About 56 Algol variables were known in 1907; the variables of this class are the most difficult to detect, for the short period of obscuration may easily escape notice unless the star is watched continuously.
Algol gives a helium-spectrum which undergoes no alteration at minimum.
Algol is ordinarily of magnitude 2.3, but once in a period of 2d.
Algol, in fact, travels at the rate of 26.3 miles a second round the centre of gravity of the system which it forms with an invisible companion, while the two together approach the sun with an unvarying speed of 2.3 miles per second.
For the Algol variables it is possible to form even more direct calculations of the density, for from the duration of the eclipse an approximate estimate of the size of the star may be made.
If these suppositions have a basis of reality, the proper motion of Algol should be disturbed by a small, but measurable undulation, corresponding to the projection of its orbit upon the sky; and although certainty on the point cannot be attained for some years to come, Lewis Boss regarded the evidence available in 1895 as tending to confirm Dr Chandler's theory.6 Proceedings Amer.
In the Algol variables one of the component stars is dark (that is to say, dark in comparison with the other), and once in each revolution, passing between us and the bright component, partially hides it.
It differs from the Algol type in having two unequal minima separated by two equal maxima.
Roberts concluded in this way that the average density of the Algol variables and their eclipsing companions is about one-eighth that of the sun.
Stars of the class to which the Algol type of variables belongs will appear to us to vary only in the exceptional case when the plane of the orbit passes so near our sun that one body appears to pass over the other and so causes an eclipse.
The dimensions of the Algol system have been calculated, with the result that Algol appears to have'a diameter of 1,000,000 m.
The light of Algol remains constant during close upon 56 hours; then declines in 62 hours (approximately) to nearly one-fourth its normal amount, and is restored by sensibly the same gradations.
The period of Algol, as measured by its eclipses, is subject to complex irregularities.
This leaves no room for doubt that an invisible companion passes between us and Algol about the time the diminution of light takes place, and so proves the correctness of the explanation.
This smacks of hysteria - Ceres was discovered conjunct ALGOL.
This talk presents a novel semantics for Idealized ALGOL using games, which is quite unlike traditional denotational models of state.
Variables of the Algol class are rendered difficult to discover by the incidental character of their fluctuations.
Vogel of Potsdam, by repeated measurements of the motion of Algol in the line of sight, showed that the star is always receding from us before the loss of light and approaching us afterwards.