Categories: Science & Environment

Astronomers spot young rogue planet engulfing its surroundings

WASHINGTON, Oct 9 (Reuters) – Just as Earth orbits the sun, most planets discovered beyond our solar system orbit a host star. But some exist on their own, called rogue planets. Although their origins are poorly understood, astronomers have spotted a voracious one in its infancy that offers new insight into these lonely worlds.

Researchers said this rogue planet, named Cha 1107-7626, is about five to 10 times more massive than Jupiter, the largest planet in our solar system. It was observed during a strong growth spurt at the center of a disk of gas and dust, forming much like a young star, as it engulfed surrounding matter at a speed never before seen in such an object.

At its peak in August this year, it was consuming the material at a rate of six billion tonnes per second, about eight times faster than just a few months earlier.

“The explosion we detected is extraordinary because it resembles some of the most intense growth phases observed in young stars. It reveals that the same physical processes that drive star formation can also occur on a planetary scale,” said astronomer Víctor Almendros-Abad of the INAF Astronomical Observatory in Palermo, Italy, lead author of the study published this month in Astrophysical Journal Letters.open a new tab.

“This object is about one to two million years old. It is very young by astronomical standards,” Almendros-Abad said.

Almendros-Abad said the rogue planet appears to be in its final stages of formation and is not expected to gain much more mass. Researchers believe it has powerful magnetic fields channeling matter from the swirling disk inward, a phenomenon so far observed only in stars.

The researchers observed Cha 1107-7626 using the European Southern Observatory’s Very Large Telescope, based in Chile. It is located in our galaxy, the Milky Way, approximately 620 light years from Earth, in the constellation Chameleon. A light year is the distance light travels in a year, or 5.9 trillion miles (9.5 trillion km).

Rogue planets, also known as free-floating planetary-mass objects, typically have a mass several times that of Jupiter, existing as isolated systems free-floating in space and not gravitationally bound to a host star.

“How these objects form remains an open question,” said Belinda Damian, co-author of the study and an astronomer at the University of St Andrews in Scotland.

In theory, Damian said, they can form like stars do through the collapse of an interstellar cloud of gas and dust, known as a molecular cloud, or they can form like an ordinary planet in a disk of material rotating around a newborn star, only to be ejected somehow from that planetary system.

Although Cha 1107-7626 – a gas giant like the largest planets in our solar system, rather than a rocky world like Earth – forms in the same way as a star, it will not achieve the mass needed to trigger hydrogen fusion at its core like a star.

Other celestial objects called brown dwarfs also form in this way and fail to become a star. Brown dwarfs have a mass about 13 to 81 times that of Jupiter and can burn deuterium – a form of hydrogen – in their core for a limited time.

Cha 1107-7626 could provide a better understanding of how certain rogue planets are born.

“This is a really exciting discovery because we generally tend to think of planets as calm, stable celestial bodies, but we now see that these objects can be dynamic, just like stars in their nascent stage,” Damian said. “This somehow blurs the line between stars and planets and gives us insight into the earliest periods of rogue planet formation.”

Reporting by Will Dunham, editing by Rosalba O’Brien

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