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Ji Su Si（Sagittarius η，η Sgr）Is located inSagittariusOne ofStellar system, Distanceearthone hundred and forty-nineLight year。In the Bayer classification, the centaur η was also“Telescope pedestalβ”。
Its main star, η A Sagittarius, is aM3.5 typeRed Giant。It is aVariable star, so itsApparent magnitudeWill change between+3.08 and 3.12, and will be classified asIrregular variable star。The bright star in the companion star Sagittarius η B is aF-type dwarf, apparent magnitude is+7.77.It is 165 away from the main starAstronomical unitThe revolution period is about 1300 years.The distance between two stars in the night sky is 3.6Angular second。There are also two darker companion stars: η C Sagittarius, with an apparent magnitude of 13, 33 angular seconds from the main star;Sagittarius η D, apparent magnitude 10, 93 angular seconds away from the main star.
