Astronomers discover the largest group of wandering planets ever detected

Scientists have detected 70 wandering planets , the largest group discovered to date without orbiting a star.

A team of astronomers from the European Southern Observatory (ESO) has discovered at least 70 new wandering planets in our galaxy, the largest group of these celestial bodies detected to date.

The planets wandering are elusive cosmic objects with masses comparable to those of the planets in our solar system, but not orbiting a star, but roam freely.

“We did not know how many we could find and we are excited to have detected so many,” says Núria Miret-Roig, an astronomer at the Bordeaux Astrophysics Laboratory (France) and the University of Vienna and the first author of the new study published this Wednesday in the journal Nature Astronomy .

It would normally be impossible to image wandering planets as they move away from any stars that might illuminate them.

However, Miret-Roig and his team took advantage of the fact that, in the few million years after their formation, these planets are still hot enough to shine, making them directly detectable by sensitive cameras installed in large telescopes.

They found at least 70 new wandering planets with masses comparable to Jupiter in a star-forming region near our Sun located between the constellations Scorpio and Ophiuchus.

To detect so many wandering planets , the team used data from various ground- and space-based telescopes spanning some twenty years of observations.

“We measure the small movements, colors and luminosities of tens of millions of sources in a large area of ​​the sky,” explains Miret-Roig.

“These measurements allowed us to reliably identify the fainter objects in this region, the wandering planets,” he adds.

Thousands of overlapping images

The team used observations from ESO’s telescopes: VLT (Very Large Telescope), VISTA (Visible and Infrared Survey Telescope for Astronomy), VST (VLT Survey Telescope) and the MPG / ESO 2.2-meter Telescope, all located in Chile. , along with observations from other facilities.

“We used tens of thousands of wide-field images obtained with ESO’s facilities, corresponding to hundreds of hours of observations and literally tens of terabytes of data,” explains Hervé Bouy, an astronomer at the Bordeaux Astrophysics Laboratory and project leader for this research.

The team also used data from the European Space Agency’s Gaia satellite, which is a great success in the collaboration between ground-based and space telescopes for the exploration and understanding of our Universe.

The study suggests that there could be many more of these elusive starless planets yet to be discovered.

“There could be several billion of these giant, free-floating planets roaming the Milky Way without a host star,” notes Bouy.

By studying these newly discovered wandering planets , the astronomical community can find clues to how these mysterious objects form.

Within the scientific community, there are those who believe that wandering planets can form from the collapse of a gas cloud too small to trigger the formation of a star or that they could have been ejected from their host system, but it is not yet known which. of these mechanisms it is the most likely.