Appearing as a ghostly apparition in deep space, the LL Pegasi spiral nebula signals the death of a star — and the world’s most powerful radio observatory has delved into its deeper meaning.
Left: HST image of LL Pegasi publicized in 2010. Credit: ESA/NASA & R. Sahai. Right: ALMA image of LL Pegasi. Credit: ALMA (ESO/NAOJ/NRAO) / Hyosun Kim et al.
When the Hubble Space Telescope revealed the stunning LL Pegasi spiral for the first time, its ghostly appearance captivated the world.
Known to be an ancient, massive star, LL Pegasi is dying and shedding huge quantities of gas and dust into space. But this is no ordinary dying star, this is a binary system that is going out in style.
The concentric rings in the star system’s nebula are spiraling outwards, like the streams of water being ejected from a lawn sprinkler’s head. On initial inspection of the Hubble observation, it was assumed that the spiral must be caused by the near-circular orbit of two stars, one of which is generating the flood of gas. Judging by the symmetry of the rings, this system must be pointing roughly face-on, from our perspective.
Though these assumptions generally hold true, new ...