The
parameter (Eq. 3) is defined by the luminosity ratio
and the giant radius in units of the separation of the components,
.
To determine these quantities we used published parameters and/or
made appropriate estimates. If applicable, we used spectral types
of the cool components in symbiotic binaries of
Mürset & Schmid (1999) and empirically determined dependencies
of effective temperature and linear radius upon the spectral type
given by van Belle et al. (1999). Table 4 summarizes the resulting
parameters. Their uncertainties represent mean square errors of
the mean value given by Eq. (3). A brief explanation to Table 4 is
given below for individual objects.

**AXPer**:
Skopal (1994) determined
.
The luminosity of the giant,
for the distance
pc (Skopal 2000).
The hot star luminosity,
(Mürset et al. 1991) with the uncertainty resulting from that
of *d*.

**BFCyg**:
Parameters
and
(Skopal et al. 1997). The uncertainty of the luminosity
ratio is 30%, which is relevant to its determination from
the observed fluxes.

**CICyg**:
Kenyon et al. (1991) estimated
.
Adopting their estimate of the total mass of the binary,
,
we get
*A* =
for
= 855.25 days (Aller 1954),
which yields
.
The spectral type (*ST*) of the red giant in CICyg, M5.5,
corresponds to its effective temperature,
K,
which then yields
.
Finally, Mürset et al. (1991) determined
(d/1.5kpc)^{2}.

**EGAnd**:
From the contact times of a minimum observed in continuum fluxes
at 1320Å (Pereira 1996) we determined
for the orbital period,
= 482 days (Skopal 1997)
and a circular orbit. As the minimum is caused by Rayleigh
scattering of the hot star radiation on the neutral atoms of
the cool giant wind, this is an upper limit.
The luminosity ratio for the two stars,
(Vogel et al. 1992).
The uncertainty of this ratio is assumed to be of 30%.

**AGDra**:
From the energy distribution in the spectrum during quiescence
(Greiner et al. 1997) we estimated the observed fluxes
and
ergcm^{-2}s^{-1},
i.e.
.
Smith et al. (1996) estimated the surface gravity as
(*g* in units of cms^{-2}), which for
the cool component mass of 1.5
(Mikolajewska et al. 1995),
yields
.
This value is also consistent with that corresponding to the recent
dependencies. For
and
= 550 days (Gális et al. 1999)
we have
and thus
.
We can also estimate the distance to AGDra
pc from
(
as for K3-4III giant) and
.

**V1329Cyg**:
The maximum width of the pre-outburst eclipses
(Fig. 1 of Schild & Schmid 1997),

Object | |||

AXPer | |||

BFCyg | |||

CICyg | |||

EGAnd | |||

AGDra | |||

V1329Cyg | 3.1-1.2 | <0.39 | 0.18 - 0.47 |

He2-467 | 60 | 0.05-0.03 | 0.07 - 0.2 |

ZAnd | 1 | ||

V443Her | 0.7 | 0.26 | 0.04 |

AGPeg | 1 | 0.17 | 0.03 |

Here we investigate the suggested connection between the parameters
*a* and *X* (Sect. 4.2). STB derived the parameter *X* as

(B.1) |

The meaning of individual parameters is noted in the text above. Unfortunately, there are only a few symbiotic objects for which the parameter

Figure B.1:
A correlation between the shape of the LC characterized
by the parameter a (Sect. 3.2) and the extent of the symbiotic
nebula given by the parameter X |

Object | Ref. | a |
X |
||

AGPeg | 2.0 | 7.2 | 0.50 | >15 | |

ZAnd | 2.0 | 1 | 3.5 | 0.53 | 14 |

AGDra | 2.0 | 2 | 2.6 | 0.50 | 11 |

V1329Cyg | 15 | 56 | 0.50 | 8 | |

BFCyg | 20 | 50 | 0.57 | 3 | |

CICyg | >4 | 3.7 | 0.83 | <5 | |

AXPer | 10 | 3 | 2.2 | 0.70 | 0.4 |

EGAnd | 2.0 | 4 | 0.077 | 1.0 | 0.3 |

Ref.: 1 - Fernández-Castro et al. (1988),
2 - Mikolajewska et al. (1995),
3 - Skopal et al. (in press), 4 - Vogel (1991): this value is needed to explain the nebular continuum. In contrast, the value of 3-4 yr ^{-1} suggested
by effects of the Rayleigh scattering in the far UV continuum
leads to X = 7. |

The main obstacle to determining the

In spite of these problems the present knowledge of the fundamental
parameters of symbiotic binaries makes a correlation between
*a* and *X* possible (Fig. 5).
However, further investigation is needed to determine more accurate
parameters, mainly the mass-loss rate via the wind from cool giants
in binaries, to verify the relationship between the profile of the LC
and the extent of the symbiotic nebula.

In this appendix we introduce a modification of the STB model
accounting for the additional ionizations due to the inflow of neutral
material into the ionized region through the ionization front due to
the orbital motion and the velocity of the giant wind.

At a boundary point, ,
the rate of particles,
,
crosses the area of the front,
d*S* = d
,
where d
is
a small angle around the vector ** r** pointing to
from the hot star and
is the velocity of atoms in the
direction of

(C.1) |

The velocity component, , is calculated from the velocity of a particle in the frame rotating with angular velocity ; is the position vector with respect to the centre of mass of the system. Figure 6 shows a comparison of the closed boundary calculated according to Eq. (C.1) and that of the STB model.

Abstract: What mimics the reflection binaries? Copyright ESO 2001