2 Observation

Figure 1 shows examples of the periodic wave-like variation in the UBV LCs for selected symbiotic stars. Table 1 summarizes its basic characteristics - the amplitude, $\Delta m$, and the profile through a parameter a (Sect. 3.2). Photometric UBV observations used in this paper has been extracted from the literature and are also referred in Table 1.

Figure 1: Examples of periodic wave-like variation in the LCs of selected symbiotic binaries. Symbols, $\bullet$, $\bigtriangleup$ and +, represent observations in the U, B and V band, respectively. Profiles of the LCs are characterized by the parameter $a \sim 0.5$ (left panels), 0.5 < a < 1 (mid) and $a \approx 1$ (right), see Sect. 3.2. In cases of a poor coverage of orbital cycles, the data were folded according to their photometric ephemerides. Sources of the data are given in Table 1

 

 

Table 1: Characteristics of the LC profile: the observed amplitude, $\Delta m$, and the shape, a, (Sect. 3.2)

Object	$P_{\rm orb}$	$\beta^{\star}$	$\Delta U$ $\Delta B$ $\Delta V$	aU   aB   aV	Obs.	Note
AXPer	680	$0.02\pm0.008$	0.8  0.6  0.5	0.6  0.7  0.8	1
BFCyg	757	$0.4\pm0.12$	1.1  0.9  0.8	0.5  0.6  0.6	2	ss
CICyg	855	$0.06\pm0.011$	1.2  0.7  0.5	0.8  0.8  0.9	3	ss
EGAnd	482	$\le 0.002\pm0.001$	0.6  0.3  0.2	1.0  1.0  1.0	4	sss
AGDra	550	$0.01\pm0.008$	1.0  0.2  0.1	0.5  0.5  0.5	5
V1329Cyg	958	0.18 -0.47	1.8  1.3  1.2	0.5  0.5  0.5	6
He2-467	479	0.07 -0.2	2.2  0.6  0.3	0.6  0.6  1.0	7	s
ZAnd	759		1.5  1.0  0.7	0.5  0.5  0.6	8	ss
V443Her	594	$\sim$0.04	0.7  0.4  0.3	0.6  0.7  0.8	9
AGPeg	813	$\sim$0.03	1.1  0.6  0.5	0.5  0.5  0.5	10

$\star$ - see Appendix A for more detail.
Note: s - secondary minimum in V, ss - occasional presence of secondary minima in V, sss - secondary minima in U, B, V.
Obs.: 1 - Skopal (1998b), Skopal et al. (2000), 2 - Hric et al. (1994, 1996), Skopal et al. (1995, 1997), Skopal (1998b), 3 - Belyakina (1979, 1984, 1992), 4 - Skopal (1997), 5 - Hric et al. (1991, 1993, 1994), Kaler (1987), Kaler et al. (1987), Skopal et al. (1992, 1995), 6 - Arkhipova & Ikonnikova (1989), Chochol et al. (1999), 7 - Arkhipova & Noskova (1985, 1987, 1988), 8 - Belyakina (1986, 1992), 9 - Taranova & Yudin (1987), Belyakina (1992), Kolotilov et al. (1995), 10 - Belyakina (1965, 1970, 1992), Komárek (1990), Fernie (1985), Luthardt (1989), Tomov & Tomova (1998).