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 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:
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FileName Lrecl Records Explanations
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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
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Note on table1.dat: CAB stars from Karata et al. (2004, Cat. J/MNRAS/349/1069)
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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
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Bytes Format Units Label Explanations
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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
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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
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Aug-2007