Thursday, Jan. 26, 2023|
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Image courtesy CFHT
An artist's depiction of a rogue planet drifting through space.
Astronomers using Maunakea observatories have discovered at least 70 planets within our galaxy that do not orbit a star.
A team of astronomers from the Laboratoire d’Astrophysique de Bordeaux in France and the University of Vienna, in Austria, used data collected from several telescopes around the world, including two on Maunakea, to locate the rogue planets throughout the Milky Way.
Rogue planets do not orbit stars or any other gravity source, which can make them extremely difficult to detect compared to normal planets.
Whereas a normal planet can be detected by analyzing variations in the movements of its brighter host star, the lack of any host obviously makes this impossible for rogue planets.
Previously, rogue planets were detectable through chance alignments when a planet happened to block the light from a more distant star, but such occurrences are so rare that follow-up observations are impossible.
However, astronomer Nuria Miret-Roig, surmising that younger rogue planets are still glowing from the heat of their formation, led a team that analyzed more than 20 years of data from the Canada-France-Hawaii Telescope, the Subaru Telescope and others across a wide range of wavelengths to identify several objects moving across the sky without being bound to a star or gravitational host.
“We measured the tiny motions, the colours and luminosities of tens of millions of sources in a large area of the sky,” Miret-Roig said in a statement. “These measurements allowed us to securely identify the faintest objects in this region, the rogue planets.”
The objects appear to be planets of masses comparable to Jupiter, located in a region of space just a few hundred light years away.
By studying these wandering planets, astronomers may be able learn how they can exist at all.
While normal planets, such as our own, form from the accretion of material left over from the formation of its host star, it is yet unknown whether rogue planets are formed from clouds of material too small to form a star, or have been ejected from their parent star system, or are formed through other processes.
“There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star,” said fellow project leader Hervé Bouy. “These objects are extremely faint, and finding them is incredibly challenging with current telescopes.”
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