Doon

Boxus a (hereafter Doon) is a gas giant orbiting extremely close to its host star. Doon’s orbit is nearly circular and stable around Boxus A.

From Boxus c (Dari): The foolish and curious who stare into the blinding visage of Boxus may occasionally notice a dark spot move across its equator. The finest astronomers of Dari theorize that this may not be an element of Boxus itself, but rather a far off terrestrial body keeping close company to Boxus which has been tentatively named “Doon”. Very few who are not familar with astronomy are aware of Doon and no known cultures of Dari have mention of it in their lore.