Variable stars

We now know that the stars belonging to many distant nebula, there are variable stars, surprisingly changing its luster. Their luster changes strictly periodically, subject to a certain law. It made an important discovery that the period of light variation depends on the true brightness of a star. That is, the variable is called a star, which changes brightness were reliably detected at that level observation technology. For assignment to the category of variable stars is enough to shine it at least once undergone change.

We now know that the stars belonging to many distant nebula, there are variable stars, surprisingly changing its luster

Variable stars are very different from each other. Brightness changes may be periodic. The main characteristics are observational period, the amplitude of the light changes, the shape of the light curve.

The reasons for changes in star brightness can be activity of the chromosphere, periodic eclipses of stars in a binary system, the flow of material from one star to the other, a supernova explosion...

The first variable star was picked in 1638. Then Johann Holvard noticed that the star Mira pulsates with a period of 11 months. The second variable star, which was described in 1669 Geminiano Montanari became eclipsing variable Algol. By 1786, there were already 10 known variable stars. The publication of the General Directory (2008) listed more than 46,000 variable stars in our galaxy.

Variable stars are designated by the letters R to Z in the order of detection in each constellation. For example, R Hydrae - first on the opening time variable star in the constellation Hydra, S Hydrae - Two...

These variable stars make it possible to measure distances. Suppose that in the nebula have variable stars. In the period of light variation, we can learn their true brightness. Then we will define their apparent brightness and as a result find the distance to the stars.

Thus, variable stars - is the key to the boundless dimensions of the distances between the "islands" of the universe.

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