3. Discussion on the individual variables

3.1. The variables in the SMC

HIP 5267 = HD 6884 = R40, B9IaeThis object is an LBV, discovered by Szeifert et al. (1983), and started a prominent SD (S Dor) phase around 1960, with a steep rise in 1988. The light curve has been described by van Genderen et al. (1997b, Paper I). In a forthcoming paper it will be demonstrated that it is a multi-periodic variable (Sterken et al. 1998). Hipparcos observed the star during the steep rise (Fig. 1 (click here)a) partly coinciding with the data groups 5-6-7 and 8-9-10 in Paper I and the gaps in between. After subtraction of the long-term rise, the period search applied to the Hp data revealed as best period for the micro variations 84.8d, 86.2d and 96.2d. The last one lies well between the periods for the two groups mentioned above, viz. 93.5d and 98.3d and supports the increasing trend of the period for this type of micro variations noticed during the rise to maximum brightness of other LBVs (in Paper I they are called the 100 d-type micro variations). The other two periods should then be spurious.

HIP 5397 = HD 7099 = R42, B3IaBased on still unpublished VBLUW photometry made between 1987 and 1990, this star is known to be variable with a total range of 015 and a time scale of
2-4 weeks. The Hp data show a light range of 011 (Fig. 1 (click here)b).

The periodogram of the Hp data shows, with little difference in significance, peaks near 15 d, 23 d and 47 d. The periodogram for the unpublished V data, which are much more numerous, show as most significant peaks near 16 d, 16.6 d, 20.6 d and 25.3 d. Evidently, the significance of the Hp periods 15 d and 23 d are supported by these ones, while the one at 47 d may be the 3P or 2P alias, respectively, of the other two.

HIP 5714 = HD 7583 = R45, A0Ia⁺ Based on still unpublished VBLUW photometry made between 1986 and 1989 this hypergiant is known to be variable with a total range of 012 and a time scale of 6-11 weeks. The Hp data show a similar light range (Fig. 1 (click here)c).

The periodogram of the Hp data shows a most pronounced peak near 24.8d and with less significance peaks near 67d and 49d. The periodogram for the much more numerous unpublished V data shows a number of best periods between 50d and 77d supporting the last two periods for the Hp data. The 24.8d Hp period probably results from the window function since it is completely absent in the V data.

3.2. The variables in the LMC

HIP 23177 = HDE 270920, G2Ia The variability, discovered by Grieve et al. (1985), showed in the past a total range of 03 in at a time scale of 250d. The light curve of the Hp data in Fig. 1 (click here)d shows about 5 cycles with time scales of
and ranges between 01 and 04. Thus, the overall behaviour did not change.

HIP 23527 = HDE 269018, B2.5IaThe variability has been established by the Hp data, showing a range of 010 (Fig. 1 (click here)e). The periodogram shows four candidate periods which in order of decreasing significance are: 14.6d, 6.3d, 32.5d and 30.2d. The phase diagram for the best one is shown in Fig. 4 (click here). The third may be the spectral window function and the fourth the 2P alias of the first period.

HIP 23718 = HD 33579 = R76, A3Ia⁺The variability of one of the most luminous stars in the LMC has been established by van Genderen (1979). It was characterized by a 100d oscillation with a range of 005. Later, it appeared that an underlying and stronger oscillation exists with a presumable time scale of 1 - 3 yr and a range of 01 (Grieve & Madore 1986).

  
Figure 4: The phase diagram for HIP 23527 = HDE 269018

  
Figure 5: The phase diagram for the long-time oscilation (top) and the weak short-time scale oscillation of HIP 23718 =
HD 33579 = R 76. Residuals from the upper curve were used to construct the lower curve

The Hp data show for the first time both oscillations, the weak and the strong one, very well. Figure 1 (click here)f shows at least two long-time scale cycles of the strong oscillation with a time scale of 2yr and a range of 012. Figure 5 (click here) (top panel) shows the phase diagram for a 620 d period. The periodogram for the weak oscillation with a total range of 003, derived from the scatter around the mean light curve, reveals a number of peaks which in order of decreasing significance are: 105d, 81d, 57d and 70d. Since the first one is similar to the quasi-period found earlier which was based on almost 5yr of monitoring, we presume that this is the true period. Figure 5 (click here) (bottom panel) shows the phase diagram. However, it must be emphasized that the way of drawing the mean curve through the strong oscillation is not completely objective, though we do not expect much influence on the periodogram.

The importance of the Hp light curve lies in the fact that both oscillations can be seen simultaneously, the weak one superimposed on the strong one. This is a support for the study of the atmospheric dynamics with the aid of spectra by Nieuwenhuijzen et al. (1997), who have identified both types of oscillations in a spectroscopic data set obtained in 1986 and 1987.

HIP 24080 = HDE 269128 = R81, B2.5IabBased on Strömgren photometry, made by the LTPV group, Stahl et al. (1987) discovered that this LBV is also an eclipsing binary with a period of 74.59d.  Cyg-type variations are superimposed on the light curve. The depth of the primary minimum amounts to 04. No secondary minimum is present. For the  Cyg-type variations a quasi-period was established amounting to 24d (van Genderen et al. 1992).

By collecting the eclipses seen in the Hp data (Fig. 1 (click here)g) and in the LTPV data (Manfroid et al. 1994, Sterken et al. 1993, 1995), it became clear that the linear ephemeris by Stahl et al. (1987) needed a small revision. A new linear ephemeris was determined by selecting all observations close to mid eclipse, i.e. with Hp and . In this way we extracted from the LTPV catalogues and the Hp data 30 and 3 observations, respectively. In total the time base amounts to 44 cycles. The least-squares solution resulted in the following relation:

The plot of the values is shown in Fig. 6 (click here). No search for a period for the  Cyg variations at maximum light was undertaken. The reason is that the number of observations is too low. Besides, the light curve is complicated. Instead of a secondary minimum, the light curve only shows a steady decline between successive primary minima (see Stahl et al. 1987).

HIP 24347 = HDE 269216, B8IThis object has spectroscopically a strong resemblance with LBVs near minimum light such as HDE 269006 = R71 (Prinja & Schild 1991). Indeed, the Hp light curve in Fig. 1 (click here)h strongly supports their suspicion as will be explained below. The light curve shows two long-time scale cycles amounting to 700d and 500d and a range of 04 with superimposed  Cyg-type variations with a range of 01 and a time scale of the order of weeks (see below). This estimated time scale is based on the analysis of the scatter around the mean curve sketched through the two cycles and is therefore not completely objective. The periodogram revealed a few peaks near the following periods in order of decreasing significance: 16.1d, 20.5d, 8.1d and 9.9d. The latter two may be the 1/2P aliases of the first two periods. Figure 7 (click here) shows the phase diagram for 16.1d.

  
Figure 6: The versus cycle number E of HIP 24080 = HDE 269128 = R81 based on the binary period amounting to 74.55d

  
Figure 7: The phase diagram with P=16.1 d for the short-time scale oscillation of HIP 24347 = HDE 269216. Residuals read from a smooth curve through the long-time scale oscillation in units of 001

The resemblance of the light variation with that of R71 is striking. The latter showed between 1970 and 1980 an enhanced apparent brightness of . Subsequently, two, but much weaker active states occurred lasting 5 and 3 yr and with ranges of a few 01. The latter are roughly similar to the two cycles of our program star. According to the new nomenclature introduced by van Genderen et al. (1997a), these episodes of enhanced brightness are called "normal S Dor (SD) phases''.

Superimposed on these episodes, R71 also shows  Cyg -type variations in the order of 2-4 weeks (e.g. van Genderen et al. 1997b). All these characteristics in common support the suspicion that HDE 269216 is indeed an LBV.

HIP 24988 = HDE 271182 = R92, F8Ia⁺ The variability found by Eggen (1983), has been confirmed by Grieve et al. (1985), van Genderen et al. (1986) and van Genderen & Hadiyanto (1989). The light curve showed oscillations amounting to 200d to 250d, with a range of a few 01. The Hp light curve behaves similarly (Fig. 2 (click here)a). There are almost five cycles with a time scale of 260d. The extrema of the brightness hover between Hp = 9.7 and 10, which is fainter by than the magnitudes from the references quoted above: = 9.6 - 9.7. This difference is larger than any of the value listed in Tables 1-3. For the minima of the oscillations the difference is even 03. Therefore, it might be that still another, much longer oscillation is present.

HIP 25448 = HDE 269541, A8:Ia⁺ The variability, with unknown time scale, was first detected by Grieve & Madore (1986). The magnitude limits for were 10.40 and 10.57. The Hp light curve (Fig. 2 (click here)b) confirms the variability, but with a lower range of 01. The periodogram shows a few peaks which in order of decreasing significance are: 8.1d, 24.6d, 12.0d, 40.5d and 27.0d. The last one is presumably the result of the spectral window function. The first period, although the most significant one, is not compatible (as well as the other ones) with the empirical evidence that such late type star should have much longer quasi-periods say  100d (e.g. Burki 1976; Sterken 1977). The periodogram between 100d and 400d reveals peaks (but with a significance comparable to those mentioned above, but much less than for 8.1d) near 182d and 146d. We cannot claim any conclusion based on these results.

  
Figure 8: The phase diagram for HIP 25815 = HDE 269660 = R112

HIP 25615 = HDE 269594, F8IaThe variability was suspected by van Genderen et al. (1982) and Grieve & Madore (1986). The last mentioned authors also detected the largest range: 019 and a possible time scale of  1 yr. The Hp light curve shows for the first time how the variability looks like: four consecutive oscillations with a time scale of  200d and a range even up to 026 (Fig. 2 (click here)c).

HIP 25815 = HDE 269660 = R112, B2IaThe Hp light curve demonstrates for the first time that the star is variable with a range of 01 (Fig. 2 (click here)d). The periodogram shows a few peaks with little difference in significance: 3.656d, 10.79d and 5.390d. Arbitrarily we have chosen the second period for the phase diagram in Fig. 8 (click here). If this is the real period, then the first and third period are the 1/3P and 1/2P aliases of 10.81d.

HIP 25892 = HDE 269697, F5IaAlthough included in a number of photometric programs performed between 1970 and 1990 (e.g. Grieve & Madore 1986), no significant light variations were noticed. The Hp light curve clearly demonstrates for the first time that the star is variable with a range of 01 (see Fig. 2 (click here)e). The long-time scale sloping trend of the brightness downward, may be an artifact of statistical effects. It is not caused by the use of a wrong colour in the Hipparcos reductions: the colour used was within 0.01 mag from the correct value.

The periodogram for , showing a lot of noise below 100d, revealed two nearly equally significant peaks for 48.0d and 84d. The mean curve in the phase diagrams for both ones have an amplitude of 005 and a scatter of the same amount. No decision can be made which of these two is best.

HIP 26135 = HDE 269781 = R118, B9IaThis star was suspected variable by Rosendhal & Snowden (1971) and van Genderen et al. (1982). Only the Hp data demonstrate the variability unambiguously with a range of 014 (Fig. 2 (click here)f). The periodogram revealed as the most significant peak a period near 39.0d, of which the phase diagram looks very acceptable. A few less significant peaks appeared between 20d and 32.0d (21.8d, 24.4d, 27.2d 31.2d, possibly a few of them are related to the window function) and near 93.0d and 61.0d.

HIP 27868 = HDE 270305, B3/5IaThe Hp light curve demonstrates for the first time its variability (Fig. 2 (click here)g). The brightness shows a gradual decline amounting to 01 during the three years of observing. Due to the faintness of the object it is impossible to say whether also a real short-term variation is present. The mean Hp magnitude amounts to 11.79 and the only magnitude known so far amounts to = 11.73 by Ardeberg et al. (1972). Thus, the difference is small.

3.3. The variables in the Galaxy

HIP 37444 = HD 62150, B4IaThe variability is known and based on VBLUW photometry. Considering the time scale of long strings of observations, the period could not be smaller than say 20d. A possible quasi-period of 45.0d was suggested by van Genderen et al. (1985) and van Genderen (1985). Figure 2 (click here)h shows the light curve for the Hipparcos observations.

The periodogram of the Hp data revealed only a small peak near 43.0d, while near 36.4d a much stronger peak is present. Further, there are a few peaks close around 73d, which we consider as the 2P aliases of 36.4d. Figure 9 (click here) shows the phase diagram for 36.4d.

  
Figure 9: The phase diagram for HIP 37444 = HD 62150

HIP 42570 = HD74180, F2Ia⁺The variability was discussed by Steemers & van Genderen (1986), but the number of observations was too low to find a reliable quasi-period. It could be somewhere close to 3 months. Also the range of 015 was not reliable. Unpublished data made by the LTPV group between JD2448646 and JD2449400, comprising 23 data points, contain a few strings of observations excluding cycle lengths shorter than say 40d.

The Hp light curve (Fig. 3 (click here)a) shows a range of 006. The periodogram for P longer than 40d revealed peaks near 53d, 80d and 160d. The latter may be the 3P and 2P alias of the first two periods, respectively.

HIP 45467 = HD 80077, B2/3Ia⁺The variability has been discussed by van Genderen et al. (1992), who suggested as possible quasi-periods 41.5d or 55.5d. Long strings of observations exclude periods much shorter than these ones. According to Carpay et al. (1989, 1991) the star could be an LBV. The relative large light range, viz. 02, supports that suggestion as well as the possible presence of a shell (Houk 1978).

The Hp data, shown in Fig. 3 (click here)a, partly overlap with the observations made by van Genderen et al. (1992) in the Walraven VBLUW system, which also show a light range of 02. In order to make a combined data set, the Hp magnitudes were transformed to V. At three occasions observations in both photometric systems were made nearly simultaneously (within 2d). It appeared that the difference = = 007 (see Table 1 (click here); is the V of the UBV system transformed from the V of the Walraven system). The periodogram of the combined data set revealed as most significant peaks those near 66.5d and 55.5d and with much less significance peaks near 76.0d and 41.4d. The second and fourth period were the most significant ones for the V data alone. The inclusion of the Hp data has shifted the highest significance to 66.5d. However, its phase diagram as well as that for 55.5d period, show close to the phase for maximum light two low-brightness data points (one V and one Hp point) representing the extreme deep minimum near JD 2447915 (see the light curve in van Genderen et al. 1992, Fig. 2). Therefore, we cannot arrive at a conclusion concerning these two periods.

   

Star Sp n Notes

HIP 05267 = R40 B9Iae-FIae 0.02 7

HIP 05397 = R42 B2.5/3Ia -0.05 2 1

HIP 24080 = R81 B2.5Iab -0.04 1

HIP 42570 = HD 74180 F2Ia 0.13 1 1

HIP 45467 = HD 80077 B2/3Ia⁺ 0.07 3 2

HIP 54463 = V382Car G0Ia⁺ 0.18 4 3

HIP 67261 = V766Cen G8-K3Ia⁺ -0.15 4

HIP 89956 = V4029Sgr B9Ia⁺ 0.04 4 2

HIP 89963 = V4030Sgr B5/8Ia⁺ 0.08 4 2

Notes to Table 1 (click here):
¹ Unpublished Walraven VBLUW and /or Strömgren uvby
photometry.
² van Genderen et al. (1992).
³ Achmad et al. (1992).
⁴ Comparison based on overlapping parts of the light curve
(van Genderen 1992).

HIP 53444 = HD 94878 = GG Car, BeThis peculiar variable is probable a complicated binary with an eccentric orbit and of which one of the components is an intrinsic variable (Gosset et al. 1984, 1985). These authors write that no precise period can actually be derived from the radial velocity data. They take tentatively the single value as the best, viz. 31.020d, but if it is a binary indeed, the real one should be 62.039d.

The light curve for the Hp data is shown in Fig. 3 (click here)c. The periodogram of the Hp data confirm that the shortest of the two periods mentioned above has slightly more significance than its double. Yet the phase diagram for the former shows larger scatter at constant phase, sometimes up to 02, than for the latter. Figure 10 (click here) shows the phase diagram for the long period. The reason for the larger scatter mentioned above is that the two extrema of the double waved light curve are different in height, supporting the long period. This phenomenon has also been noticed by Gosset et al. (1984). The remaining part of the scatter, which is still  01, must be caused by the variability of at least one of the components.

  
Figure 10: The phase diagram for HIP 53444 = HD 94878 = GG Car

HIP 54463 = HD 96918 = V382 Car, G0Ia⁺Although this hypergiant was suspected to be variable on a long time scale with a range of  005 (van Genderen et al. 1986; Achmad et al. 1992), the Hp data show for the first time how the light curve looks like (Fig. 3 (click here)d): almost three cycles of varying shape and range. The largest range observed amounts to 012. The time scale amounts to and the best phase diagram is obtained with 556d. No short-time scale variations are evident. Therefore, it is not surprising that a string of observations made in a short time interval suggested constancy (Berdnikov & Turner 1995).

HIP 67261 = HR 5171A = HD 119796 = V766 Cen, G8-K3 Ia⁺The photometric history has been discussed by van Genderen 1992 (Paper II). The star shows in the interval 1973-1991 a stable period of 494d. The Hp light curve (Fig. 3 (click here)e) shows almost three cycles of varying shape and range. The largest range observed amounts to 03. The rising branch of the first cycle is in common with the cycle belonging to maximum 17 (JD2448320, E = 8) of the light curve in Paper II.

The Hp data was affected by the use of a wrong colour index in the data reductions, in fact, the main catalogue gives as spectral type AV. As a result, there is a slope in the Hp data as well as a systematic offset with the ground-based data. At the time of submitting this paper, the official correction equations had not been released yet.

Between the two high amplitude cycles, there is a low one at JD2448670, which we considered as maximum 18 with E = 9. The long-time scale light curve discussed in Paper II also shows in visual light such low amplitude cycles (e.g. maximum 15), which appeared to be much more pronounced in the ultraviolet and therefore considered real.

The next high amplitude cycle is maximum 19 ( E =10), of which the precise epoch could not be determined due to the lack of observations. It should lie between JD2448890 and JD2449220. The least-squares solution based on the epochs listed in Table 3 (click here) of Paper II and the two new ones, thus, between E=-6 and 9 (omitting E=-8, -7, see below, and E=10) resulted in practically the same linear ephemeris as in Paper I:

Mean errors are given. Thus, the new maxima support the stability of the period during this time interval. Figure 11 (click here) shows the values versus the cycle number E. The value for cycle number E=10 lies between -13d and -343d.

  
Figure 11: The in fractions of a cycle versus cycle number E of HIP 67261 = HR 5171A = HD 119796 = V766 Cen

The early maxima at E=-8 and -9 indicated that the period was much shorter at that time. (It should be noted that the values for these two maxima are listed in Table 3 (click here) of Paper II as negative values instead of positive as they should).

HIP 80782 = HD 148379 = QU Nor, B2IabThe variability has been found by Feinstein (1968) and a number of other investigators listed by van Genderen (1986, Paper III). The quasi-periodicity derived in the latter paper possibly amounts to 13.35d.

   

Star Sp mean mag range Remarks

HIP HD R gal.frgr. adopt. Hp (m)

5267 6884 40 B9Iae-FIae 0.09 0.14^{a b} 4.00-3.94 -9.5-9.7 LBV

5397 7099 42 B2.5/3Ia 0.08 0.12^c 10.96 11.00 -0.04^b 0.19 4.20 -9.8

5714 7583 45 A0Ia⁺ 0.07 0.15^c 10.21 10.17 0.04 0.12 3.96 -9.7

23177 270920 G2Ia 0.08 0.24^d 10.13 9.99 0.14 0.40 3.725 -9.5

23527^e 269018 B2.5/3Ia 0.16 0.16 11.70 11.66 0.04 0.10 4.22 -8.7

23718 33579 76 A3Ia⁺ 0.12 9.22 9.15 0.07 0.10 3.90^f -9.75^f

24080 269128 81 B2.5Iab 0.13 0.15^g 10.40^h 10.47^h -0.07^b 0.20ⁱ 4.30 -10.4 LBV

24347^e 269216 B8I 0.12 0.12^j 10.70 10.78 0.10^k 4.09 -9.0 LBV^e

24988 271182 92 F8Ia⁺ 0.10 0.10^l 9.80 9.7 0.30 3.72 -9.4

25448 269541 A8Ia⁺ 0.06 0.07^m 10.55 10.46 0.09 0.17 3.86 -8.4

25615 269594 F8Ia 0.12 0.12 10.71 10.55 0.16 0.26 3.78 -8.5

25815^e 269660 112 B1.5/2Ia 0.14 0.14 11.13 11.17 0.11 4.25 -9.3

25892^e 269697 F5Ia 0.12 0.12 10.43 10.35 0.10 3.82 -8.6

26135 269781 118 B9Ia 0.11 0.15ⁿ 9.90 9.90 0 0.14 4.01 -9.7

27868^e 270305 B3/5Ia 0.10 0.10 11.79 11.73 0.10 4.16 -8.2

notes to Table 2 (click here):

^a Szeifert et al. (1993). ^b See comparison in Table 1 (click here). ^d Mantagazza (1992).

^e Variability discovered by Hipparcos. ^f Nieuwenhuijzen et al. (1997).

^g Wolf et al. (1981). ^h Outside eclipse value.

ⁱ Eclipse depth 04. ^j Prinja & Schild (1991) used 008.

^k Range normal SD phases 035. ^l van Genderen & Hadiyanto (1989) used 009.

^m Grieve & Madore (1986). ⁿ van Genderen et al. (1983).

   

Star Sp Hp max range Remarks

HIP HD Name

37444 62150 B4I 7.79 7.68 0.11 0.12 4.17^a -8.0^a

42570 74180 F2Ia 3.93 3.84 0.09^b 0.06^c 3.85^d -8.8^d

45467 80077 B2/3Ia⁺ 7.57 7.58 -0.01^b 0.20 4.28^e -11.1^e LBV?^e

53444 94878^g GG Car^g Be 8.80 8.72 0.08 0.2^f

54463ⁱ 96918 V382 Car G0Ia⁺ 4.09 3.95 0.11^b 0.12 3.72^h -9.0^h

67261 119796 V766 Cen G8Iae⁺-K3Ia⁺ 6.70 6.8 ^b 1 3.59^j -10.8^j HR5171A

80782 148379 QU Nor B2Iab 5.44 5.36 0.08 0.11 4.26^k -9.0^k

89956 168607 V4029 Sgr B9Ia⁺ 8.23 8.16 0.07^b 0.31 3.97^l -8.7^l LBV

89963 168625 V4030 Sgr B5/8Ia⁺ 8.48 8.39 0.09^b 0.19 4.08^l -8.6^l LBV?^m

Remarks to Table 3 (click here):

^a Averages from Table 1 (click here) in van Genderen (1985). ^b See comparison in Table 1 (click here).

^c Not reliable (Steemers & van Genderen 1986). ^d Steemers & van Genderen (1986).

^e Steemers & van Genderen (1986), also Carpay et al. (1991). ^f Eclipse depth 04.

^g See Gosset et al. (1984, 1985). ^h Achmad et al. 1992.

ⁱ Characteristics of variability discovered by Hipparcos. ^j van Genderen (1992).

^k van Genderen (1986). ^l van Genderen et al. (1992). ^m Nota et al. (1996).

There are only a small number of days with Hp data (Fig. 3 (click here)f), but during five consecutive days the star has been monitored with a time resolution of   1h comprising 69 observations. The phase diagram for all these data do not contradict the suggested quasi-period above, but to state that it is a confirmation would be exaggerated. Anyway, long strings of observations discussed in Paper III seem to exclude periods shorter than say 10d. A period search with the present Hp material has no sense due to the low number of stretches of observations.

The long series of 69 observations are plotted in Fig. 12 (click here) as a function of BJD, showing a smooth trend with a scatter amounting to 005. The trend confirms the photometry of Paper III that data sets a few hours apart can show significant variations of the order of a few percent. These data would cover a phase interval of 0.27 if the period of 13.57 d is real.

  
Figure 12: The monitored part of the light curve of HIP 80782 = HD 148379 = QU Nor with a time resolution of  1h

HIP 89956 = HD 168607 = V4029 Sgr, B9Ia⁺This hypergiant and LBV near quiescence, exhibits  Cyg-type variations discovered by Sterken (1977). Van Genderen et al. (1992, Paper IV), combining various data sets comprising 18 yr, found a possible quasi-period of 58.48d. The range amounts to 03.

The number of Hp data (Fig. 3 (click here)g) is too low, the overlap with the data sets mentioned above too small and the gaps in time of the Hp data too large to initiate a combined period analysis. Figure 13 (click here) shows the phase diagram for the Hp data constructed with the linear formula for the maxima presented in Paper IV. Evidently, maximum light lies between phase .1 and .6, while it should lie at phase .0. Thus the period certainly needs a revision, but this cannot be done with the present material.

  
Figure 13: The phase diagram for HIP 89956 = HD 168607 = V4029 Sgr

HIP 89963 = HD 168625 = V4030 Sgr, B5/8Ia⁺This object is presumably an LBV near quiescence according to Nota et al. (1996). It shows  Cyg-type variations discovered by Sterken (1977). Van Genderen et al. (1992, Paper IV) discussed various data sets and found a possible quasi-period lying between 33d and 37d. The range amounts to 015.

Because of the same reasons as for the previous variable, a combined period analysis of the partly overlapping data sets of Paper IV and the Hp data (Fig. 3 (click here)h) could not be undertaken. The periodogram of the Hp data alone, although presumably not of much weight, resulted in strong peaks near 39.4d, 32d and the presumably 2P aliases 79d and 65d, respectively. Therefore, we consider this result as a tentative support of the result presented in Paper IV that the quasi-period should be   35d.