COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2362 Konkoly Observatory Budapest 30 June 1983 HU ISSN 0374-0676 ON THE VARIABILITY OF THE CENTRAL STAR OF THE PLANETARY NEBULA NGC 1514 The central star of the planetary nebula NGC 1514 (PK 165 - 15.1) is much too luminous relative to the nebula. The spectral type is too late considering the high excitation in the nebula. These facts and the observed UV excess (Kohoutek 1967; Kohoutek and Hekela 1967; Liller and Shao 1968) suggest the presence of a much hotter second component. Also the idea that these two stars form a physical pair is generally accepted, some doubt remains because of partly contradictory radial velocity observations (Kohoutek 1968; Mammano et al. 1968; Greenstein 1972; Acker 1976). The number of published photometric measurements is small. Some of the observers have suggested variability. Kohoutek (1966) derived a longterm brightness increase of about -0.005m/year. Arkhipova (1968) found no variations larger than +- 0.01m in V and B and +- 0.025m in U during some observing runs ranging from 10 minutes up to several hours. Lawrence et al. (1967) suspect periodic oscillations of 138 and 855 sec. During 31 nights covering the period between January 1982 and March 1983 we collected about 350 V measurements of this object with the single-channel photoelectric photometer attached to the 24 inch RC telescope of the L.Figl Observatory. An aperture of 20 arcsec was used, his limited the nebular contribution to less than 1% of the total light and was therefore ignored. Each V magnitude per night consisted of the average of 5 to 6 15 sec integrations. During a few nights the star was monitored continously for a few hours to look for short-term variations. Table I gives the identification of the observed stars. Table I ------------------------------------------------------------------ Object BD SAO V B - V Sp ------------------------------------------------------------------ Central Star of NGC 1514 +30d623 057020 9.42^+) 0.55^+) K0 Comparison Star +30 621 057017 8.41 0.87 K0 Check Star +30 624 057021 8.19 1.46 ------------------------------------------------------------------ ^+)Data from Liller and Shao The mean of all measurements is DeltaV (central star - comparison star) = 1.0131m +- 0.0045 st.d. DeltaV (comparison star - check star) = 0.2260m +- 0.0039 st.d. These two standard deviations for single measurements are practically identical suggesting constancy of the central star during the observed period. We checked for short-term variability by analysing the longest run of 5 hours applying Fourier methods. The program used has been described by Breger (1982). Practically the power spectrum is flat. The highest peak of 0.0017m amplitude with a frequency of 154 sec is not regarded as significant. The oscillations of 138 and 855 sec as suggested by Lawrence et al. could not be found in our data. We want to thank M. Breger for valuable help concerning his program. A. PURGATHOFER A. SCHNELL Institute for Astronomy University of Vienna Turkenschanzstrasse 17 A-1180 Vienna, Austria References: Acker, A.: 1976, Publ.Obs.Strasbourg 4, fasc. 1 [BIBCODE 1976POStr...4....1A ] Arkhipova, V.P.: 1968, Astron.Zh. 45, 1312 [BIBCODE 1968AZh....45.1312A ] Breger, M.: 1982, Vienna Internal Report 1982/2 Greenstein, J.L.: 1972, Astrophys.J. 173, 367 [BIBCODE 1972ApJ...173..367G ] Kohoutek, L.: 1966, Bull.Astron.Inst.Czechoslovakia 17, 318 [BIBCODE 1966BAICz..17..318K ] Kohoutek, L.: 1967, Bull.Astron.Inst.Czechoslovakia 18, 103 [BIBCODE 1967BAICz..18..103K ] Kohoutek, L.: 1968, IAU Symp. No. 34, 324 [BIBCODE 1968IAUS...34..324K ] Kohoutek, L., Hekela, J.: 1967, Bull.Astron.Inst.Czechoslovakia 18, 203 [BIBCODE 1967BAICz..18..203K ] Lawrence, G.M., Ostriker, J.P., Hesser, J.E.: 1967, Astrophys.J. 148, L 161 [BIBCODE 1967ApJ...148L.161L ] Liller, W., Shao, C. Y.: 1968, IAU Symp. No. 34, 320 [BIBCODE 1968IAUS...34..320L ] Mammano, A., Margoni, R., Perinotto, M.: 1968, IAU Symp. No. 34, 329 [BIBCODE 1968IAUS...34..329M ]