COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3014 Konkoly Observatory Budapest 21 April 1987 HU ISSN 0374-0676 PHOTOGRAPHIC OBSERVATIONS OF THE PLANETARY NEBULA PK 215 +3d 1 The planetary nebula PK 215 +3d 1 (NGC 2346) is a butterfly bipolar nebula. The central star (AGK3 - 00965) was known as a single-line spectroscopic binary. This star had been observed frequently, and no brightness variations were noticed before 1981. In 1982 Kohoutek (1982) found that the brightness of the central star had dramatic changes after November 1981, showing a light curve of an eclipsing binary with a period of 15.957 and an amplitude of 2-3m. Later Mendez et al. (1982) proposed that the eclipses were caused by a dark dust cloud, which circulated around the system. Some other authors have revealed fast and complex variations in the light curves. We observed the planetary nebula NGC 2346 using the 40/200 cm double astrograph of the Peking Observatory Xing-Luing station from April 1981 to April 1986. The plates used were Kodak Eastman 103aO and IIaO and the selected area SA 98 was used to the magnitude calibration. The plates were measured with a microphotometer. The magnitudes in Table I contain contributions from both the central star and the nebular radiations. From these observations (see Figure 1) the following conclusions can be made: 1. The observations in 1985 show that the central star of the planetary nebula of NGC 2346 has still obvious "eclipsing" variations with an amplitude of about 3.5 mag., the current elements being: Min. Hel. = J.D. 2446153.2 + 15.957d*E 2. From the observations of 1986 we can see that the minimum of the light curve has increased by about 2-3 mag., so that the amplitude of the variation has been reduced to ~= 1.1 m; the "eclipsing" variability of the star is not obvious in 1986. [FIGURE 1] Figure 1: Light curves of AGK3 - 00965. Phases were computed using the elements given above. The 1985 Sept. observations of Jasniewicz and Acker (1986) are in between our 1985 and 1986 observations and strenghten the conclusion about the decreasing amplitude of the star. Table I. No. Plate No. J.D. hel. m No. Plate No. J.D. hel. m DA 2440000+ pg DA 2440000+ pg 1 2829 4724.054 10.91 23 4066 6170.051 14.05 2 3147 4988.024 11.22 24 4067 6171.006 13.52 3 3168 5049.021 10.94 25 4068 6172.078 13.05 4 3206 5078.029 11.33 26 4071 6174.054 11.61 5 3681 5414.054 12.60 27 4079 6178.041 10.90 6 3948 5980.354 13.22 28 4080 6179.045 11.42 7 3969 6026.360 11.36 29 4266 6443.238 10.87: 8 3994 6094.184 10.86 30 4417 6490.003 10.75 9 4005 6095.153 11.17 31 4418 6490.989 10.50 10 4012 6111.172 11.74 32 4419 6491.996 10.20 11 4038 6139.046 12.40 33 4420 6493.007 10.12 12 4041 6139.976 12.58 34 4421 6494.030 10.73 13 4044 6140.976 12.18 35 4422 6495.026 10.48 14 4046 6141.976 11.95 36 4414 6497.000 10.98 15 4049 6142.986 11.70 37 4415 6499.042 10.86: 16 4051 6143.979 10.88 38 4410 6501.044 11.03 17 4053 6146.052 10.48 39 4412 6503.036 10.95 18 4057 6150.030 11.98 40 4413 6521.037 11.09 19 4075 6152.052 13.33 41 4411 6522.008 11.36 20 4061 6166.010 11.60 42 4416 6527.001 10.72 21 4064 6167.040 13.24 43 4430 6531.033 11.14 22 4065 6168.003 14.00: 44 4428 6532.025 10.92 45 4429 6533.055 11.12 We can say that the variations of the central star of the planetary nebula NGC 2346 will disappear gradually soon, and the brightness of the star will return to the stable phase as it was before 1981. HAO XIANG-LIANG Beijing Astr. Obs. Academia Sinica Beijing, China References: Jasniewicz, G. and Acker, A., 1986, Astron. Astrophys. 160.L1 [BIBCODE 1986A&A...160L...1J ] Kohoutek, L., 1982, IAU Circ. No. 3667 [BIBCODE 1982IAUC.3667....2K ] 1982, IBVS No. 2113 Mendez, R.H., Gathier, R., Niemela, V.S., 1982, Astron. Astrophys. 116.L5 [BIBCODE 1982A&A...116L...5M ]