Sunday, 18 June 2017

Nu Scorpii: the 'double double'

The writer has always enjoyed viewing double stars, particularly if they are ‘tight’ ones: that is, close pairs that are hard to separate. Although my ‘scopes are not dedicated to the task, ‘tricks’ like using aperture masks and simple orthoscopic eyepieces will often succeed, though the most important factor is steady seeing, that usually occurs later at night.

A favourite example is the ‘double-double’ Nu Scorpii, aka “Jabbah” (Arabic for the Scorpion’s forehead) close to bright star Beta Sco, refer to star maps (P82, Astron 2017). A ‘double-double’ is a quaternary system with two pairs of stars gravitationally bound in a four-star system. As Agnes Clerke wrote (1905): it is “perhaps the most beautiful quadruple group in the heavens.”