The present paper contains an analysis of the light curves of SV Cam observed in the period 1973-1981 (Patkós 1982), which is based on the Roche model with spotted areas on the components (Djurasevic 1992a). In Table 1 (click here) the data sequence of the individual light curves is presented. Here only the V passband light curves are considered because they are the most complete. Out of a total of 38 light curves, 18 (which are relatively well defined) are chosen to enable the estimate of the system and spotted areas parameters. There are indications that they all belong to one activity cycle (Busso et al. 1985).
In the analysis of the light curves, we avoided the somewhat
questionable practice of forming normal points, and included all observations.
We obtained the optimal model parameters trough the minimization of
, where 
is the residual between observed (LCO) and
synthetic (LCC) light curves for a given orbital phase. The minimization of S
is done in an iterative cycle of corrections of the model parameters, based on
the Marquardt's algorithm. This inverse problem method is characterised by fast
and reliable convergence, that allows one to efficiently estimate the system
parameters. The method also gives standard errors.
Since the results of the light curve analysis are very dependent on the choice of the adopted working hypothesis, the analysis is carried out within the framework of several hypotheses (single and double spotted areas; spots on the primary and spots on the secondary).
The present light curve analysis yields the filling coefficients of the critical Roche lobes F1 and F2, about 0.88 and 0.64 for the primary and secondary, respectively (see Tables 2 (click here) and 3 (click here)). Since the critical Roche lobes are filled by the components to a high degree, tidal effects are expected to contribute to synchronisation of the rotational and orbital periods. Therefore, in solving the inverse problem, for nonsynchronous rotation coefficients we adopted the values f1,2=1.0.
For such a case where neither the primary nor the secondary fill the critical
Roche lobes, determination of the mass ratio of the components by analysing
light curves only is not reliable. For this reason the mass ratio is fixed by
assuming the value q=m2/m1=0.71, estimated spectroscopically
(Budding &
Zeilik 1987). On the basis of its spectral type (G3V) the temperature of the
primary is also fixed 
.
In the programme for solving the inverse problem, the linear limb-darkening
coefficients are determined on the basis of the stellar effective temperature
and of the stellar-surface gravity, according to the given spectral type, by
using the polynomial proposed by
Dıaz-Cordovés et al. (1995). For the
gravity-darkening coefficients of the stars the value of 
was adopted. Lucy (1967) and Osaki (1970) regard this value as being
justifiable for stars with convective envelopes.
The temperature of the secondary (about 4300 K) was significantly lower
than that of the primary. Therefore, its contribution to the total brightness
of the system is relatively small. Hence one can expect that the spotted areas
on the secondary yield comparatively small photometric effects. In this case,
the model for the light curve fitting requires very large spotted regions with
a high temperature contrast with respect to the surrounding photosphere. The
spotted areas are too large even for a temperature contrast 
,
which yields the spot temperature of about 2600 K. In the case of some light
curves analysed here the fitting of observations with a synthetic light curve
is not satisfactory. The basic parameters of the system, such as the size of
the components, the orbit inclination and the temperature of the secondary
obtained by analysing the individual light curves, should be variable within
significant limits, which is unacceptable. Therefore, this hypothesis is
rejected as unrealistic.
Under the assumption of spotted areas being on the primary, the optimum
synthetic light curves fit much better the observations. The light curves
were then analysed in the framework of the single and double spot models.
For the temperature contrast between the spotted area and the surrounding
photosphere it is assumed 
, yielding the spot temperature
to be about 3770 K. Cellino et al. (1985) inferred from the infrared
observations a spot temperature of 3780 K. On the basis of this result the
assumed value for the spotted area temperature contrast may be considered as
justified.
In analysing the light curves the following procedure is applied. First, on the basis of the light curve form, the curve No. 10 (see Tables 1 (click here) -3 (click here) and Fig. 3 (click here)) was chosen as the cleanest from spot effects. In analysing it, the optimisation begins using only the basic model parameters. After achieving a first convergence, one also includes free parameters related to spots in the iterative optimisation process.
The basic parameters of the system, obtained in this way, are used as starting
points in the inverse-problem solution for other light curves. Their
analysis begun by optimisation in the spot parameters. When the optimisation
based on these parameters does not secure a further minimization of
, the basic system parameters have to be introduced in the
iterative process. Namely, one cannot in advance exclude the possibility of
certain changes of some of these parameters during the analysed period of time.
Using this procedure we optimize all free-parameters of the model in the final
iterations. In this way we save some computer time because a smaller number of
iterations is needed.
Table 1: Data sources for the analysis of the observed
light curves (Patkós 1982)
for the active CB SV Cam (V-filter)
Note: JD - Julian Dates of the observations, N - total number of
observations for the given light curve.
Table 2: Results of the analysis of the SV Cam light curves obtained
by solving the inverse problem
for the Roche model with one spotted area on the primary component
Fixed parameters:
q=m2/m1=0.71 - mass ratio of the components,
- temperature of the primary,
- spotted area temperature coefficient,
f1=f2=1.00 - nonsynchronous rotation coefficients of the components,
- gravity-darkening coefficients of the components,
u1=0.66 - limb-darkening coefficient of the primary.
Note: No. - data set No., 
- spotted area angular dimensions, 
- spot
longitude and 
- spot latitude (all in degrees), F1, F2 - filling
coeficients for critical Roche lobes of the primary and secondary,
T2 - temperature of the secondary, i - orbit inclination (in degrees),
u2 - limb-darkening coefficient of the secondary, 
-
dimensionless surface potentials of the primary and secondary, R1, R2 -
stellar polar radii in units of the distance between the component
centres and - final sum of squares of residuals between
observed (LCO) and synthetic (LCC) light curves.
Table 3: Results of the analysis of the SV Cam light curves obtained
by solving the inverse problem
for the Roche model with two spotted areas on the primary component
Fixed parameters:
q=m2/m1=0.71 - mass ratio of the components,
- temperature of the primary,
- spotted areas temperature coefficient,
f1=f2=1.00 - nonsynchronous rotation coefficients of the components,
- gravity-darkening coefficients of the components,
u1=0.66 - limb-darkening coefficient of the primary.
Note: No. - data set No., 
- spotted areas angular dimensions,
- spots longitude and 
- spots latitude (all in
degrees); F1, F2 - filling coeficients for critical Roche lobes of the
primary and secondary, T2 - temperature of the secondary, i - orbit
inclination (in degrees), u2 - limb-darkening coefficient of the secondary,
- dimensionless surface potentials of the primary and
secondary, R1, R2 - stellar polar radii in units of the
distance between the component centres and 
- final sum of
squares of residuals between observed (LCO) and synthetic (LCC) light curves.