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Southward of the the Circlet in Pisces, and close to the Ecliptic as it passes through Aquarius, lies a group of three comparatively faint stars. These stars share the designation 'Psi Aquarii', though in fact they are entirely unrelated to one another, apart from the fact that they fall close to the same line of sight as seen from Earth. Psi2 is the most distant of the three at some 300* light years from the Solar System, which places it more than twice as far away as Psi1, the nearest of the three.

Psi2 Aquarii is a blue star of the class known as 'Be stars', or more precisely in this case 'periodic Be stars', as its magnitude shows a slight but regular variation over a period of almost exactly a day. The star, which is more than four times the Sun's diameter, rotates very rapidly on its axis, and erupts material into space as it does so. This erupted matter forms a circumstellar disc that extends outwards to form a ring surrounding the star itself.


* Many sources quote a distance of about 400 light years for this star, but more recent analysis from the Gaia mission data suggests that it is rather closer to the Solar System than previously thought.

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