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J/ApJ/541/841       UBV photometry and ages of Trapezium systems    (Abt+, 2000)
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The maximum age of Trapezium systems.
    Abt H.A., Corbally C.J.
   <Astrophys. J. 541, 841 (2000)>
   =2000ApJ...541..841A
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ADC_Keywords: Stars, double and multiple ; Photometry, UBV ; Reddening ;
              Stars, distances
Keywords: binaries: visual - open clusters and associations: general -
          stars: fundamental parameters

Abstract:
    We sought to determine the maximum age of Trapezium systems by
    studying possible trapezium systems that were selected independently
    of their occurrence in H II regions. We started with the unpublished
    catalog by Allen, Tapia & Parrao (1977RMxAA...3..119A) of all the
    known visual systems having three or more stars in which the maximum
    separation is less than 3.0 times the minimum separation. Their
    catalog has 968 such systems whose most frequent primary type is F,
    which does not describe young systems. With a CCD on the Kitt Peak
    0.9m telescope we obtained UBV frames for 265 systems accessible with
    our equipment on Kitt Peak. The frames were used to obtain UBV
    photometry for about 1500 stars with an accuracy of 0.04mag between
    V=7 and 14mag. Also these frames were used to obtain astrometry with
    an accuracy of +/-0.015{deg} in position angle and +/-0.01" in
    separation. For the brightest star in each system we obtained a
    spectral type to determine the distance and reddening to the system.

File Summary:
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 FileName      Lrecl  Records   Explanations
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ReadMe            80        .   This file
table3a.dat       85      265   Conclusions about the Possible Trapezium Systems
table3b.dat      125     1592   Observational Data
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See also:
   I/134 : Trapezium Multiple Systems (Salukvadze, 1978)

Byte-by-byte Description of file: table3a.dat
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   Bytes Format Units   Label     Explanations
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   1-  8  A8    ---     [AC2000b] Trapezium group name ([AC2000b] Trap NNN)
  11- 12  I2    h       RAh       Right Ascension (1900)
  14- 17  F4.1  min     RAm       Right Ascension (1900)
      19  A1    ---     DE-       Sign on the Declination (1900)
  20- 21  I2    deg     DEd       Declination (1900)
  23- 24  I2    arcmin  DEm       Declination (1900)
  26- 37  A12   ---     OName     Other name (ADS  ... = no ADS name)
  40- 67  A28   ---     Concl     Conclusions about the group
  69- 73  F5.2  mag     E(B-V)    ? Reddening
      75  A1    ---   f_E(B-V)    [:?A] Flag on E(B-V) (1)
  79- 82  F4.1  mag     DMod      ? Distance modulus
      84  A1    ---   f_DMod      [?A] Flag on DMod (1)
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Note (1): Flags:
     : = uncertain value
     ? = unknown value
     A = refers to star 'A'
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Byte-by-byte Description of file: table3b.dat
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   Bytes Format Units   Label     Explanations
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   1-  8  A8    ---     [AC2000b] Trapezium group name ([AC2000b] Trap NNN)
  10- 11  I2    ---     ID1       Identification number for Figure 1
  13- 14  A2    ---     ID2       Identification letter from other sources
  16- 20  F5.2  mag     Vmag      ? V band magnitudes
  22- 26  F5.2  mag     B-V       ? B-V color
  28- 32  F5.2  mag     U-B       ? U-B color
  34- 51  A18   ---     MKClass   MK classification
  53- 56  I4    yr      ODate     Date of earlier astrometric measurements
  58- 61  I4    yr      ORange    ? If present, indicates measurements obtained
                                   from ODate to ORange
  63- 67  A5    ---   n_OSep      ? Star pair that OSep and OPA refer
  68- 73  F6.2  arcsec  OSep      ? Old angular separation relative to
                                   the first star
      75  A1    ---   f_OSep      [v:] Flag on OSep (1)
  77- 81  F5.1  deg     OPA       ? Old position angle relative to
                                   the first star
  83- 85  A3    ---   f_OPA       [v orb] Flag on OPA (1)
  87- 94  F8.3  yr      Date      Date of observations from this work
  96- 99  A4    ---   n_Sep       ? Star pair that Sep and PA refer
 102-107  F6.2  arcsec  Sep       ? This work's angular separation relative
                                   to the first star
 110-115  F6.2  deg     PA        ? This work's position angle relative
                                   to the first star
 117-129  A13   ---     Concl     Conclusions about the physical association
                                   of each component
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Note (1): Flags
      v = variable
      : = uncertain measurement
      orb = orbit
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History:
    From ApJ electronic version
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(End)                    Greg Schwarz [AAS], Patricia Bauer [CDS]    05-Dec-2000