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J/A+A/314/448   UBV photometry of a blue straggler in NGC 2354 (Lapasset+, 1996)
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Discovery of an eclipsing blue straggler in NGC 2354
      Lapasset E., Ahumada J.
     <Astron. Astrophys. 314, 448 (1996)>
     =1996A&A...314..448L      (SIMBAD/NED BibCode)
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ADC_Keywords: Binaries, eclipsing ; Stars, blue ; Photometry, UBV
Keywords: stars: binaries: close - stars: binaries: eclipsing -
          stars: blue stragglers - stars: evolution -
          galaxy: open clusters and associations: individual: NGC 2354

Abstract:
    A photometric search for variable stars among the blue stragglers (BS)
    in southern open clusters of old and intermediate age led to the
    discovery of one eclipsing binary BS in NGC 2354. The star D266 is 1.5
    magnitudes brighter than the cluster turn-off while its angular
    distance to the cluster center is about seven tenths of the estimated
    cluster radius. This star was observed for several nights and a total
    of 422 UBV measurements were obtained. The coverage of the orbital
    cycle was almost completed, a period of 0.6388228 days was determined,
    and finally the first light curves of this eclipsing variable star
    were obtained. They show the typical characteristics of an EB-class
    close binary with minima about 0.4 and 0.1 magnitudes deep. The
    photometric analysis by means of the Wilson-Devinney code allowed to
    define a set of ten possible solutions for assumed values of the
    mass-ratio between 0.2 and 5.0. Two minima of the quality-of-fit
    function for q=0.30 and q=3.0 indicate the best solutions we could
    obtain. Regardless of the value of q, the following features could be
    established: a) both components are very close to the critical contact
    lobes and both detached or semidetached configurations fit the light
    curves in an acceptable way; b) the temperature difference between the
    components is one of the highest among this type of stars; c) the
    primary component always remains in the BS zone of the cluster
    colour-magnitude diagram. If we assume that D266 is a member of NGC
    2354, we may conclude that mass-exchange between the components of
    this system is the most probable cause of its present BS state.

Objects:
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              RA (2000) DE         Name
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         07 14 07     -25 44.4     NGC 2354
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File Summary:
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  FileName      Lrecl  Records   Explanations
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ReadMe             80        .   This file
table2             36      422   UBV data of D266
table3             30       71   Normal points of D266
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Byte-by-byte Description of file: table2
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   Bytes Format Units   Label   Explanations
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   1- 12  F12.4 d       HJD     Julian Day heliocentric
  16- 20  F5.3  mag     Vmag    Differential V-magnitude (D266-minus-comparison)
  24- 28  F5.3  mag     Bmag    Differential B-magnitude (D266-minus-comparison)
  32- 36  F5.3  mag     Umag    Differential U-magnitude (D266-minus-comparison)
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Byte-by-byte Description of file: table3
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   Bytes Format Units   Label   Explanations
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   1-  6  F6.4  ---     Phase   [0/1[ Phases
  10- 14  F5.3  mag     Vmag    Differential V-magnitude (D266-minus-comparison)
  18- 22  F5.3  mag     Bmag    Differential B-magnitude (D266-minus-comparison)
  26- 30  F5.3  mag     Umag    Differential U-magnitude (D266-minus-comparison)
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(End)                                         Patricia Bauer [CDS]   15-Apr-1996