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Description
A detailed analysis of a large collection of electronic spectra from three observatories, together with radial velocities published earlier, were used to derive a new ephemeris and improved orbital elements for the eps Per binary. Observations covering a time interval of about 37000-days (101.3-years) can be reconciled with a constant orbital period of (14.0691+/-0.00004)-days. The high orbital eccentricity of 0.555+/-0.009 was also confirmed. New spectral observations confirm that there is a periodic variation of the systemic velocity. Together with new evidence from astrometric observations (also analyzed here), they confirm the existence of a third body in the system with an orbital period of about 9600-days (26.3-years), rather than 4156-days, as reported earlier. Application of the disentangling technique to the H alpha spectra with good S/N ratios did not allow detection of spectral lines of either the secondary or tertiary components. For plausible inclinations between 30 and 90 {deg}, the observed mass function implies a mass of the secondary M_2_=0.85-1.77M_{sun}_, if a primary mass is adopted of (13.5+/-2.0)M_{sun}_. Attempts to detect the third body via interferometric observations should continue in spite of this first negative result.
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