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"Peremennye Zvezdy", Prilozhenie, vol. 10, N 33 (2010)

NSV 07340, a New RR Lyrae Variable with Equidistant Triplet of Frequencies

S. V. Antipin^#1,2, E. V. Kazarovets^#2, E. N. Pastukhova^#2

#1 Sternberg Astronomical Institute, Moscow, Russia; #2 Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia

ISSN 2221–0474

Received:   13.12.2010;   accepted:   14.12.2010
(E-mail for contact: antipin@sai.msu.ru, helene@inasan.ru, pastukhova@sai.msu.ru)

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Star Name: NSV 07340, TYC 3060 01159 1, 1SWASP J15545855+424610.4, NSVS 5177040, NSVS 5225507 Coordinates (J2000): 15 54 58.55, +42 46 10.5 Variability type: RRC;   Limits, System: 10.97–11.56 (WASP mag); 11.32–11.64 (R, NSVS) ;   Spectrum: A2 Period: 0.317152 d;   Epoch: JD 2454189.697

Remarks:

The variable was discovered by Zinner (1936), but the nature of its variability remains unknown to date. We analyzed all available observations of NSV 07340 from the NSVS/ROTSE-I (Wozniak et al. 2004) and SuperWASP (Butters et al. 2010) online public archives. Three frequencies, the first-overtone mode accompanied by two additional almost equidistant oscillations, were found both in NSVS and WASP data: WASP Period, day WASP Semi-amplitude, mag NSVS Period, day NSVS Semi-amplitude, mag f1 0.317152 0.139 0.31711 0.105 f2 0.320340 0.066 0.32034 0.053 f3 0.314355 0.038 0.31435 0.040 f3–f1 = 0.028 c/d, f1–f2 = 0.031 c/d. Note that we used not all 9007 but 8700 SuperWASP observations because of a number of erroneous data points, some of them possibly due to bad weather conditions during parts of nights in the WASP observational set. One more period, 29.79 days (that appears in the power spectra along with several 1-day aliases, at frequencies about 2, 3 and 4 c/d, see the bottom spectrum for WASP observations in the Figure), probably results from variable sky background brightness due to Moon phases. Similar peculiar RR Lyrae variables have been known in the LMC (Alcock et al. 2000); a star of the same kind has been recently reported in the Galaxy (Khruslov 2010). The probable origin of the frequency triplet is excitation of two non-radial oscillations in a close vicinity of the first-overtone mode. Acknowledgments: Our studies are supported by grants from the Russian Foundation for Basic Research and by the Program "Origin and Evolution of Stars and Galaxies" of the Presidium of Russian Academy of Science. Thanks are due to Dr. N.N. Samus for useful discussion of the results.

References:

Alcock, C., Allsman, R., Alves, D.R., et al., 2000, Astrophys. J., 542, 257 Butters, O.W., West, R.G., Anderson, D.R., et al., 2010, Astron. and Astrophys., 520, L10 Khruslov, A.V., 2010, Perem. Zvezdy Prilozh., 10, No. 32 Wozniak, P.R., Vestrand, W.T., Akerlof, C.W., et al., 2004, Astron. J., 127, 2436 Zinner, E., 1936, Astron. Nachr., 258, 315