CDROM/PASP/V106/P486    ubyHbeta Photometry of Melotte 66 (Anthony-Twarog+ 1994)
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vbyHbeta CCD Photometry of Melotte 66: A Disk Analog of Omega Centauri?
      Barbara J. Anthony-Twarog, Bruce A. Twarog, & Marian Sheeran
      <1994, PASP, 106, 486>
      =1994PASP..106..486A
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Abstract:
  A CCD study of the peculiar open cluster, Melotte 66, on the
  vbyHBeta system is presented.  The V,(b-y) color-magnitude diagram of
  this metal-deficient, old disk cluster confirms the anomalous features
  found in photographic BV studies and extends the main sequence to V =
  20.  The main sequence exhibits a (b-y) color range significantly
  larger than expected from photometric errors alone; the (b-y) colors
  are correlated with Hbeta implying that the dispersion is real and is
  not the result of variable reddening across the cluster.  The m1
  indices for the turnoff stars imply a spread in [Fe/H] too small to
  explain the color range.  Though the subgiant region is poorly defined,
  the region above the turnoff in the Hertzsprung gap is richly populated
  by a group of "yellow stragglers" whose membership is confirmed by
  radial star counts and radial velocities.  The giant branch is richly
  populated but shows a smaller spread in color at a given V than one
  would expect from the turnoff region.  More important, the giants
  exhibit a large scatter in m1, in contradiction with the turnoff
  observations.  Various explanations for these observations are
  discussed, including CN variations among the giants triggered by either
  binary evolution or rapid rotation among the main-sequence stars.

File Summary:
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File Name    Lrecl    Records    Explanations
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table3.dat      99        520    Photometric indices for Mel 66 stars
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Byte-by-byte Description of file: table3.dat
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   Bytes Format  Units      Label    Explanations
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   1- 5	  I5      ---       Haw      Hawarden identification number
   6-10   I5      ---       ID       Identification number
  11-17   F7.2    pix       X        X pixel position
  18-24   F7.2    pix       Y        Y pixel position
  25-33   F9.3    mag       V        V magnitude (apparent)
  34-40   F7.3    mag       e_V      standard error of the mean V magnitude
  41-47   F7.3    mag       b-y      (b-y) color
  48-54   F7.3    mag       e_b-y    standard error of the mean (b-y) color
  55-61   F7.3    mag       m1       m1 index
  62-68   F7.3    mag       e_m1     standard error of the mean m1 index
  69-75   F7.3    ---       Hbeta    []? H beta index
  76-82   F7.3    ---       e_Hbeta  []? standard error of the mean H-Beta index
  83-84   2X      ---       ---      Blank
  85-87   I3      ---       Ny       Number of y frames
  88-90   I3      ---       Nb       Number of b frames
  91-93   I3      ---       Nv       Number of v frames
  94-96   I3      ---       Nw       Number of H Beta wide frames
  97-99   I3      ---       Nn       Number of H Beta narrow frames
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(End)                                             Lee Brotzman [ADS] 21-May-1994