No less than seventy lonely planets discovered

A great success, because never before have so many such mysterious galactic nomads been tracked down simultaneously.

By solitary planets we mean solitary, wandering specimens that do not orbit a parent star; they roam free. Until now, however, few such strange planets were known. But a team of astronomers has changed that. Using various telescopes, they have discovered no fewer than 70 new, lonely planets in our Milky Way Galaxy. “We didn’t know how many to expect, but we’re glad we found so many,” said study leader Núria Miret-Roig.

The researchers found the 70 lone planets in a nearby star-forming region in the constellations Scorpio and Serpent Bearer. The planets all have a mass comparable to that of planet Jupiter in our own solar system.

Good luck

The fact that 70 new orphan planets have now been identified is a great success; never before have so many such mysterious galactic nomads been tracked down simultaneously. And that is not so strange. Lonely planets are hard to find cosmic objects. Because they do not have a star in their vicinity, their presence is difficult to determine.

How?

But the astronomers have come up with something for that. Miret-Roig and her team took advantage of the fact that lonely planets ‘afterglow’ for the first few million years after their birth. This makes them directly observable with the sensitive (infrared) cameras of large telescopes.

This image shows the locations of 115 potential solitary planets (circled in red) recently discovered in a star-forming region in the constellations Scorpio and Serpent Bearer. Image: ESO/N. Risinger (skysurvey.org)

In finding the solitary planets, the team used data collected over a period of about 20 years with a number of telescopes on the ground and in space. “We measured the small movements, colors and luminosity of tens of millions of sources across a large region of the sky,” explains Miret-Roig. “These measurements allowed us to identify with certainty the faintest objects in this region, the solitary planets.”

The researchers used, among other things, observations from ESOs Very Large Telescope, Visible and Infrared Survey Telescope for Astronomy (VISTA) and VLT Survey Telescope (VST). “We have used tens of thousands of images from ESO facilities, which correspond to hundreds of hours of observations and literally tens of terabytes of data,” said researcher Hervé Bouy.

Origin

With the discovery of 70 new orphan planets, astronomers have taken another important step in understanding the origins and properties of these mysterious galactic nomads. Because by scrutinizing them closely, astronomers may be able to find clues as to how these mysterious objects come to life; something that is still shrouded in mystery. Some scientists suspect that solitary planets are formed by the contraction of a gas cloud too small to form a star. Another possibility is that they were ejected from planetary systems. But which mechanism is more likely remains unclear.

Research into nomadic planets continues. And there may be many more of these elusive, starless planets waiting to be discovered. “There could be billions more of these solitary giant planets roaming our Milky Way galaxy,” Bouy said. However, astronomers depend on further technological developments for a detailed analysis of these planets. The Extreme Large Telescope still under construction is expected to make a significant contribution. “The objects are extremely faint,” Bouy says. “With the existing facilities, they can hardly be studied. The ELT will be crucial to gather more information about most of the solitary planets we have tracked.”