EDP Sciences
Free access
Volume 446, Number 2, February I 2006
Page(s) 583 - 589
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20053032
A&A 446, 583-589 (2006)
DOI: 10.1051/0004-6361:20053032

The new orbital elements and properties of $\vec{\varepsilon}$ Persei

J. Libich1, 2, P. Harmanec1, 2, J. Vondrák3, S. Yang4, P. Hadrava2, C. Aerts5, 6, P. De Cat7, P. Koubský2, P. Skoda2, M. S lechta2, K. Uytterhoeven2, 5 and P. Mathias8

1  Astronomical Institute of the Charles University, V Holesovic kách 2, 180 00 Praha 8, Czech Republic
    e-mail: [liba;hec]@sirrah.troja.mff.cuni.cz
2  Astronomical Institute, Academy of Sciences of the Czech Republic, Fricova 298, 251 65 Ondrejov, Czech Republic
    e-mail: [libich;hec;had;koubsky;skoda;slechta;katrienu]@sunstel.asu.cas.cz
3  Astronomical Institute, Academy of Sciences of the Czech Republic, Bocní II/1401a, 141 31 Praha 4, Czech Republic
    e-mail: vondrak@ig.cas.cz
4  Dept. of Physics and Astronomy, University of Victoria, PO Box 3055, Victoria, B.C., V8W 3P6 Canada
    e-mail: yang@beluga.phys.uvic.ca
5  Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium
    e-mail: [conny;katrienu]@ster.kuleuven.be
6  Department of Astrophysics, "Radboud University Nijmegen", PO Box 9010, 6500 GL Nijmegen, The Netherlands
7  Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium
    e-mail: peter@ksb-orb.oma.be
8  Observatoire de la Côte d'Azur Département GEMINI, UMR 6203, 06304 Nice Cedex 4, France
    e-mail: mathias@obs-nice.fr

(Received 9 March 2005 / Accepted 18 July 2005 )

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 $\varepsilon$ Per binary. Observations covering a time interval of about 37 000 days (101.3 years) can be reconciled with a constant orbital period of 14$\fd$06916$\,\pm\,$0$\fd$00004. The high orbital eccentricity of 0.555$\,\pm\,$0.009 was also confirmed. New spectral observations confirm that there is a periodic variation of the systemic velocity. Together with new evidence from astrometric observations (also analyzed here), they confirm the existence of a third body in the system with an orbital period of about 9600 days (26.3 years), rather than 4156 days, as reported earlier. Application of the disentangling technique to the H$\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°, the observed mass function implies a mass of the secondary M2=0.85-1.77 $M_{\odot}$, if a primary mass is adopted of 13.5$\,\pm\,$2.0 $M_{\odot}$. Attempts to detect the third body via interferometric observations should continue in spite of this first negative result.

Key words: stars: early-type -- stars: binaries: spectroscopic

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