Orbital parameters of the inner binary system of the δ Cephei system
An inner companion has recently been discovered orbiting the prototype of classical Cepheids, δ Cep, whose orbital parameters are now reported.
The orbital parameters of the δ Cep inner binary system determined using 2019 HARPS-N spectroscopic data
N. Nardetto, V. Hocdé, P. Kervella, A. Gallenne, W. Gieren, D. Graczyk, A. Merand, M. Rainer, J. Storm, G. Pietrzyński, B. Pilecki, E. Poretti, M. Bailleul, G. Bras, A. Afanasiev
We collected new precise radial velocity (RV) measurements of δ Cep in 2019 using the HARPS-N spectrograph mounted at the 3.58-m Telescopio Nazionale Galileo, La Palma, Spain. These RV measurements, compared with RV templates available in the literature, allowed us to derived the orbital parameters of the system: orbital period Porb = 9.32 years, eccentricity e = 0.71, a semimajor axis a = 0.029 arcsec, and a center-of-mass velocity V0 = −17.28 km/s, among other parameters.
The resulting orbital parameters of the δ Cep inner binary system and a cleaned RV curve of the pulsation of the star will be used to study its Baade–Wesselink projection factor in a future publication.
