Scientists believe such objects—also called homeless, free-floating, or rogue planets—can form in one of two ways. Either they're ejected from star systems, or they form independently.

About a dozen such untethered orbs were identified more than a decade ago in the Orion Nebula. Since then the pool of candidates has grown to several dozen. (See "'Nomad' Planets More Common Than Thought, May Orbit Black Holes.")

The latest discovery is the first to be found outside a star-forming region, said Étienne Artigau, an astronomer at the Université de Montréal and a co-author of the study, published Wednesday by the journal Astronomy & Astrophysics.

Compared with other potential homeless planets, the new candidate is also older, colder, and much closer to Earth—approximately