IRAS 23166+1655 is thought to be a preplanetary nebula surrounding LL Pegasi (AFGL 3068), a binary system that includes an extreme carbon star. The pair is hidden by the dust cloud ejected from the carbon star and is only visible in infrared light.[1]
The nebula displays an unusual spiral shape. The shape is thought to be formed through the interaction between the stellar companion and the carbon star, as has been seen in other binary systems, although not with such a precise geometric form. [2] The distance between spiral layers is consistent with estimates of the pair's orbital period based on their apparent angular separation. Its position is RA 23 19 12, Dec +17 11 35. [3] Some say that, due to the regular appearance of spiral arms, the orbital period between LL Pegasi A (IRAS 23166+1655 A) and LL Pegasi B (IRAS 23166+1655 B) have a orbital period of c. 800 years.