"Alien megastructure" star may be a sign of a dying world

In 2015, reports of an unusual signal observed around a distant star spurred suggestions of the presence of an alien megastructure. But new research suggests that the bizarre discovery could instead be the sign of a destroyed world.

While most planets orbit their stars from a safe distance, some see their suns up close and personal. Orbiting far closer than Mercury, these worlds experience extreme temperatures that cause their atmospheres to expand. If the planet is too small, with too little gravity to hold on to the growing atmosphere, it can wind up losing it. A handful of worlds have been spotted with the remnants of their atmospheres trailing along behind them.

“Disintegrating planets can reveal extremely important compositional information, which is the primary reason we are interested in them,” Jake Hanson, a doctoral student at Arizona State University, told Astronomy by email. Hanson, who is studying how exoplanets lose their atmospheres, presented his research in April at the Astrobiology Science Conference in Mesa, Arizona.