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The Companions of the Classical Cepheid FF Aql

Published online by Cambridge University Press:  12 April 2016

Nancy Remage Evans  and
Andrej Udalski
Nancy Remage Evans
Affiliation:
Institute for Space and Terrestrial Science, York University, c/o CRESS, 4700 Keele St., North York, M3J 1P3 Ontario, Canada
Andrej Udalski
Affiliation:
Institute for Space and Terrestrial Science, York University, c/o CRESS, 4700 Keele St., North York, M3J 1P3 Ontario, Canada

Abstract

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We have obtained CCD photometry of the classical Cepheid FF Aql and the companion 6″ away to determine whether they are likely to be physically associated. Because the Cepheid is 5 magnitudes brighter than the companion, the measurements are difficult. The values we find for the companion are V = 11.14 ± 0.07 mag, B – V = 0.60 ± 0.05 mag and V – R = 0.39 ± 0.04 mag. If the companion were at the same distance as the Cepheid, its absolute magnitude would be MV = 2.58 mag, corresponding a spectral type of approximately A8 V. The observed (B – V)0 corresponds to a spectral type of F4 V to F5 V. The observed color and spectral type are incompatible with a ZAMS magnitude of the companion at the distance of the Cepheid.

Positional measures indicate that there may be relative motion between the two stars, which would be too large to be orbital motion. We conclude that the 6″.8 companion is not a member of the FF Aql system. Information about the four stars in the direction of FF Aql is summarized.

Type
Classical Methods, Catalogs, & Databases
Information
International Astronomical Union Colloquium , Volume 135: Complementary Approaches to Double and Multiple Star Research , 1992 , pp. 314 - 316
Copyright
Copyright © Astronomical Society of the Pacific 1992

References

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