Young Rogue Planet Shows Star-Like Growth Behavior

Astronomers observe Cha 1107-7626, a rogue planet forming like a star, consuming gas at six billion tons per second.

A Planet Without a Star

Most known planets orbit stars, but some exist independently in space—these are called rogue planets. One such object, Cha 1107-7626, has drawn attention for its rapid growth and unusual formation process. Estimated to be five to ten times the mass of Jupiter, it was observed in the midst of a dramatic accretion event. At its peak in August, the planet absorbed surrounding gas and dust at a rate of six billion tons per second.

This behavior resembles the intense growth phases typically seen in young stars. According to Víctor Almendros-Abad, lead author of the study, the same physical mechanisms that drive star formation appear to operate on a planetary scale. The planet is believed to be between one and two million years old, placing it in the early stages of its development. Researchers suggest it is nearing the end of its formation and unlikely to gain much more mass.

Formation Mechanisms and Magnetic Activity

Cha 1107-7626 was studied using the Very Large Telescope in Chile, operated by the European Southern Observatory. Located about 620 light-years from Earth in the constellation Chamaeleon, it resides within our Milky Way galaxy. The planet appears to be surrounded by a disk of gas and dust, with strong magnetic fields channeling material inward—an effect previously observed only in stars. This discovery challenges existing assumptions about how planetary-mass objects evolve.

Rogue planets, also known as free-floating planetary-mass objects, typically have masses a few times greater than Jupiter and are not gravitationally bound to any star. Their origins remain uncertain, with two main theories proposed. One suggests they form like stars through the collapse of a molecular cloud, while the other posits they form in planetary systems and are later ejected. Cha 1107-7626 seems to support the former, given its star-like formation characteristics.

Blurring the Line Between Stars and Planets

Unlike stars, Cha 1107-7626 lacks the mass needed to initiate hydrogen fusion at its core. It shares similarities with brown dwarfs, which also form like stars but fall short of becoming fully-fledged stellar objects. Brown dwarfs range from 13 to 81 times the mass of Jupiter and can briefly burn deuterium, a hydrogen isotope. Cha 1107-7626, being less massive, will remain a gas giant without fusion capabilities.

Belinda Damian, co-author of the study, noted that this discovery highlights the dynamic nature of planetary formation. Planets are often viewed as stable and passive, but Cha 1107-7626 demonstrates that they can undergo energetic growth phases. The observation offers a rare glimpse into the early evolution of rogue planets and may help refine models of planetary and substellar formation. It also raises questions about the diversity and complexity of objects that populate interstellar space.