The Highly Eccentric Binary HD 2909

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Session 6 -- Binary Stars
Display presentation, Monday, 30, 1994, 9:20-6:30

[6.02] The Highly Eccentric Binary HD 2909

T. Mazeh (Lab. Astroph., NASM; Wise Obs., Tel Aviv U.), S. Zucker, D. Goldberg (Wise Obs., Tel Aviv U.), D.W. Latham, R.P. Stefanik (CfA), B.W. Carney (UNC)

TODCOR is a new two-dimensional correlation technique to extract the radial velocities of the two components of double-line spectroscopic binaries. In this work we apply TODCOR for the first time to a real system --- the highly eccentric binary HD 2909. TODCOR has derived successfully the velocities of the two components, even at phases when the velocity difference between the primary and the secondary was very small.

We present an orbital solution which shows that HD 2909 is a spectroscopic binary with a period of 2127 days and an eccentricity of $0.951 \pm 0.002$. This value is second only to the highest eccentricity known for a spectroscopic binary --- $0.9752 \pm 0.0003$, which was recently found by Duquennoy et al. (A\&A, 254, L13, 1992) for Gls 586A. The discovery of the high eccentricity of Gls 586A and HD 2909 raises some interesting questions with regard to the tidal evolution of such systems. These questions and the tidal history of HD 2909 are discussed. We show that the tidal interaction of HD 2909 was not strong enough to produce throughout the system lifetime any substantial change in the semimajor axis and the eccentricity of the orbit, nor in the stellar rotation.

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