  stars are more centrally concentrated than the majority of older
  stars. A similar age gradient is also implied by the relative
  distribution of the HB stars, which appear to be more populous at
  larger radii. These results are considered within the context of
  theoretical models for the evolution of dwarf elliptical
  galaxies. (Copyright) 1997 American Astronomical Society.


File Summary:
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File Name    Lrecl    Records   Explanations
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table2a.dat     46      78421   NGC 147 - inner field photometry
table2b.dat     46      38203   NGC 147 - outer field photometry
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Byte-by-byte Description of file: table2a.dat table2b.dat
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   Bytes Format  Units   Label      Explanations
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   1- 8   F8.2   pix     X         *X pixel coordinate
   9-16   F8.2   pix     Y         *Y pixel coordinate
  17-24   F8.3   mag     V          V magnitude
  25-31   F7.3   mag     e_V        Error in V
  32-39   F8.3   mag     I          I magnitude
  40-46   F7.3   mag     e_I        Error in I
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Notes for file: table2a.dat table2b.dat
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X, Y:
  The coordinate system is defined by simply stacking up the
  contiguous fields of the 4 chips in each field (see HST/WFPC2
  Handbook v3.0), and defining the central joining point to be
  at (800,800).  X and Y are in units of WF pixels.
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(End)                                             Lee Brotzman [ADS] 09-Apr-1997