Some Planets May be Born Free, Study Shows

Not all wandering planets are lost, according to a new study published in the journal Astronomy and Astrophysics, which suggests that some of the galaxy's estimated 200 billion free-floating planets formed on their own rather than becoming orphaned somewhere down the line.

The observation is based on a close examination of the Rosette Nebula located 4,600 light-years from Earth in the constellation Monoceros.

Led by Gösta Gahm, an astronomer from Stockholm University, the study focused on tiny clouds called globulettes, of which the Rosette Nebula is home hundreds. Each with a diameter less than 50 times the distance between the Sun and Neptune, these cold, tiny clouds contain all the right characteristics to form planets without a parent star, the researchers observed.

"We found that the globulettes are very dense and compact, and many of them have very dense cores," Carina Persson, an astronomer at Chalmers University of Technology said. "That tells us that many of them will collapse under their own weight and form free-floating planets. The most massive of them can form so-called brown dwarfs."

Based on their observations, the researchers found that these globulettes are moving outward through the nebula at speeds of 80,000 kilometers per hour.

"We think that these small, round clouds have broken off from tall, dusty pillars of gas which were sculpted by the intense radiation from young stars," Minja Mäkelä, astronomer at the University of Helsinki, explained. "They have been accelerated out from the center of the nebula thanks to pressure from radiation from the hot stars in its center."

According to Gahm, these tiny clouds are being thrown out of the nebula and, given the countless nebulae that have come and gone during the history of the Milky Way, the researcher explains there is no telling how many globulettes have formed as a result.

"If these tiny, round clouds form planets and brown dwarfs, they must be shot out like bullets into the depths of the Milky Way," he said. "There are so many of them that they could be a significant source of the free-floating planets that have been discovered in recent years."