IRAS 23166+1655

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IRAS 23166+1655
Reflection nebula
Protoplanetary nebula
Pre-planetary nebula, IRAS 23166+1655.jpg
Hubble Space Telescope image of IRAS 23166+1655, taken in the near-infrared. The bright object to the right is a star much closer to Earth. It was used as a guide star for adaptive optics corrections that allowed the Keck II telescope to resolve the LL Pegasi binary pair.[1]
Observation data: epoch
Right ascension 23h 19m 12s
Declination +17° 11′ 35″
See also: Lists of nebulae

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 the spiral arms and their rate of expansion is consistent with estimates of the pair's c. 800 year orbital period based on their apparent angular separation. Its position is RA 23 19 12, Dec +17 11 35.[3]


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