Alderamin, definition and study. A-Z index of Cognitio.

Alderamin is a star in the constellation of Cepheus, about 49 light years from Earth.

Constellation, definition and study. A-Z index of Cognitio.

Constellation

It has about twice the mass and 1.5 times the diameter of the Sun and 18 times its brightness. Much more massive and warmer than the Sun, Alderamin appears to be a star in transition from the main sequence to a sub giant stage. Its position is strongly boreal and this means that the star is observable mainly from the northern hemisphere, where it is also circumpolar from most of the temperate regions; from the southern hemisphere its visibility is limited to the lower temperate regions and the tropical zone. This star is characterized by an unusually high rotation speed (246 km / s at the equator), approximately 125 times that of the Sun.

Sun, definition and study. A-Z index of Cognitio.

Sun

Normally, for stars of this mass, gravity tends to separate the lighter chemical elements from the heavier ones, concentrating the latter towards the core of the star, but in the case of Alderamin the high rotational speed seems to prevent the phenomenon. Electromagnetic activity also appears unusually high for a star of this spectral class. Alderamin, in fact, emits about the same amount of x-ray of the Sun. At present, the cause of these anomalies has not yet been clarified.

The name Alderamin is a contraction of the Arabic phrase “الذراع اليمين” which means “the right arm”, with the definite article transliterated in the Latin alphabet in “al” as usually happens for different names of stars of Arab origin. It is known as 天 鉤 五 (“the fifth star of the celestial sickle”) in Chinese astronomy.

Alderamin, definition and study. A-Z index of Cognitio.

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Alderamin, definition and study. A-Z index of Cognitio.

Alderamin