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Illustration titled “Evolution of 'Blue Lurker' Star System.” It features six boxes, in two rows of three. The top left shows a large circular path of a star surrounding a small circular path of two rotating stars. The top middle box shows two stars rotating around each other, shown with blue streaks, and a third star is in the distance. The top right box shows a large fiery orange star with a feeding line to another distant star. The bottom left box shows a small yellow star on a black background surrounded by a faint red ring of gas. The bottom middle box shows the yellow star with a white box around it. Lines lead from this small box to the bottom right panel, showing a large fiery yellow star. The words “Artist's Concept” is at the bottom right.

Hubble Artwork of the Evolution of "Blue Lurker" Star System

Evolution of a "Blue Lurker" Star in a Triple System Panel 1: A triple star system containing three Sun-like stars. Two are very tightly orbiting. The third star has a much wider orbit. Panel 2: The close stellar pair spiral together and merge to form one more massive star. Panel 3: The merged star evolves into a giant star. As the huge photosphere expands, some of the material falls onto the outer companion, causing the companion to grow larger and its rotation rate to increase. Panels 4-5: The central merged star eventually burns out and forms a massive white dwarf, and the outer companion spirals in towards the white dwarf, leaving a binary star system with a tighter orbit. Panel 6: The surviving outer companion is much like our Sun but nicknamed a "blue lurker." Although it is slightly brighter bluer than expected because of the earlier mass-transfer from the central star and is now rotating very rapidly, these features are subtle. The star could easily be mistaken for a normal Sun-like star despite its exotic evolutionary history.

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