"A stellar binary believed to contain the planet with the biggest known diameter and the least dense. This would have been only the second planet with such a low density. Later measurements showed it wasn't that inflated, and has the expected radius for a highly irradiated core-less Hot Jupiter."@en . . . . "A stellar binary believed to contain the planet with the biggest known diameter and the least dense. This would have been only the second planet with such a low density. Later measurements showed it wasn't that inflated, and has the expected radius for a highly irradiated core-less Hot Jupiter."@en . . "HAT-P-1 System"@en . . .