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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