Premium
The chromospherically active binary star EI Eridani: I. Absolute dimensions
Author(s) -
Washuettl A.,
Strassmeier K.G.,
Granzer T.,
Weber M.,
Oláh K.
Publication year - 2009
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200811040
Subject(s) - physics , astrophysics , parallax , radius , luminosity , orbital inclination , radial velocity , orbit (dynamics) , binary star , astronomy , star (game theory) , binary number , stars , computer security , arithmetic , mathematics , galaxy , computer science , engineering , aerospace engineering
We present a detailed determination of the astrophysical parameters of the chromospherically active binary star EI Eridani. Our new radial velocities allow to improve the set of orbital elements and reveal long‐term variations of the barycentric velocity. A possible third‐body orbit with a period of ≈19 years is presented. Absolute parameters are determined in combination with the Hipparcos parallax. EI Eri's inclination angle of the rotational axis is confined to 56°.0 ± 4°.5, ist luminosity class IV is confirmed by its radius of 2.37 ± 0.12 R ⊙ . A comparison to theoretical stellar evolutionary tracks suggests a mass of 1.09 ± 0.05 M ⊙ and an age of ≈ 6.15 Gyr. The present investigation is the basis of our long‐term Doppler imaging study of its stellar surface (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)