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Astron. Astrophys. 351, 267-272 (1999)


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ET And, HD 219891, or HD 219668 - which one shows short-term variability?

H. Lehmann 1, G. Scholz 2, G. Hildebrandt 2 and K. Panov 3

1 Thüringer Landessternwarte Tautenburg, 07778 Tautenburg, Germany (lehm@tls-tautenburg.de)
2 Astrophysikalisches Institut Potsdam, Telegrafenberg, 14473 Potsdam, Germany (gscholz, ghildebrandt@aip.de)
3 Institute of Astronomy, Sofia, Bulgarian Academy of Sciences, Bulgaria (kpanov@astro.bas.bg)

Received 31 December 1998 / Accepted 18 June 1999

Abstract

The result of recent photometric observations of the CP star ET And, published by Weiss et al. (1998), shows that the known brightness variation of about 145 min has to be obviously assigned to the comparison star HD 219891. In order to test this statement we investigate the Hipparcos photometry of ET And, HD 219891 and the check star, HD 219668, on the existence of pulsations. The significance of peaks found in the periodograms is estimated using empirically determined false alarm probability distributions derived from a large number of synthetic data sets. Results show that the probability of large peaks produced in the periodograms by only noise cannot be described by the well-known statistics valid for an evenly spaced time sampling. In the photometry of ET And we find a period of [FORMULA] with a false alarm probability of 6% or less. For the two comparison stars we could not detect any signal in the data.

Key words: stars: binaries: spectroscopic – stars: chemically peculiar – stars: individual: ET And – stars: oscillations

Send offprint requests to: H. Lehmann

© European Southern Observatory (ESO) 1999

Online publication: November 2, 1999

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