Rogue planet found floating in our sunless galaxy

Jan Skowron / Astronomical Observatory / University of Warsaw

Researchers have discovered a “floating” planet traveling through our galaxy, detached from any sun.

Scientists discovered the planet through a technique called a gravitational microlens, which is only possible when a telescope is in near perfect alignment with the observed object and the source star. When the objects are aligned, the foreground object amplifies the light from the background star.

The microlens were first used to find black holes, but scientists were able to identify the floating planet because of the way it bent light from more distant stars.

In the study published today in Letters from astrophysical journals, astronomers have declared the planet the smallest rogue world ever to be discovered. It is believed to have mass somewhere between Earth and Mars and emitted a measurable signal for only 42 minutes.

Przemek Mroz, postdoctoral researcher at the California Institute of Technology and lead author of the study, commented:

The chances of observing the microlens are extremely slim because three objects – the source, the objective and the observer – must be almost perfectly aligned.

It is the shortest microlens event ever found, hence the lowest mass planet ever found by microlens. It’s really exciting because it’s a very small piece of rock.

The Optical Gravitational Lens (OGLE) experiment in Poland observed a number of planets roaming free, but because the chances of spotting one are so rare, Mróz said they could in fact be as common as the stars throughout our galaxy.

The data containing information about the floating planet was obtained in 2016, but Mróz and his colleagues did not spot it until they decided to look at the archival data during the COVID-19 pandemic.

When we first spotted this event, it was clear that it must have been caused by an extremely small object.

We can rule out that the planet has a star in about eight astronomical units.

StarsAP Images

For reference, Saturn is 9.5 astronomical units from our sun. It is possible that the new planet is attached to a star, but it would take years of additional observation to determine if this is the case – long enough for a potential parent star to shift position so that its light can be separated. from that of the background. Star.

Floating planets are believed to appear when clouds of gas collapse inward or when they are ejected from a star’s orbit. Studying unattached planets could help astronomers learn more about the history of planetary systems like the solar system.

NASA’s Nancy Grace Roman Space Telescope, due to launch in the mid-2020s, is expected to help identify floating planets.

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