Access to Astronomical Catalogues

J/MNRAS/373/1483  W UMa type and CAB stars dynamical evolution    (Eker+, 2006)
Dynamical evolution of active detached binaries on the logJo-logM diagram and
contact binary formation.
    Eker Z., Demircan O., Bilir S., Karatas Y.
   <Mon. Not. R. Astron. Soc., 373, 1483-1494 (2006)>
   =2006MNRAS.373.1483E
ADC_Keywords: Binaries, spectroscopic ; Binaries, orbits ; Stars, masses

Keywords: binaries: spectroscopic - stars: evolution - stars: mass-loss


Abstract:
    Orbital angular momentum (OAM, Jo), systemic mass (M) and orbital
    period (P) distributions of chromospherically active binaries (CAB)
    and W Ursae Majoris (W UMa) systems were investigated. The diagrams of
    and logJo-logP, logM-logP and logJo-logM were formed from 119 CAB and
    102 W UMa stars. The log Jo-logM diagram is found to be most
    meaningful in demonstrating dynamical evolution of binary star orbits.
    A slightly curved borderline (contact border) separating the detached
    and the contact systems was discovered on the logJo-logM diagram.
    Since the orbital size (a) and period (P) of binaries are determined
    by their current Jo, M and mass ratio, q, the rates of OAM loss
    (dlogJo/dt) and mass loss (dlogM/dt) are primary parameters to
    determine the direction and the speed of the dynamical evolution. A
    detached system becomes a contact system if its own dynamical
    evolution enables it to pass the contact border on the logJo-logM
    diagram. The evolution of q for a mass-losing detached system is
    unknown unless the mass-loss rate for each component is known.
    Assuming q is constant in the first approximation and using the mean
    decreasing rates of Jo and M from the kinematical ages of CAB stars,
    it has been predicted that 11, 23 and 39 per cent of current CAB stars
    would transform to W UMa systems if their nuclear evolution permits
    them to live 2, 4 and 6Gyr, respectively.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        86      119  *Physical parameters of the chromospherically
                              active binaries (CAB)
table2.dat        86      102   Physical parameters of the W UMa stars

Note on table1.dat: CAB stars from Karata et al. (2004, Cat. J/MNRAS/349/1069)



See also:
   V/76 : Chromospherically Active Binaries (Strassmeier+ 1993)
   J/MNRAS/349/1069 : Chromospherically active binaries (Karatas+, 2004)


Byte-by-byte Description of file: table[12].dat

   Bytes Format Units    Label     Explanations

   1-  3  I3    ---      Seq       Sequential number
       4  A1    ---      n_Seq     [*] Possible member of young group (1)
   6- 16  A11   ---      Name      Name
  18- 35  A18   ---      SpType    MK spectral type
  37- 38  A2    ---      Evol      Stage of evolution (G, MS, SG) in table1
                                    or type (W, A) in table2 (2)
  40- 44  F5.3  solMass  Mtot      Total mass (M1+M2)
  46- 50  F5.3  ---      q         Mass ratio (M2/M1)
  52- 59  F8.4  d        Per       Orbital period
  61- 66  F6.3  solRad   R1        ? Radius of the primary
  68- 73  F6.3  solRad   R2        ? Radius of the secondary
  75- 80  F6.3 [g.cm2/s] logJo     Orbital angular momentum (OAM) (cgs)
  82- 86  F5.3  ---      Jspin/Jo  ? Total spin angular momentum as fraction
                                     of orbital angular momentum

Note (1): Stars flagged with * are possible members of young moving groups
     (<0.6Gyr) and the other are older (3.86Gyr for table1, 5.47Gyr for
     table2) field systems.
Note (2): Stages as follows:
      G = system with at least one component being a giant
     SG = system with at least one subgiant but no giant
     MS = system with unknown secondaries were classified according to primaries
      A = A-type system, in which the more massive component (the greater)
          is the hotter star.
      W = W-type system as W UMa itself, in which the hotter component (the
          star eclipsed at the primary minimum) is smaller and less massive


History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    14-Aug-2007