Vampirism under stars

The so-called blue watchdogs have saved their youth by deducting vampary matter from their companions

Already many years ago astronomers has noticed a certain type of star, which it was not allowed to give: the so-called "Blue watchlet" find usual in clusters of the same as the same time created at the same time (in May, a renewed evaluation of alter pictures of the space telescope Hubble showed that even in the center of the milk strain a few of them "Life"To). They are brighter and their spectrum is blue than that of their neighbors, so they work under their siblings like later born babies, just watchful.

Artistic representation of the emergence of a blue watchlect: The actually smaller star withdraws the ages and coarse red huge matter, thus growing itself and becomes apparently young.

Because they can, one analyzes their physical data, not be born at the same time – otherwise they had to be removed from the main series of the Hertzprung-Russel chart and developed to red giants. Because just the particularly heavy, bright stars of the main series move your powder (helium) first. Already in 1953, the US astronomer Allan Sandage has noticed when he constructed a Herrzprung-Russel diagram of the ball star M3.

Try this contradiction to explain two different theories. On the one hand, the blue watchlier could be created by the collision of two stars. Binary and especially threesome systems are particularly consistent because they give a better destination. The result is usually a gross blue star with a dwarf as a companion. In fact, observations show that the impossible sky objects have relatively often smaller companions.

However, the probability of such interbreeds decreases, the looser the members of the star cluster are grouped. A second, competitive theory therefore tries another explanation. Binary systems, in the star world quite frequently, usually consist of objects of different coarse. If a twin of parches is particularly rough, it takes the development to the red giant first.

In this process he expands strongly, his density decreases. That affects him fatal: If the two stars are close enough, he can now escape his neighbor alone through the gravitation material. The more about it over the other star, the stronger speeds the process. In the end we have a for his old unusual and rough star in front of us, who must be kept because of his properties of the astronomers for young. He is again accompanied by a dwarf.

The survey of the companions

Since the result in both cases is the same – age star guy in his second youth, which is circle from a blond asterisk – alone the observation of women’s dwarfs is not enough to clear the true origin of the blue watchlier. The astronomers Aaron Geller and Robert Mathieu from the University of Wisconsin have therefore greeted something more accurately – in the science magazine Nature Report from your findings. If the old guy did not betray nothing, one sometimes comes through the question of his companions to the goal – the researchers have considered the mass distribution of the senior dwarfs, which circle the blue watchlear.

As a study object, the open star cluster NGC 188 served in the constellation Kepheus, which is 6.4 billion years old and consists of around 5,000 members. Two observations are interesting: On the one hand, most of the considered systems have very short circulation times. On the other hand, the senior dwarfs observed here are very easy with less than a sunbathing. Both facts can, which are the researchers, serve well as a distinguishing criterion: The few blue watches created by a collision slowly turn with their relatively heavy companion slowly around the center of gravity, while the stars rejuvenated by vampirism stars their light companions quickly around themselves.

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