J/A+A/487/1129 Evolutionary models of binaries (Van Rensbergen+, 2008)
Spin-up and hot spots can drive mass out of a binary.
Van Rensbergen W., De Greve J.P., De Loore C., Mennekens N.
<Astron. Astrophys. 487, 1129 (2008)>
=2008A&A...487.1129V 2008A&A...487.1129V
ADC_Keywords: Binaries, eclipsing ; Models, evolutionary
Keywords: binaries: eclipsing - stars: evolution - stars: mass-loss -
stars: statistics
Abstract:
The observed distribution of orbital periods of Algols with a B-type
primary at birth agrees fairly well with the prediction from
conservative theory. Conservative evolution fails, however, to produce
the rather large fraction of Algols observed with a high mass-ratio.
In order to keep Algols for a longer time with a higher mass-ratio
without disturbing the distribution of orbital periods too much,
interacting binaries have to lose a significant fraction of their
total mass without losing much angular momentum before or during
Algolism. We propose a mechanism that meets both requirements.
In the case of direct impact the gainer spins up: sometimes up to
critical velocity. Equatorial material on the gainer is therefore less
bound. A similar statement applies to material located at the edge of
an accretion disc. The incoming material moreover creates a hot spot
in the area of impact. The sum of the rotational and radiative energy
of hot spot material depends on the mass- transfer-rate. The sum of
both energies overcomes the binding energy at a well defined critical
value of the mass-transfer-rate. As long as the transfer-rate is
smaller than this critical value RLOF happens conservatively. But as
soon as the critical rate is exceeded the gainer will acquire no more
than the critical value and RLOF runs into a liberal era.
Description:
This catalogue contains the data needed to follow-up the liberal
evolution of binaries with a B-type primary at birth. Loss of mass and
angular momentum is included according to the scenario as outlined in
the paper.
Tables are labeled with:
* Mass of the initial primary in solar masses
* Type of tidal interaction ("strong" or "weak") or conservative
evolution ("conser")
For example: "09strong" signifies an initial 9 solar mass primary and
strong tidal interactions (fsync=0.1), while "09weak" signifies weak
tidal interactions (fsync=1.0). "09conser" assumes conservative
evolution.
When systems evolve conservatively, the evolutionary path does not
depend on the type of tidal interaction. Therefore, in the case of 3
and 4 solar mass primaries, only the "conser" tables are given.
Binaries with a 5 solar mass primary evolve almost conservatively,
with very small differences between strong and weak tides. The table
"05strong" contains mostly conservative calculations, and only the
strong assumption if mass is lost from the system. At 6 solar mass
primaries and above, "conser" tables are always given for comparison.
Each table contains the evolutionary tracks for multiple combinations
of the initial mass ratio and orbital period. The beginning of each
evolution is characterized by a step=1. The tables start with the
lowest mass ratio and the lowest orbital period, running through
increasing periods before going to higher mass ratios.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
summary.dat 60 561 Summary of initial parameters in the models
mod/* . 21 Individual tables
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Byte-by-byte Description of file: summary.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "D-M-Y" Date Date of file addition or extension
13- 24 A12 --- FileName Name of the file, in "mod" subdirectory
27- 31 I5 --- Line Starting line number (from 0) of model
34- 37 I4 --- steps Number of steps in file with these parameters
39 A1 --- Case [wsc] (w)eak or (s)trong tidal interaction
or (c)onservative case
41- 46 F6.3 solMass Mass1 Initial mass of primary
48- 53 F6.3 d Per Orbital period of the binary
55- 60 F6.3 solMass Mass2 Initial mass of secondary
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Byte-by-byte Description of file: mod/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- step Step in model (1 for Age=0)
6- 16 E11.6 yr Age Age
18- 23 F6.3 solMass Mass1 Mass of initial primary
25- 34 E10.5 solMass/yr Mdot1 Mass loss of initial primary
36- 40 F5.3 K Teff1 Log of effective temperature of initial
primary
42- 47 F6.3 solLum Lum1 Log of luminosity of initial primary
49- 53 F5.3 --- Xc1 Hydrogen fraction (by mass) in core of
initial primary
55- 59 F5.3 --- Yc1 Helium fraction (by mass) in core of initial
primary
61- 65 F5.3 --- Xat1 Hydrogen fraction (by mass) in atmosphere of
initial primary
67- 73 F7.3 solRad Rad1 Radius of initial primary
75- 81 F7.3 d Per Orbital period
83- 88 F6.3 solMass Mass2 Mass of initial secondary
90-100 E11.5 solMass/yr Mdot2 Mass loss of initial secondary
102-106 F5.3 K Teff2 Log of effective temperature of initial
secondary
108-112 F5.3 solLum Lum2 Log of luminosity of initial secondary
114-118 F5.3 --- Xc2 Hydrogen fraction (by mass) in core of
initial secondary
120-124 F5.3 --- Yc2 Helium fraction (by mass) in core of initial
secondary
126-130 F5.3 --- Xat2 Hydrogen fraction (by mass) in atmosphere
of secondary
132-138 F7.3 solRad Rad2 Radius of initial secondary
140-146 F7.3 solRad RRoche1 Roche radius of initial primary
148-154 F7.3 solRad RRoche2 Roche radius of initial secondary
156-160 F5.3 --- beta Mass gain / Mass loss ratio (1)
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Note (1): Beta is the mass gain rate of the initial secondary (gainer)
divided by the mass loss rate of the initial primary (donor) during
RLOF (Roche Lobe Overflow). This quantity has no meaning outside RLOF
and is put equal to 1 at that time.
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Acknowledgements:
N. Mennekens, nmenneke(at)vub.ac.be
History:
* 12-Aug-2008: First version
* 20-Aug-2008: New version
* 05-Sep-2008: New files added (details in the "summary.dat" file)
* 21-Sep-2008: File "summary.dat" added
* 27-Nov-2008: New files added (details in the "summary.dat" file)
* 20-Mar-2009: New files added (details in the "summary.dat" file)
* 03-May-2010: New files added (details in the "summary.dat" file)
(End) W. Van Rensbergen [Vrije Univ. Brussel], P. Vannier [CDS] 20-Aug-2008