At least five Neptune-like planets have been spotted orbiting the star HD 10180—and there's evidence of two more worlds, one farther from the star and another closer in.
If the latter observations can be confirmed, the innermost planet may hold the record for the lowest-mass extrasolar planet, or exoplanet, seen to date.
"We remain cautious about the existence of the innermost and outermost planets," said study lead author Christophe Lovis, an astronomer with the Observatory of Geneva in Switzerland.
"But I am confident that at least one of them will be definitively confirmed soon, thus making this system the most populous known so far."