German astronomer who discovered spectroscopic binary stars.
By measuring the Doppler effect in the spectral lines of stars to ascertain
their velocity, he ended the controversy over the value of Christian
Doppler's theory for investigating motion in the universe.
Vogel was born and educated in Leipzig and in 1863 began working at
the observatory there. From 1882 he was director of the Potsdam Observatory
Vogel worked intensively on the spectroscopic properties of planets,
nebulae, the northern lights, comet III 1871, and the Sun, and examined
the spectra of some 4,000 stars. He used spectrophotometry to study
Nova Cygni in 1876 and his results provided the first evidence that
changes occur in the spectrum of a nova during its fading phase.
Vogel's discovery of spectroscopic binary stars arose from a study of
the periodic displacements of the spectral lines of the stars Algol
and Spica, eclipsing binary stars whose components could not, at the
time, be detected as separate entities by optical means. From his spectrographs,
Vogel derived the dimensions of this double star system, the diameter
of both components, the orbital velocity of Algol, the total mass of
the system and in 1889, he derived the distance between the two component
stars from each other.