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J/A+A/454/855       Geneva photometry of W Cru               (Pavlovski+, 2006)
Indirect imaging of an aacretion disk rim in the long-period interacting
binary W Crucis.
    Pavlovski, K., Burki, G., Mimica P.
   <Astron. Astrophys. 454, 855 (2006)>
   =2006A&A...454..855P
ADC_Keywords: Binaries, eclipsing ; Photometry, Geneva

Keywords: binaries: eclipsing - accretion disk: image - techniques: photometry


Abstract:
    Light curves of the long-period Algols are known for their complex
    (asymmetry in the eclipse, light variations outside the eclipse,
    changes from cycle-to-cycle), but their interpretation is not possible
    in the standard model of binary stars. We determined that complex
    structures present in these active Algol systems could be studied with
    the eclipse-mapping method that was successfully applied to the new
    7-color photometric observations in the Geneva system of W Cru,
    belonging to the isolated group of these active Algols. Several cycles
    of this long-period (198.5-days) eclipsing binary were covered by
    observations. We used a modified Rutten's approach to the
    eclipse-mapping. The optimization of the system's parameters and the
    recovery of the disk intensity distribution are performed using a
    genetic algorithm (GA). The finding of a primary (hot) component is
    hidden in thick accretion disk confirms previous solutions. The mass
    of the primary component, M1=8.2M☉, indicates that it is a
    mid-B type star. The mass-losing component fills its critical lobe,
    which, for the system's parameters, means it is a G-type supergiant
    with a mass M2=1.6M☉. The disk is very extended geometrically,
    and its outer radius is about 80% of the primary's critical lobe. A
    reconstructed image reveals the rather clumpy and nonuniform
    brightness distribution of an accretion disk rim in this system that
    is seen almost edge-on. This clumpiness accounts for light curve
    distortions and asymmetries, as well as for secular changes.

Description:
    The 386 photometric measurements of W Cru (HD 105998) in the 7-colour
    Geneva system.
Objects:
    -------------------------------------------
       RA   (2000)   DE      Designation(s)
    -------------------------------------------
    12 11 59.2   -58 47 01   W Cru = HD 105998
    -------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        67      386   Photometric measurements of W Cru in the
                              7-colour Geneva system


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

   1- 11  F11.3 d       HJD       Heliocentric Julian date
      13  I1    ---     Q         [0/4] Photometric Q weight
                                        (Rufener 1988, Cat. II/169) (1)
  17- 21  F5.3  mag     Vmag      Magnitude in the visible
      23  I1    ---     P         [0/4] Photometric P weight
                                        (Rufener 1988, Cat. II/169) (1)
  27- 31  F5.3  mag     [U-B]     Geneva [U-B] colour index
  33- 38  F6.3  mag     [V-B]     Geneva [V-B] colour index
  40- 44  F5.3  mag     [B1-B]    Geneva [B1-B] colour index
  46- 50  F5.3  mag     [B2-B]    Geneva [B2-B] colour index
  52- 56  F5.3  mag     [V1-B]    Geneva [V1-B] colour index
  58- 62  F5.3  mag     [G-B]     Geneva [G-B] colour index
  64- 67  F4.2  ---     Fz        Airmass

Note (1): Photometric weight as follows:
      4 = observation of exceptional quality whose correlation with
          standards is remarkably well assured.
      3 = normal weight for all the good measurements conveniently
          correlated with standards.
      2 = weight conferred as soon as the least doubt exists as to the
          transparency or correlation with standards.
      1 = weight conferred as soon as no certainty of good transparency
          and good correlation with standards can be obtained (case of
          partial night for instance).
      0 = this weight sanctions all measurement for which an objective
          risk of error exists.


Acknowledgements: Gilbert Burki, Gilbert.Burki(at)obs.unige.ch

(End)    Kresimir Pavlovski [UniZagreb, Croatia], P. Vannier [CDS]   13-Jul-2006