1. Multiplicity of Galactic Cepheids from long-baseline interferometry - III. Sub-percent limits on the relative brightness of a close companion of δ Cephei.
- Author
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Gallenne, A., Mérand, A., Kervella, P., Monnier, J. D., Schaefer, G. H., Roettenbacher, R. M., Gieren, W., Pietrzyński, G., McAlister, H., ten Brummelaar, T., Sturmann, J., Sturmann, L., Turner, N., and Anderson, R. I.
- Subjects
CEPHEIDS ,ASTRONOMICAL photometry ,ASTRONOMICAL observations ,INTERFEROMETRY ,STELLAR parallax ,MULTIPLICITY of nuclear particles - Abstract
We report new CHARA/Michigan InfraRed Combiner interferometric observations of the Cepheid archetype δ Cep, which aimed at detecting the newly discovered spectroscopic companion. We reached a maximum dynamic range ΔH = 6.4, 5.8 and 5.2 mag, respectively, within the relative distance to the Cepheid r < 25 mas, 25 < r < 50 mas and 50 < r < 100 mas. Our observations did not show strong evidence of a companion. We have a marginal detection at 3s with a flux ratio of 0.21 per cent, but nothing convincing as we found other possible probable locations. We ruled out the presence of companion with a spectral type earlier than F0V, A1V and B9V, respectively for the previously cited ranges r. From our estimated sensitivity limits and the Cepheid light curve, we derived lower limit magnitudes in the H band for this possible companion to be H
comp > 9.15, 8.31 and 7.77 mag, respectively, for r < 25 mas, 25 < r < 50 mas and 50 < r < 100 mas. We also found that to be consistent with the predicted orbital period (Anderson et al.), the companion has to be located at a projected separation <24 mas with a spectral type later than an F0V star. [ABSTRACT FROM AUTHOR]- Published
- 2016
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