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Absolute dimensions and masses of eclipsing binaries. IV - EE Pegasi is a triple star
Lacy, C. H.; Popper, D. M.
AA(Arkansas, University, Fayetteville, AR), AB(California, University, Los Angeles, CA)
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 281, June 1, 1984, p. 268-275. NSF-supported research. (ApJ Homepage)
Publication Date:
NASA/STI Keywords:
Eclipsing Binary Stars, Stellar Magnitude, Stellar Mass, Stellar Rotation, Stellar Spectra, Triple Stars, Radial Velocity, Stellar Evolution, Stellar Luminosity, Stellar Spectrophotometry
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A previously unknown faint companion with an orbital period of about 4 years has been discovered orbiting the 2.6 day eclipsing binary in the EE Pegasi system. The third star was discovered by its effects on the radial velocities and times of primary eclipse of the eclipsing pair. Spectroscopic orbits derived from a three-body fit to the radial velocities have been combined with photometric orbits from photoelectric light curves to find very accurate masses and radii for components of the eclipsing binary: (2.15 + or - 0.02 solar masses, 2.09 + or - 0.03 solar radii) for the A3m primary and (1.33 + or 0.01 solar masses, 1.31 + or - 0.01 solar radii) for the F5 secondary. Theoretical evolutionary tracks indicate an age of about 3 x 10 to the 8th years based on the observed masses, radii, and luminosities. The F5 secondary of the eclipsing pair is still very close to the zero-age main sequence. The A3m primary is about halfway through its main sequence lifetime. Both are rotating synchronously with the orbital period. The third star is probably a low-mass main-sequence star of spectral type K or M.

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