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Double-line Spectroscopic Binary

(Double-lined Spectroscopic Binary)
(spectroscopic binary star where a specific line shows up at two different wavelengths)

A Double-line Spectroscopic Binary (or Double-lined Spectroscopic Binary) is a Spectroscopic Binary star system in which the (combined) spectrum shows a specific Spectral Line of some Element twice, the variation in Wavelength implying a Doppler Shift indicating stars' relative Radial Velocity.

This is in contrast to a Single-line Spectroscopic Binary (or Single-lined Spectroscopic Binary), where some line varies, indicating the radial motion of an orbit around a companion, but no line is observed that clearly comes from the companion. This latter is identical to identification of Extra-Solar Planets via the radial velocity method, the distinction being the smaller mass of a planet companion. A Spectral Resolution insufficiently precise to identify planets can still identify many Binary Stars by this method.

(star type,binary star type,spectrography)

Referenced by:
Beta Centauri
DQ Tau
Spectroscopic Binary
Stellar Parameter Determination