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J/AJ/134/179        Ligth minimum times of TY Boo                  (Yang+, 2007)
Orbital period changes for the weak-contact binary TY Bootis.
    Yang Y.-G., Dai J.-M., Yin X.-G., Xiang F.-Y.
   <Astron. J., 134, 179-184 (2007)>
   =2007AJ....134..179Y
ADC_Keywords: Binaries, eclipsing ; Photometry

Keywords: binaries: close - binaries: eclipsing - stars: evolution -
          stars: individual (TY Bootis)

Abstract:
    We present a detailed period analysis of TY Bootis, based on all
    available light minimum times covering about 80 years. We discovered
    that there exists a cyclic variation overlaying a secular period
    decrease from the distorted (O-C) diagram. A long-term decrease with
    a sinusoidal oscillation (i.e., eq. (2)) or with a light-time effect
    (i.e., eq. (3)) may be reasonable due to the smaller difference
    between their sum of residuals. The sinusoidal change with a period of
    59.7 yr for equation (2) can be attributed to either a light-time
    effect or cyclic magnetic activity of both components. For the assumed
    third body, the period and eccentricity of the light-time orbit are
    P3=58.6yr and e'=0.1744, respectively. If the existence of an
    additional unseen body is true, this binary may be a tertiary system.
    The long-term orbital period decrease suggests that TY Boo is
    undergoing a mass transfer from the primary component to the secondary
    component at a rate of dm/dt=-3.15x10-8M☉/yr for equation (2)
    or dm/dt=-2.90x10-8M☉/yr for equation (3). As its mass
    transfers, accompanied by angular momentum loss due to mass outflow
    L2, this binary will evolve into a deep contact configuration.

Description:
    CCD observations in the R band for TY Boo were performed using the 1 m
    telescope at Yunnan Observatory in China on 2006 June 3.
Objects:
    ---------------------------------------------
       RA   (2000)   DE      Designation(s)
    ---------------------------------------------
    15 00 46.9   +35 07 55   TY Boo = V* TY Boo
    ---------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        55      292   All available light minimum times for TY Bootis
refs.dat          72       84   References


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

   Bytes Format Units   Label     Explanations

   1- 12  F12.4 d       HJD       Heliocentric Julian Date of minimum
  14- 21  F8.1  ---     Epoch     Epoch E (in periods)
  23- 25  A3    ---     Method    Method used (1)
  27- 28  A2    ---     Min       [I II] Primary (I) or secondary (II) minimum
  30- 36  F7.4  ---     (O-C)     (O-C) residual with Kreiner ephemeris 2001:
                                        2447612.6035+0.31714910E (Eq.1)
  38- 44  F7.4  ---     (O-C)1    (O-C)1 residual with parabolic curve (Eq.2)
  46- 52  F7.4  ---     (O-C)2    (O-C)2 residual with 3rd body (Eq.3)
  54- 55  I2    ---     Ref       Reference, in refs.dat file

Note (1): Method used as follows:
     pg = photographic measurement
     vi = visual observation
     pe = photoelectric data
    CCD = charge-coupled device


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

   Bytes Format Units   Label     Explanations

   1-  2  I2    ---     Code      Reference code
   4- 72  A69   ---     Ref       Reference


History:
    From electronic version of the journal
(End)                  Greg Schwarz [AAS], Patricia Vannier [CDS]    22-Aug-2009