Multiplicity of Galactic Cepheids from long-baseline interferometry – III. Sub-percent limits on the relative brightness of a close companion of δ Cephei

By A. Gallenne, A. Mérand, Pierre Kervella, J. Monnier, G. Schaefer, R. Roettenbacher, W. Gieren, G. Pietrzyński, H. Mcalister, T. T. ten Brummelaar and 4 more. 2016

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We report new CHARA/MIRC interferometric observations of the Cepheid archetype $\delta$ Cep, which aimed at detecting the newly discovered spectroscopic companion. We reached a maximum dynamic range $\Delta H $ = 6.4, 5.8, and 5.2 mag, respectively within the relative distance to the Cepheid $r 9.15, 8.31$ 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, the companion has to be located at a projected separation $< 24$ mas with a spectral type later than a F0V star.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/b5d865aa9614034b3b1554bbc328c45b00661e21