Researchers of a new study found that free-floating planets made from tiny, cold clouds can also be born-free, without a parent star.
Rogue, free-floating planets that are made from tiny, cold clouds are often believed to be planets that have been "thrown out" from existing planetary systems. However, a new observation made by researchers using Chalmers University of Technology telescopes revealed that these planets can also be born free of a parent star and may not always be a part of an existing planetary system.
According to previous studies, there are more than 200 billion free-floating planets in the Milky Way. For the new study, researchers studied the Rosette Nebula, a huge cloud of gas and dust 4600 light years from Earth in the constellation Monoceros (the Unicorn).
"The Rosette Nebula is home to more than a hundred of these tiny clouds - we call them globulettes", Gösta Gahm, astronomer at Stockholm University, who led the project, said in a press release. "They are very small, each with diameter less than 50 times the distance between the Sun and Neptune. Previously we were able to estimate that most of them are of planetary mass, less than 13 times Jupiter's mass. Now we have much more reliable measures of mass and density for a large number of these objects, and we have also precisely measured how fast they are moving relative to their environment."
According to Gahm, in the vast history of the Milky Way, many such nebulae like the Rosette bloomed and then faded away.
Researchers observed that these globulettes were very dense and compact and had very thick cores too. Owing to their density, many of these globulettes collapse under their own weight to form free-falling planets. The larger globulettes go on to form brown dwarfs, commonly known as failing stars.
While making the observation, researchers also found that tiny clouds are moving outwards through the Rosette Nebula at high speed, about 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. They have been accelerated out from the centre of the nebula thanks to pressure from radiation from the hot stars in its centre", explained Minja Mäkelä, astronomer at the University of Helsinki.
